The mechanism of physical elimination of indigenous bacteria was ultrastructurally and immunohistochemically investigated in microvillous columnar epithelial cells of Peyer's patches and intestinal villi of the rat jejunoileum. From ultrastructural observation, the microfilaments accumulated to form several electron-dense layers beneath the bacteria adhering to the cell membrane, which was slightly invaginated in the epithelial cells of Peyer's patches and intestinal villi. As the microfilamentous layers were forming, the end portions of invaginations were deformed into a cone-shape and were finally collapsed. At the same time, the end portions of the adhered bacteria were also deformed into cone-shapes. The bacterial cells were moved back toward the invagination orifices with no morphological change in their inner structure. From immunohistochemical observation, β-actin and nonmuscle-type myosin were detected at the thin layer just beneath the invaginated cell membrane. These findings suggest that indigenous bacteria which adhere to epithelial cells are removed by only a physical action of actin and myosin filaments, but are not killed. This bacterial cell removal system might lead to the establishment of a settlement of indigenous bacteria on host cells.
Melatonin prevents neuronal cell death in ischemic brain injury. This study investigated whether melatonin inhibits the apoptotic signal through the activation of Raf-MEK-ERK and its downstream targets, including 90 ribosomal S6 kinase (p90RSK) and Bad. Adult male rats were treated with melatonin (5 mg/kg) or vehicle prior to middle cerebral artery occlusion (MCAO). Brains were collected 24 hr after MCAO. We confirmed that melatonin significantly decreases the number of TUNEL positive cells in the cerebral cortex. Western blot analysis showed that levels of Raf-1, MEK1/2, and ERK1/2 phosphorylation decrease in vehicle-treated animals. Melatonin prevents the injury-induced decrease of Raf-1, MEK1/2, and ERK1/2 phosphorylation. Also, it inhibits the injury-induced decrease of p90RSK and Bad phosphorylation. Recently, we reported that melatonin prevents the injury-induced reduction of interaction between pBad and 14-3-3 and inhibits the activation of caspase-3. Subsequently, melatonin prevents the injury-induced an increase of cleaved PARP levels. Taken together, these results suggest that melatonin prevents cell death resulting from ischemic brain injury, and that its neuroprotective effects are mediated by the activation of Raf/MEK/ERK/p90RSK cascade.
A total of 101 Actinobacillus pleuropneumoniae isolates from diseased pigs taken from across Japan during 2002 to 2005 were examined for antimicrobial susceptibility. All isolates were susceptible to ceftiofur, erythromycin, florfenicol and enrofloxacin. Antimicrobial-resistant isolates to oxytetracycline (OTC) (27.7%), dihydrostreptomycin (10.9%), thiamphenicol (10.9%), kanamycin (5.9%), trimethoprim (4.0%) and ampicillin (2.0%) were recognized. OTC-resistant isolates taken from 1986 to 2005 were examined for the tetracycline resistance gene. In OTC-resistant isolates, tetB has been the most frequently isolated gene in Japan. It is likely that the dissemination of tetB has contributed to the increased OTC resistance of A. pleuropneumoniae in Japan.
Serum amyloid A (SAA) is one of the major acute phase proteins in cats that has potential to be used as an inflammatory marker. A previous study showed that the human SAA turbidimetric immunoassay (hSAA-TIA) could be used to measure the SAA concentration in cats. The objectives of the present study were to assess use of hSAA-TIA for determining the feline SAA concentration and to evaluate its clinical application. Recombinant feline SAA protein (rfSAA) was expressed in Escherichia coli and purified for SDS-PAGE and immunoblot analysis with anti-human SAA antibodies. The concentration of rfSAA was determined by ELISA and hSAA-TIA. Plasma SAA concentrations were measured in healthy and diseased cats by hSAA-TIA. The time-courses changes in the SAA and α1-acid glycoprotein (AGP) concentrations in the cats after ovariohysterectomy were investigated. In SDS-PAGE, rfSAA was detected as a clear band that reacted with anti-human SAA antibodies. There was significant correlation between the SAA concentration measured by ELISA and hSAA-TIA. The SAA concentration of the diseased cats (n=263) was significantly increased (P<0.01; 0.0-88.9 mg/l, mean: 7.52 mg/l) compared with that in the healthy cats (n=26; 0.0-0.9 mg/l, mean: 0.14 mg/l). No correlation was observed between SAA and WBC in the diseased cats. The SAA concentration changed more rapidly and remarkably than the AGP concentration after ovariohysterectomy. The present study revealed that hSAA-TIA is useful for determination of the feline SAA concentration. Measurement of the SAA concentration, in addition to the WBC count, would be clinically valuable as a routine test to detect inflammation.
