Directional reorientation of migrating neutrophils is limited by suppression of receptor input signaling at the cell rear through myosin II activity

To migrate efficiently to target locations, cells must integrate receptor inputs while maintaining polarity: a distinct front that leads and a rear that follows. Here we investigate what is necessary to overwrite pre-existing front-rear polarity in neutrophil-like HL60 cells migrating inside straight microfluidic channels. Using subcellular optogenetic receptor activation, we show that receptor inputs can reorient weakly polarized cells, but the rear of strongly polarized cells is refractory to new inputs. Transient stimulation reveals a multi-step repolarization process, confirming that cell rear sensitivity to receptor input is the primary determinant of large-scale directional reversal. We demonstrate that the RhoA/ROCK/myosin II pathway limits the ability of receptor inputs to signal to Cdc42 and reorient migrating neutrophils. We discover that by tuning the phosphorylation of myosin regulatory light chain we can modulate the activity and localization of myosin II and thus the amenability of the cell rear to 'listen' to receptor inputs and respond to directional reprogramming.

SUMO fosters assembly and functionality of the MutSγ complex to facilitate meiotic crossing over

Crossing over is essential for chromosome segregation during meiosis. Protein modification by SUMO is implicated in crossover control, but pertinent targets have remained elusive. Here we identify Msh4 as a target of SUMO-mediated crossover regulation. Msh4 and Msh5 constitute the MutSγ complex, which stabilizes joint-molecule (JM) recombination intermediates and facilitates their resolution into crossovers. Msh4 SUMOylation enhances these processes to ensure that each chromosome pair acquires at least one crossover. Msh4 is directly targeted by E2 conjugase Ubc9, initially becoming mono-SUMOylated in response to DNA double-strand breaks, then multi/poly-SUMOylated forms arise as homologs fully engage. Mechanistically, SUMOylation fosters interaction between Msh4 and Msh5. We infer that initial SUMOylation of Msh4 enhances assembly of MutSγ in anticipation of JM formation, while secondary SUMOylation may promote downstream functions. Regulation of Msh4 by SUMO is distinct and independent of its previously described stabilization by phosphorylation, defining MutSγ as a hub for crossover control.

Neonatal testing leading to the identification of Bh (para-Bombay) phenotype in the mother: case report with review of the literature

Para-Bombay is a rare phenotype with a homozygous nonfunctional FUT1 gene and a normal FUT2 gene leading to H-deficient red blood cells (RBCs) with or without ABH substances, depending on inheritance of the ABO gene. This case is about a 5-day-old male baby suffering from sepsis who required a 45-mL packed RBC transfusion. The baby's sample tested as A₁B, D+ and mother's sample tested as group O, D+ with group 4 discrepancy due to ABO isoagglutinins. Further workup of the mother's sample with anti-H lectin was negative, which suggested the mother to be group O_h, D+. Antibody screening was panreactive with negative autocontrol, suggestive of anti-H. The titer of immunoglobulin (Ig)M anti-H was 64, IgG titer using dithiothreitol was 8, and anti-IH was absent. A negative adsorption and elution test suggested that RBCs were devoid of A and B antigens. The father's sample tested clearly as group A₁, D+; hence, the cis-AB blood group was ruled out in the baby. The secretor study of the mother's saliva revealed the presence of B and H substances that neutralized polyclonal B and H antisera. Therefore, we concluded that the mother was of the para-Bombay (B_h) phenotype. This case highlights the importance of reverse grouping and resolving blood grouping discrepancies between mother and child-in this case because of an incongruous ABO blood type of the baby and the mother who was previously tested as group O, D+.

Para-Bombay is a rare phenotype with a homozygous nonfunctional FUT1 gene and a normal FUT2 gene leading to H-deficient red blood cells (RBCs) with or without ABH substances, depending on inheritance of the ABO gene. This case is about a 5-day-old male baby suffering from sepsis who required a 45-mL packed RBC transfusion. The baby’s sample tested as A₁B, D+ and mother’s sample tested as group O, D+ with group 4 discrepancy due to ABO isoagglutinins. Further workup of the mother’s sample with anti-H lectin was negative, which suggested the mother to be group O_h, D+. Antibody screening was panreactive with negative autocontrol, suggestive of anti-H. The titer of immunoglobulin (Ig)M anti-H was 64, IgG titer using dithiothreitol was 8, and anti-IH was absent. A negative adsorption and elution test suggested that RBCs were devoid of A and B antigens. The father’s sample tested clearly as group A₁, D+; hence, the cis-AB blood group was ruled out in the baby. The secretor study of the mother’s saliva revealed the presence of B and H substances that neutralized polyclonal B and H antisera. Therefore, we concluded that the mother was of the para-Bombay (B_h) phenotype. This case highlights the importance of reverse grouping and resolving blood grouping discrepancies between mother and child―in this case because of an incongruous ABO blood type of the baby and the mother who was previously tested as group O, D+.

