Evidence for low androgenicity among Indian (South Asian) men.

There are increasing data indicating profound ethnic differences in the levels of virilization of males. It is well understood that the intensity of testosterone-mediated effects is modulated by sex hormone binding globulin (SHBG) and the CAG repeat lengths in the androgen receptor (AR) gene. We determined the serum testosterone, estradiol and SHBG levels and average CAG repeat lengths among a group of healthy older Indian men living in Connecticut, USA and compared these parameters with those of a reference group of white Caucasian men. We also compared various parameters that represent the end-manifestations of testosterone activity - serum prostate-specific antigen (PSA) levels, lean body mass, skeletal mineralization and visceral fat. Our data suggest that men from the Indian subcontinent are smaller, manifest lower levels of circulating free testosterone, lower mean PSA levels and lean body mass, but are comparable to white Caucasian men in terms of SHBG, estradiol, levels of visceral fat and CAG repeat length. These data suggest that Indian men manifest a lower level of virilization compared to white Caucasian males and that this might be due to lower mean circulating testosterone levels rather than higher AR CAG repeat length or SHBG.

Importance of bone mineral density measurements in evaluating fragility bone fracture risk in Asian Indian men.

UNLABELLED: We evaluated the effect of BMD on fracture risk prediction using FRAX® among Asian Indian men when used in conjunction with clinical risk factors. A majority of our subjects were either osteopenic or osteoporotic, and their fracture risk increased when FRAX® was used in conjunction with femur neck T-scores. INTRODUCTION: Asian Indian men living in the United States may represent a population that is at high and underappreciated risk for fragility bone fractures. PURPOSE: To evaluate the effect of BMD on fracture risk prediction using FRAX® among Asian Indian men when used in conjunction with clinical risk factors. METHODS: Forty four Asian Indian men (mean age 64.9 (±8.4) years) who had lived in the United States for an average of 33.6 (±10.6) years underwent BMD measurement at the proximal femur. Subjects were subjected to a general physical exam and history of fracture, hip fracture in a parent, current smoking and alcohol use, and diagnosis of inflammatory arthritis was obtained. Data from each subject were entered into the FRAX® algorithm and 10-year fracture probabilities were calculated using clinical risk factors (CRFs) alone and in combination with femur neck T-scores. RESULTS: Thirteen subjects (29.5%) had femur neck T-scores ≥ -1.0, 28 (63.6%) T-scores between -1.0 and -2.5, and three (6.8%) T-scores < -2.5. The 10-year probability of a major osteoporotic fracture based on a combination of clinical risk factors and femur neck T-scores was significantly higher than the fracture probability based on clinical risk factors alone (t(43) = 2.58, p = 0.01). CONCLUSIONS: Among Asian Indian men, the 10-year probability of a major osteoporotic fracture increases when femur neck T-scores are added to clinical risk factors in the FRAX® algorithm, and this population have a high fracture probability even in the absence of clinical risk factors.

Granuloma formation around filarial larvae triggered by host responses to an excretory/secretory antigen.

In previous studies using a murine model of filarial infection, granuloma formation was found to be a most important host-protective mechanism. We have also shown that in vitro cytoadherence is a surrogate for the formation of antifilarial granulomas in vivo and that it requires "alternatively activated" host cells and a source of antifilarial antibody. We show here that antibodies against L3 excretory/secretory (E/S) products can facilitate in vitro cytoadherence. We generated a set of hybridomas reactive with filarial E/S products and screened them for their ability to mediate in vitro cytoadherence. One clone (no. 1E9) was positive in this assay. We then screened a novel expression library of filarial antigens displayed on the surface of T7 bacteriophage for reactivity with 1E9. Phage expressing two filarial antigens (TCTP and BmALT-2) reacted with 1E9. Immunization of mice showed that the cohort immunized with BmALT-2 cleared a challenge infection with infective Brugia pahangi L3 in an accelerated manner, whereas cohorts immunized with TCTP cleared larvae with the same kinetics as in unimmunized mice. These data confirm that BmALT-2 is the antigenic target of granuloma-mediated killing of B. pahangi L3. Our findings also confirm previous studies that BmALT-2 is a potential vaccine candidate for filarial infection. Our data reinforce the work of others and also provide a possible mechanism by which immune responses to BmALT-2 may provide host protection.

Determinants of memory in experimental filarial infections in mice.