A six-year-old female Labrador retriever dog was suffering from osteomyelitis in her hindlimb. A puncture wound caused by a rotted bamboo stick was presumed as the source of infection. The dog suffered from pre-existing aortic stenosis, but otherwise exhibited no significant abnormality in her systemic conditions excluding claudication of the left hindlimb. The results of cytology and pathological examinations of biopsy samples revealed the diagnosis of mycotic osteomyelitis in this dog. Mycological and DNA tests showed the pathogen as the mushroom Schizophyllum commune. Antibiotic sensitivity testing also revealed susceptibility to itraconazole, which was used to successfully treat the dog. This is a rare case of canine basidiomycosis with S. commune as the etiologic agent.
Since outbreaks of highly pathogenic avian influenza (HPAI) in both human and poultry from 2003, it is critical to have effective vaccines. A cDNA fragment coding the entire hemagglutinin (HA) gene derived from an H5N1 strain (A/duck/China/E319-2/03) was cloned and expressed using the baculovirus system. Two weeks after receiving two doses of recombinant HA (rHA) vaccines, chickens develop high antibody response for hemagglutination inhibition (HI) at titer 7.2 log2. Challenge studies revealed that vaccinated chickens with HI titers greater than 3 log2 could have immunoprotection against the same HPAI H5N1 strain virus challenge through intranasal route. Additionally, HI titer of 5 log2 determined whether the live viruses could not be detected from oropharyngeal, cloacal discharge or in tissues. This result suggests that the rHA expressed from baculovirus system could be a candidate for the development of a safe and efficient subunit vaccine for HPAI (H5N1).
Humic substances are formed during the decomposition of organic matter in humus, and are found in many natural environments in which organic materials and microorganisms are present. Oral administration of humus extract to mice successfully induced effective protection against experimental challenge by the two subspecies, Trypanosoma brucei brucei and T. bruceigambiense. Mortality was most reduced among mice who received a 3% humus extract for 21 days in drinking water ad libitum. Spleen cells from humus-administered mice exhibited significant non-specific cytotoxic activity against L1210 mouse leukemia target cells. Also, spleen cells produced significantly higher amounts of Interferon-γ when stimulated in vitro with Concanavalin A than cells from normal controls. These results clearly show that administration to mice of humus extract induced effective resistance against Trypanosoma infection. Enhancement of the innate immune system may be involved in host defense against trypanosomiasis.
Optimal condition for the cryopreservation of canine CD34+ cells was explored. Canine bone marrow CD34+ cells were isolated from 5 healthy dogs by a magnetic- activated cell-sorting system using a monoclonal antibody specific to canine CD34. These cells were cryopreserved by 4 different methods: 2 different cryoprotectant solutions-solutions A (fetal bovine serum containing 10% dimethylsulfoxide (DMSO) and B (physiological saline containing 5% DMSO, 6% hydroxyethyl starch, and 4% bovine serum albumin)-were used in combination with 2 different freezing procedures-in a rate-controlled programmed freezer (PF) and in an ordinary freezing container. The cell viability, cell recovery rates, and colony-forming unit (CFU) recovery rates were examined following cryopreservation for 1 week, 4 weeks, and 6 months. The values of these parameters were significantly higher for the CD34+ cells that had been frozen in Solution B than for those that had been frozen in Solution A, regardless of the freezing procedure employed. The highest CFU recovery rate following cryopreservation for 6 months corresponded to the cells that had been cryopreserved with Solution B and frozen in a PF. In conclusion, cryopreservation with Solution B in a PF proved to be the most efficient of the 4 cryopreservation procedures investigated in terms of maintaining the quality of canine bone marrow-derived CD34+ cells. This method will be useful for clinical applications involving the use of canine bone marrow-derived CD34+ cells.