In this communication, we examine the determinants and duration of memory responses against filarial parasites using an intraperitoneal mouse model of Brugia pahangi infection. We assessed the role of T cells in the memory response against B. pahangi larvae by transferring splenic T cells from wild-type mice primed with L3 into T-cell-deficient mice. We found that mice reconstituted with primed T cells cleared intraperitoneal infections with infective larvae in an accelerated manner. To determine the components that may be responsible for the memory response, we transferred unfractionated T cells or purified CD4+ T cells or CD8+ T cells from BALB/cByJ mice primed a month earlier with L3 into T-cell-deficient BALB/c TCRbeta-/- mice. Recipients were challenged 10 days after adoptive transfer. Our data demonstrated that while either CD4+ or CD8+ T cells are able to confer some level of protection, both are required for an optimal recall response. To evaluate the longevity of the memory response, we primed several groups of wild-type mice at different times over a year. These mice were then challenged with a single injection of B. pahangi L3. The gap between the priming and second injections of larvae ranged between 4 and 60 weeks. We found that the memory responses in BALB/cByJ mice lasted over a year whereas those in C57BL/6 mice waned more rapidly.

Neonatal tolerance and patent filarial infection.

Lymphatic filariasis occurs in endemic pockets. Patent infections with long-term, high-grade microfilaremia do not develop in nonendemic individuals. It is tempting to speculate that individuals with intact immune responses to filarial antigens are capable of dealing with filarial exposure without developing persistent infection. There are published data that support the idea that only those individuals who are impaired in their immune defense against these parasites owing to neonatal tolerization become productively infected with the filarial parasites. If the model is correct, there are profound implications for global eradication.

Acute but not chronic macrophage recruitment in filarial infections in mice is dependent on C-C chemokine ligand 2.

Macrophages play an important role in the formation of granulomas and the clearance of Brugia pahangi infections in mice. However, the factors responsible for the recruitment of these cells to the site of infection are not known. In this study we examined the role of the C-C chemokine ligand 2 (CCL2; also known as macrophage chemotactic factor - MCP1) in macrophage recruitment in intraperitoneal infections with B. pahangi. We observed that CCL2 was expressed by peritoneal exudate cells and was present in the sera of wild-type mice. Serum levels of CCL2 peaked twice during the immune response, once during the early, acute phase and again during the late, chronic phase. To further elucidate the role of this chemokine in the anti-filarial immune response, we compared CCL2 deficient (CCL2(-/-)) mice to wild-type mice. We observed that macrophage recruitment was impaired only during the acute phase in the former. While macrophage recruitment was unaffected during the chronic phase, increased accumulation of B and T lymphocytes was seen in these mice. We further report that larval clearance and the in vitro adhesion of PECs to larvae were unimpaired in these mice.

Inflammatory bowel disease: maladaptation of the vigilant genotype in a hyper-clean world?

Children born of Asian Indian parents who are raised in environmentally hygienic Western societies appear to be highly prone to two diseases, ulcerative colitis and Crohn's disease, collectively known as inflammatory bowel disease or IBD. These ethnically Indian children are similar to an inbred mouse strain, NOD/Lt. Mice of this strain remain diabetes-free when raised in standard mouse colonies, but develop an autoimmune diabetes at high rates when kept in pathogen-free environments. I propose that certain human habitats have, over eons, selected for "vigilant genotypes," wherein combinations of alleles at critical loci result in aggressive immune responses to pathogens. This genetic configuration is adaptive in the selective environment but maladaptive in more hygienic environments, resulting in dysregulated immune effectors. One manifestation of such dysregulation is organ-specific autoimmunity, such as IBD.

Natural course of lymphatic filariasis: insights from epidemiology, experimental human infections, and clinical observations.

Lymphatic filariasis has been described as a "spectral disease". Analysis of the natural course of infection in nonendemic individuals as well as experimental infections of "volunteers" suggests that the filarial parasites are not inherently aggressive infectious agents. Experimental infections of humans with infective larvae result in transient, low-level microfilaremia, if at all. Nonendemic individuals with limited exposure show no evidence of persistent infection or pathology. Nonendemic individuals exposed to repeated infections show accelerated pathology. It is tempting to speculate that normal, immunocompetent residents in an endemic area show either (a) no pathology (endemic normals) because they are subject to the relatively low levels of infection or (b) chronic pathology if they are repeatedly infected. It would appear that only those individuals rendered immunologically tolerant to filarial parasites become productively infected with the filarial parasites. The intensity of transmission may underlie the differences in clinical presentation seen in diverse global pockets of endemicity.

Eosinophils, but not eosinophil peroxidase or major basic protein, are important for host protection in experimental Brugia pahangi infection.

The attenuation of eosinophilia by the administration of monoclonal antibodies to CCR3 consistently correlates with impairment in worm elimination following primary intraperitoneal Brugia pahangi infections in mice. Host protection was unimpaired in mice deficient in eosinophil peroxidase (EPO) or major basic protein 1 (MBP-1), suggesting that eosinophils are essential in host protection but that neither EPO nor MBP-1 alone is.

Murine extramedullary erythropoiesis induced by tick infestation.