The beneficial effects of β-blockers on left ventricular (LV) remodeling have been reported in association with several conditions that cause heart failure, but their effects on the volume overloaded heart failure have not been well defined. Fifty Wistar rats that survived aortocaval (AC) shunt creation were randomly allotted into the following two groups: untreated animals (ACS; n=26) and animals treated with 100 mg/kg/day metoprolol (MP; ACS+MP; n=24). The effects of MP were evaluated at 1, 4 and 12 weeks post-surgery through echocardiographic, hemodynamic and pathologic studies. At 12 weeks post-surgery, LV wall thinning associated with chamber dilatation was observed in ACS but not in ACS+MP. LV end-diastolic pressure and diastolic wall stress were lower in ACS+MP than in ACS. The increase in LV weight was similar in both ACS and ACS+MP at 1 and 4 weeks post-surgery, but at 12 weeks post-surgery, it was significantly greater in ACS+MP than in ACS. At the cellular level, although the cardiac myocyte length progressively increased to a similar extent in both groups, the mean cross-sectional diameter of these cells in ACS+MP was greater than in ACS. In conclusion, MP did not prevent early eccentric hypertrophy in response to volume overload. However, in the late phase of volume overload-induced heart failure, MP appears to allow for myocyte cross-sectional growth and thus prevents LV wall thinning, resulting in a net increase in LV mass. In this manner, MP might contribute to reduction of diastolic wall stress and thereby delay progression of heart failure.
The new ultrasound contrast agent Sonazoid® was injected in 5 healthy dogs, and the time course enhancement in liver parenchyma, portal vein, spleen, and renal cortex was evaluated. In liver parenchyma and spleen, sustained enhancement was observed from at least 8 to 15 min after injection with the peak at 45 sec (liver) and 20 sec (spleen), whereas in the portal vein and renal cortex, the time course enhancement dramatically decreased after the peak enhancement at 30 sec and 20 sec, respectively. No adverse effect was observed after Sonazoid® injection in all the dogs that we examined. Contrast enhanced ultrasound using Sonazoid ® is believed to be useful for observing the parenchyma of canine liver and spleen.
Plasma fibrinogen concentrations were measured in 136 blood samples from 360 days pre-partum to 90 days post-partum for twelve parturitions of seven bottlenose dolphins and in 50 blood samples from the dolphins they were not pregnant as a control. The median concentrations increased gradually, and the values during the fourth stage were higher than those during the other stages. The concentrations during the third stage and the puerperium were almost the same. There were significant differences between the plasma fibrinogen concentrations during the third stage and those of the controls and between those of the fourth stages and the controls (p<0.01). The concentrations peaked during the third stage in four cases and during the fourth stage in three cases.
Because of the lack of an appropriate antibody against the canine CD25 molecule, we investigated whether anti-human CD25 antibody, ACT-1, could be useful in detecting canine T-lymphocyte proliferation. Peripheral mononuclear cells from a dog were cultured for 4 days with or without concanavalin A stimulation. In the last 24 hr, bromodeoxyuridine (BrdU) and human recombinant IL-2 were added. While the cell cycle was detected using anti-BrdU antibody and 7-amino-actinomycine (7-AAD), the cultured cells were stained with anti-canine CD4 antibody and ACT-1. The results showed that T-lymphocytes reactive to ACT-1 were present in the G2/M and G0/G1 phases in 94.4% and 70.0% of CD4-positive T-lymphocytes, respectively, suggesting that flow cytometory with ACT-1 might be useful in detecting canine T-lymphocytes during and after activation.
Several species of birds in Minami Daito Island, an oceanic island located in the far south from the main islands of Japan, were found to be infected with avian Plasmodium. However, no vector species of the avian malaria in this island have been revealed yet. To speculate potential vectors, we collected mosquitoes there and investigated using a PCR procedure whether the mosquitoes harbor avian malaria or not. Totally 1,264 mosquitoes including 9 species were collected during March 2006 to February 2007. The mosquitoes collected were stored every species, sampled date and location for DNA extraction. Fifteen out of 399 DNA samples showed positive for the partial mtDNA cytb gene of avian Plasmodium. Estimated minimum infection rate among collected mosquitoes was 1.2% in this study. Four species of mosquitoes; Aedes albopictus, Culex quinquefasciatus, Lutzia fuscanus and Mansonia sp. had avian Plasmodium gene sequences. Detected DNA sequences from A. albopictus and L. fuscanus were identical to an avian Plasmodium lineage detected in bull-headed shrike (Lanius bucephalus) captured in the island. Different sequences were detected from C. quinquefasciatus, which were corresponding to an avian Plasmodium from a sparrow (Passer montanus) and Plasmodium gallinaceum. Our results suggest that A. albopictus, Lutzia fuscanus, C. quinquefasciatus, and Mansonia sp. could be potential vectors of avian malaria in Minami Daito Island. This study was the first report of molecular detection of avian Plasmodium from mosquitoes in Japan.