Tick saliva contains molecules that modulate the haemostasis, pain/itch responses, wound healing and immune defences of the host. Using BALB/c mice that were each infested with 10 nymphs of Dermacentor andersoni Stiles (Acari: Ixodidae), an attempt has now been made to determine the influence of tick infestation on the expression of leucocyte adhesion molecules in the host. The ticks became fully engorged by the fourth to sixth day of infestation. On the fourth day of infestation, the results of flow cytometry indicated that 2% of the host's splenocytes were expressing high levels of CD49 (alpha4 integrin of VLA-4) and low levels of CD11a (alphaL subunit of the integrin LFA-1). By the eighth day of infestation, 30% of the hosts' splenocytes had this phenotype and were negative for the lineage markers CD3e (T-lymphocytes), DX5 (natural-killer cells of a BALB/c lineage), B220 (B-lymphocytes), CD11b (monocytes/macrophages, granulocytes, natural-killer cells, activated T-lymphocytes, and B-1 cells) and CD11c (myeloid and splenic dendritic cells). Histological examination of the spleens from infested mice revealed disruption of the white-pulp/red-pulp demarcations and the presence of a large number of basophilic normoblasts. The CD11a(lo) population of splenocytes from the tick-infested mice was positive for TER-119 but negative for CD3, B220, CD11b and Gr, confirming that the splenocytes were members of the erythroid lineage. These results indicate that, within 8 days of their initiation, the tick infestations induced extramedullary erythropoiesis in the spleens of their murine hosts.

A double-blinded, placebo-controlled trial of garlic as a mosquito repellant: a preliminary study.

The hypothesis that the ingestion of garlic provides protection against bloodsucking pests such as mosquitoes was investigated using a randomized, double-blinded, placebo-controlled crossover study. Subjects were asked to consume either garlic (one visit) or a placebo (the other visit). They were then exposed to laboratory-reared Aedes aegypti (Linnaeus) (Diptera: Culicidae). The numbers of mosquitoes that did not feed on the subjects, the number of mosquito bites, the weights of the mosquitoes after feeding and the amounts of blood ingested were determined. The data did not provide evidence of significant systemic mosquito repellence. A limitation of the study is that more prolonged ingestion of garlic may be needed to accomplish repellence.

Neonatal outcome in the United Arab Emirates: the effect of changes in resources and practices.

Selective improvements in neonatal care resources and practices were instituted between 1992/1994 (period 1) and 1995/1998 (period 2) following a neonatal audit in the United Arab Emirates. We evaluated the effect of these changes on neonatal mortality rate (NNMR), birth-weight-specific mortality rates and causes of mortality. Overall there was a 17% decline in the NNMR from periods 1 to 2. Mortality rates in infants with birth weight < 1000 g and > 2500 g decreased by 36% and 35% respectively from periods 1 to 2. Modest declines in deaths from asphyxia, sepsis and complications of preterm births occurred from periods 1 to 2 but the differences were not statistically significant.

The L3 to L4 molt of Brugia malayi: real time visualization by video microscopy.

Brugia malayi and other filarial parasites have been studied in great detail, especially in the context of human disease. In common with other nematodes, these organisms molt 4 times in their life cycles, but details of this process have not been described. We have recently developed an in vitro culture system that supports the L3 to L4 molt at high efficiency. This has permitted us to visualize, for the first time, details of this molt using real-time video microscopy. Molting is preceded by a phase of altered motility during which the larva exhibits contractile, coiling movements. The earliest evidence of ecdysis is a clearing at one end, more frequently caudal, caused by the larva retracting from that end. A cleavage develops in the cuticle near the head end, forming a rostral cap, which is continuous with the pharyngeal cuticle. Simultaneously, it retracts out of the cuticle using coiling and writhing movements. This process takes 5 to 10 min. Finally, it retracts out of the cap and extrudes the pharyngeal cuticle. Detachment of the pharyngeal cuticle is the final event in the process and continues up to an hour after the rest of the cuticle has been shed.

Neonatal outcome in the United Arab Emirates: the effect of changes in resources and practices

Selective improvements in neonatal care resources and practices were instituted between 1992/1994 [period 1] and 1995/1998 [period 2] following a neonatal audit in the United Arab Emirates. We evaluated the effect of these changes on neonatal mortality rate [NNMR], birth-weight-specific mortality rates and causes of mortality. Overall there was a 17% decline in the NNMR from periods 1 to 2. Mortality rates in infants with birth weight < 1000 g and > 2500 g decreased by 36% and 35% respectively from periods 1 to 2. Modest declines in deaths from asphyxia, sepsis and complications of preterm births occurred from periods 1 to 2 but the differences were not statistically significant

Exogenous nucleosides are required for the morphogenesis of the human filarial parasite Brugia malayi.