In order to investigate the morphological effects of ketoconazole on hypertrophied placentas, we examined the sequential histopathological changes in the placenta from rats exposed to ketoconazole. Ketoconazole was administered orally at 0 and 25 mg/kg/day during gestation days (GDs) 12 to 14, and the placentas were sampled on GDs 15, 17 and 21. All dams showed neither effect on body weight nor any abnormal clinical signs during the experimental period. In the treated group, the placentas appeared more hypertrophic with increases in the weight, diameter and thickness on GD 21. Histopathologically, increased thickness was noted in the labyrinth zone and basal zone on GDs 17 and 21, while on GD 15 the change had been already evident in the former zone. In the labyrinth zone, the mitotic figures of the trophoblasts were significantly elevated on GD 15. A multiple cystic dilatation of maternal sinusoids was observed in some placentas on GDs 15, 17 and 21. In the basal zone, an increase in spongiotrophoblasts and clusters of glycogen cells were detected on GDs 17 and 21. In the decidua basalis, there were no significant changes in either histology or thickness between the control and treated group during GDs 15 to 21. In conclusion, ketoconazole increased the population of composed cells in the labyrinth and basal zone, leading to placental hypertrophy in pregnant rats.
Angiogenesis is essential for tumor progression and is regulated by several angiogenic factors such as vascular endothelial growth factor (VEGF). We investigated the expression and distribution of VEGF and its receptor flt-1 in twelve normal canine tissues in six beagle dogs using immunohistochemistry, RT-PCR and real-time RT-PCR. Immunochemical staining showed that both VEGF and flt-1 were expressed in many tissues and their mRNAs were detected in all organs examined by RT-PCR. Levels of VEGF164 and flt-1 mRNA expression were high in tissues containing many intensely immunopositive cells. The expression levels of VEGF164 and flt-1 mRNA tended to be similar. These results indicated that VEGF and flt-1 are closely associated in canine, as in human tissues, and quantifying their mRNAs might be helpful in evaluating angiogenesis.
Mirodenafil (SK3530) is a new potent and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5). Recent clinical trials have demonstrated that mirodenafil is an effective treatment for erectile dysfunction. Its mechanism of action is enhancement of nitric oxide (NO) induced cGMP formation resulting in significant relaxation of the corpus cavernosum (CC). The aim of this study was to investigate the oral efficacy of mirodenafil in an acute spinal cord-injured rabbit model. Mirodenafil or sildenafil citrate was given orally to male rabbits with a surgical transection of the spinal cord at the L2-L4 lumbar vertebra or ischemic-reperfusion spinal cord injury (SCI). Erections were evaluated in a time-course manner by measuring the length of the uncovered penile mucosa. In the transection SCI model, penile erections were induced at 0.3, 1 and 3 mg/kg of mirodenafil but sildenafil only showed an erectile response at 3 mg/kg. The effects of 1 and 3 mg/kg of mirodenafil were significantly increased by intravenous injection of sodium nitroprusside (SNP), a nitric oxide donor. In the ischemic-reperfusion injury model, 3 mg/kg of either mirodenafil or sildenafil produced a penile erection response. After injection of SNP, the lengths of immediate penile erections were significantly increased in the 1 and 3 mg/kg mirodenafil and 3 mg/kg sildenafil groups. The onset of erectile activity was faster with mirodenafil than with sildenafil citrate. These results demonstrate that mirodenafil may be useful for treating erectile dysfunction in patients with a spinal cord injury.