The nematode parasites Wuchereria bancrofti, Brugia malayi, and B. timori cause a human disease known as lymphatic filariasis, which afflicts approximately 120 million people worldwide. The parasites enter the human host from the mosquito as L3 or infective larvae and subsequently differentiate through 2 molts. In this communication, I report that B. malayi and B. pahangi depend on an exogenous source of at least 1 purine and 1 pyrimidine nucleoside to complete the L3 to L4 molt. The requirement for exogenous nucleosides opens the door for possible chemotherapeutic intervention.

Relationship of anti-microbial activity of tetracyclines to their ability to block the L3 to L4 molt of the human filarial parasite Brugia malayi.

The nematode parasites Wuchereria bancrofti, Brugia malayi, and B. timori cause a human disease known as lymphatic filariasis, which afflicts approximately 120 million people worldwide. These organisms are known to contain endosymbiotic bacteria (Wolbachia) that are related to rickettsiae. It has been previously reported that tetracycline blocks the L3 to L4 molt of the filarial parasite B. malayi, and suggested that this was related to their known anti-rickettsial activity. However, this interpretation was tempered by several observations. First, Wolbachia DNA could still be detected in nematodes from tetracycline-treated cultures. In addition, chloramphenicol, which has anti-rickettsial and anti-chlamydial activity, failed to inhibit the molt. These observations could not rule out the possibility that the anti-molting activity of tetracycline is due to pharmacologic activities unrelated to its anti-rickettsial functions. This study shows that chemically modified tetracycline, which does not to have anti-microbial activity, also blocks molting.

Ascorbic acid is a requirement for the morphogenesis of the human filarial parasite Brugia malayi.

The nematode parasites Wuchereria bancrofti, Brugia malayi, and B. timori cause a disease in humans known as lymphatic filariasis, which afflicts approximately 120 million people worldwide. The parasites enter the human host from the mosquito either as L3 or as infective larvae and subsequently differentiate through 2 molts. In this article, we show that B. malayi depends on an exogenous source of vitamin C to complete the L3 to L4 molt, a critical morphogenic step in its life cycle. Brugia malayi apparently belongs to a small group of living organisms that depend on an exogenous source of vitamin C. This group includes only primates (including man) and guinea pigs among mammals.

Kinetics of cellular responses to intraperitoneal Brugia pahangi infections in normal and immunodeficient mice.

Filarial infections evoke exuberant inflammatory responses in the peritoneal cavities of immunocompetent mice. Clearance of infection appears to be dependent on complex interactions between B1 and B2 B lymphocytes, T cells, eosinophils, macrophages, and the products of these cells. In an earlier communication, we described the course of infection in normal immunocompetent mice. In this study, we utilize mice with well-characterized mutations that disable one or more effector components of adaptive immunity in order to determine their roles in host protection. We characterize peritoneal exudate cells by flow cytometry and determine the kinetics of accumulation of each of the different cell types following infection with Brugia pahangi. We find that (i) four-color flow-cytometric analysis of peritoneal exudate cells using anti-CD3, -CD11b, -CD19, and -Gr1 can distinguish up to six different populations of cells; (ii) an initial influx of neutrophils occurs within 24 h of infection, independent of the adaptive immune status of mice, and these cells disappear by day 3; (iii) an early influx of eosinophils is seen at the site of infection in all strains studied, but a larger, second wave occurs only in mice with T cells; (iv) the presence of T cells and eosinophils is important in causing an increase in macrophage size during the course of infection; and (v) most unexpectedly, T-cell recruitment appears to be optimal only if B cells are present, since JHD mice recruit significantly fewer T cells to the site of infection.

The Gell-Coombs classification of hypersensitivity reactions: a re-interpretation.

Gell and Coombs classified hypersensitivity reactions into four 'types'. I suggest that the premise that these reactions represent 'hypersensitivity' manifestations is limiting and that they represent four major strategies that the body uses to combat infectious agents. I further propose that there is a fifth strategy that was not envisioned in the Gell and Coombs classification.

T cells are required for host protection against Brugia malayi but need not produce or respond to interleukin-4.

T cells are known to be required for host protection in mouse models of Brugia malayi infection. Several independent studies in murine models have also highlighted the rapid induction of Th2-like responses after infection with B. malayi or B. pahangi. Previous data from our laboratory have described a significant increase in permissiveness in the absence of interleukin-4 (IL-4), the "prototypical" Th2 cytokine, involved in both the induction and maintenance of Th2 responses. These observations led to our hypothesis that T cells involved in murine host protection would respond to IL-4 signaling and differentiate into cells of the "type 2" phenotype. As such, these cells would presumably also act as major sources of IL-4. To investigate these hypotheses, we performed several adoptive transfers in which we controlled the cell population(s) able to produce or respond to IL-4. We show here that, in contrast to our original hypotheses, IL-4 production and IL-4 receptor expression by T cells are both dispensable for T-cell-mediated host protection. Instead, our data imply that T cells may be required for eosinophil accumulation at the site of infection.