The Spontaneously Diabetic Torii (SDT) rat has recently been established as a new model of non-obese type 2 diabetes. In this study, we examined changes in hepatic glucose metabolism in prediabetic and diabetic SDT rats compared with age-matched control rats. The prediabetic state was confirmed at 16 weeks of age, and the diabetic state was confirmed at 24 and 32 weeks of age. Decreases in glucokinase mRNA levels and activity were observed in the prediabetic state. In this state, glycogen synthase activity and glycogen content were also decreased in the SDT rat. In addition to the above changes, glycogen phosphorylase mRNA and activity were decreased and gluconeogenetic enzyme mRNA levels were significantly increased in the diabetic state. These results indicate there is a great potential that abnormalities in hepatic glucose metabolism play a role in the progression to onset of diabetes. We suggest that the SDT rat is a valuable diabetic model for investigations into mechanisms or causes of progression to diabetes.
This study examined the uterine oxytocin- (OTR) and estrogen- (ER) receptor mRNA levels during and after pseudopregnancy (PSP) in rats. An increased OTR mRNA level was observed from day 14 of PSP, and the maximal level was attained during the following proestrus. The levels of ERα mRNA were low during PSP and significantly increased during the following estrus. The level of ERβ mRNA was significantly decreased during proestrus and then returned to the values observed during days 7-14 of PSP by estrus. These results suggest i) suppression of ERα mRNA during the luteal phase and that ii) the changes in OTR, ERα and ERβ mRNA levels during proestrus and estrus following PSP are similar to those during the normal estrous cycle.
A total of 230 Salmonella isolates representing 33 serotypes originated from food (pork, beef, chicken meat, duck meat, and shrimp), domestic animals (pig, chicken, and duck), and human (children with diarrhea) in the Mekong Delta, Vietnam were examined for the antimicrobial resistance to 10 antibiotics. Of the 230 Salmonella isolates examined, 49 (21.3%) showed antimicrobial resistance. Thirty-eight isolates (16.5%) were resistant to oxytetracycline, 26 (11.3%) to chloramphenicol, 17 (7.4%) to nalidixic acid, 16 (7.0%) to streptomycin, 5 (2.2%) to kanamycin, and 4 (1.7%) to ampicillin. No isolate showed resistance to gentamicin, cefazolin, ceftriaxone, and ciprofloxacin. Among the resistant isolates, nineteen isolates were resistant to one antimicrobial agent, 10 to two, 15 to three, 3 to four, and 2 to five antimicrobial agents. The resistance rate of Salmonella isolates from the Mekong Delta, Vietnam to these antimicrobial agents seems to be relatively lower than the results of developed countries and even those of the neighboring countries.
Since high levels of prions, the causative agent of bovine spongiform encephalopathy (BSE), accumulate in the brain and spinal cord, contamination of beef carcasses with central nervous system tissue (CNST) may occur at post-slaughter process. In this study, we investigated CNST contamination on the surface of beef carcasses using glial fibrillary acidic protein as a marker after splitting and evaluated the effects of washing procedures on contamination removal. High levels of CNST contamination was detected immediately after splitting, especially in the area close to the spinal column. This suggests that spinal cord fragments are attached to carcasses at the time of splitting even though the spinal cords have been removed by vacuum before splitting. Steam cleaning or manually washing with normal pressure water around the spinal column, performed prior to washing with high-pressure water, was found to be effective for reducing the level of CNST contamination. Furthermore, manually washing with high-pressure water could reduce CNST contamination to almost negligible levels. These results are useful for preparation of appropriate sanitation standard operating procedures to reduce the risk of CNST contamination of carcasses for prevention of exposure to BSE prion via the food chain.
During monitoring of raw milk samples from healthy cows for the presence of antibiotic resistant bacteria, one isolate of Klebsiella pneumoniae strain HUF-100 was found to be resistant to oxyimino-cephalosporins and aztreonam. It was found to carry a chromosomally-encoded extended-spectrum β-lactamase that has not been described previously, namely SHV-60. Thus, it must be expected that this strain will spread further among food-producing animals and thereby constitute a reservoir of this resistant strain and resistance gene that can transfer to and cause treatment problems for humans. The present study confirms the hypothesis that some of novel multiple antibiotic resistant zoonotic bacterial pathogens may initially emerge from food animals and reports, for the first time, this type of emergence in Japan.
Orthopedic fixation of irreversibly damaged joints entails the use of artificial joints. Porous coated prostheses require no bone cement, but coating to the implant is susceptible to avulsion from the surface. The purpose of this pilot study was to test an improved non-coated grit blast titanium implant having a direct surface roughness of 33.4 μm with a wide contrast of 251.6 μm between the valleys and peaks, i.e., about ten times rougher than conventional grit blast, and designed with bumpy, acutely articulated depressions. Fifty-six implants (28 grit blast, 28 smooth) were tested in the femora of 7 healthy beagles. Four roughened grit-blast implants were implanted in the left femur and four smooth implants (controls) in the right femur. The 33.4-μm grit-blasted roughening dramatically enhanced the histological effectiveness, and the mechanical effectiveness improved as a consequence. Bone-to-implant ongrowth attained high apposition and integrity at weeks 12 (76.38%) and 16 (80.35%). Shear strength increased with time and continued to be acceptable (14.5 MPa) at the end of the study. Bone matrix was particularly abundant and thick at the end of week 16, indicating progressive mineralization and maturation of remodeled bone matrix and compatibility of the roughened implant. In conclusion, the new grit blast device shows promise as a potentially useful prosthetic implant. Grit blast roughening would facilitate use of the bare implant without coatings or cement, would likely minimize the cost of joint fixation, and would allow relatively easy implantation.
A 6-year-old castrated male Maltese weighing 4.8 kg was presented with a non-healing wound exhibiting purulent discharge after surgery on scar tissue of a chronic twelve-month-old bite wound on the left caudal abdominal region. The dog had previously undergone four surgeries and had been on continuous antibiotic therapy for eight months. Following radiographic and ultrasonographic examinations, the problem was diagnosed as an enterocutaneous fistula of a herniated bowel loop under the skin. Surgical resection of the fistula involving the bowel loop resolved all symptoms.
Bovine oocytes treated using various combinations of 5 μM ionomycin (Ion), 10 μg/ml cycloheximide (CHX) and 5 μg/ml cytochalsin B (CCB) were evaluated to determine developmental rates and ploidy status. The groups were comprised of metaphase II oocytes exposed to Ion for 5 min (Group 1); Ion treatment followed by CHX for 5 hr (Group 2); Ion treatment followed by CHX/CCB for 1 hr and CHX for 4 hr (Group 3); Ion treatment followed by CHX/CCB for 3 hr and CHX for 2 hr (Group 4); and Ion treatment followed by CHX/CCB for 5 hr (Group 5). Group 5 exhibited significantly (P<0.05) lower rates of second polar body (PB) extrusion and higher rates of cleavage and blastocyst development. At 8 hr after Ion treatment, the eggs in groups 2, 3 and 5 were divided into 2 subgroups based on the presence or absence of the second PB and were assessed for cleavage rate and ploidy at the two-cell stage. The cleavage rates did not differ among the activation treatments or between the presence and absence of the second PB in all groups. The diploid rate was significantly (P<0.05) higher in group 5 than in groups 2 and 3. However, the diploid rate in blastocyst-stage parthenotes did not differ among groups 2, 3 and 5. Consequently, oocyte activation by CHX/CCB for 5 hr after Ion treatment could enhance diploid parthenogenetic development in bovine.
To investigate the relationship between the decreased immunity associated with infirmity and low body weight at birth as a consequence of intrauterine growth retardation in Japanese Black calves with stillbirth/perinatal weak calf syndrome, the thymuses and spleens of 13 calves with this syndrome, weighing less than 20 kg at birth, were examined histopathologically. Cytokeratin staining of the thymus was also carried out to examine its composition. The thymus and spleen were classified as grades 0-4 and I-III according to their hypoplasia, respectively. All calves showed a decreased number of thymocytes. One calf was classified as grade 1, which was characterized by a starry sky appearance. Five calves were classified as grade 2, demonstrating a reversion of the cortex-to-medulla ratio, and the rest were classified as grades 3 and 4 showing an indistinguishable boundary between the cortex and medulla. The thymuses of grade 3 and 4 were occupied by stroma cells, and their Hassall bodies and other structures were rarely observed. Six of 13 calves showed a decreased number of splenocytes, grade II or III, and their red and white pulp regions were unclear. The intrauterine growth retardation caused by lack of growth factors during the fetal period might have induced thymic hypoplasia associated with decreased immunity in the calves with stillbirth/perinatal weak calf syndrome. Therefore, intrauterine growth retardation might be associated with one of the causes of decreased immunity involved in infirmity in this syndrome.