Hiccups and hyponatremia: Unusual co-presentation in COVID-19

Coronavirus disease (COVID-19) is the newly discovered infectious disease, affecting millions worldwide. Majority of the patients present with mild respiratory syndrome. Some neurological symptoms are reported like anosmia & dysgeusia. We are presenting a case with hiccups as an unusual symptom. An elderly male patient presented to Bapuji teaching hospital attached to JJM medical college, Davangere on 24th July 2020 with intractable hiccups in the last 5 days. There were no other symptoms. Patient's saturation was initially 98% at room air which then dropped to 90%. Based on clinical knowhow, SARS-Cov-2 RNA qualitative RT-PCR test was sent, and the results came positive. Patient improved symptomatically in 2 days and was kept in ward for observation for a total of 7 days. This extremely rare case report brings to light new atypical symptom of COVID-19 are being presented every other day, which shows how the importance being aware of the same.

Prognosis of COVID-19: Red Cell Distribution Width, Platelet Distribution Width, and C-Reactive Protein

Introduction

Cytokine storm is central in the pathobiology of Coronavirus disease 2019 (COVID-19). The pro-inflammatory state and hypoxia disrupt erythropoiesis leading to alterations in red cell distribution width (RDW) and hematocrit. Platelet production increases alongside its destruction, inviting newly formed immature platelets into the circulation. Thus, the platelet distribution width (PDW) and mean platelet volume (MPV) are also affected. The study's objective is to analyze these indices and C-reactive protein (CRP) to elucidate prognostic insights in COVID-19 patients at the time of admission.

Methodology

This study was a retrospective cross-sectional study conducted at Chigateri General Hospital, attached to JJM Medical College, Davangere, over two months, July and August of 2020. Patients falling under categories B and C according to the interim guidelines issued by the Ministry of Health and Family Welfare, Government of India were enrolled in this study. Patients requiring mechanical ventilation and those with a prior diagnosis of malignancy were excepted from the study.

Results

The study population comprised a total of hundred patients. Seventy-five patients survived the disease and were discharged; twenty-five patients succumbed to the viral illness. The mean age of survivors (43.0 +/- 13.6 years) was significantly lesser than that of non-survivors (59.1 +/- 11.5 years) (p <0.001). RDW was significantly different among survivors (p=0.002); PDW and CRP were lower among the deceased (p=0.05 and p=0.10, respectively). Cut off values for RDW as 15%, CRP as 67 mg/l, and PDW as 17% were significantly associated with mortality. Hematocrit and MPV were not significantly associated with mortality. RDW has a sensitivity of 92% and a negative predictive value of 95% in predicting mortality.

Discussion

RDW showed a significant association with increased mortality. Impaired cell-mediated immunity at the onset of infection is responsible for rapid progression to moderate or even severe COVID disease. Since the investigations in our study were ordered at the time of admission, it may lead us to believe that higher RDW is associated with a better patient outcome.

Lower C-reactive protein levels are associated with higher mortality. CRP is a non-specific marker for inflammation. Raised CRP is customarily an indicator of acute inflammation. Notwithstanding, the raised CRP may be an indicator of baseline immune response in early COVID infection.

High PDW shows a significant association with increased mortality. The pathobiology of change in platelet indices in COVID-19 patients is presumably multifactorial: infection of the bone marrow; autoimmune platelet destruction; platelet sequestration. 

Conclusion

Red cell distribution width, platelet distribution width, and C-reactive protein are useful early predictive markers of mortality in COVID-19. Although serial investigations would provide a better picture, these indices at admission can gauge the clinical outcome early in the disease. As there is still a lot to be understood about the natural history of COVID-19, our study aims to propose relatively inexpensive indices of mortality that can aid efficient management.

Neutrophil-to-Lymphocyte, Lymphocyte-to-Monocyte, and Platelet-to-Lymphocyte Ratios: Prognostic Significance in COVID-19

Background and objective

Neutrophils are primarily responsible for activating the immune system, and systemic inflammation destroys CD4+ T lymphocytes and increases suppressor CD8+ T lymphocytes, thereby leading to an increased neutrophil-to-lymphocyte ratio (NLR). An increase in the apoptosis of lymphocytes leads to lymphopenia and elevated thrombopoietin (THPO) promotes megakaryocyte production. The reflections of these inflammatory changes can be vital in gauging the progression of the disease.

This study aimed at examining the prognostic value of normal and derived neutrophil-to-lymphocyte, lymphocyte-to-monocyte, platelet-to-lymphocyte, and mean platelet volume (MPV)-to-platelet count ratios in patients with coronavirus disease 2019 (COVID-19).

Methodology

This was a retrospective cross-sectional study conducted in the wards of Chigateri General Hospital, Davangere for a period of two months. Complete blood count was ordered for all patients at the time of admission along with confirmation of the disease by reverse transcription-polymerase chain reaction (RT-PCR).

Results

The final study population consisted of 100 patients. The mean age of patients who survived (43 years) was significantly lower than the mean age of non-survivors (59.1 years), with a p-value of <0.001. NLR was raised in 60% of the population and was significantly higher in patients who survived the disease, with a p-value of 0.004. The platelet-to-lymphocyte ratio (PLR) also followed a similar trend with a p-value of 0.017. Even though the lymphocyte-to-monocyte ratio (LMR) also mimicked the trend, the statistical association was not significant (p-value: 0.09). The derived NLR and MPV-to-platelets ratios were not found to be significantly associated with mortality in this study.

Discussion

Younger patients had better clinical outcomes in our study population compared to the geriatric age group. A significant correlation between LMR and mortality was observed when a cut-off of 2.5 was considered as a differentiating benchmark.

Conflicting trends were observed in NLR and PLR in our study; however, LMR was in accordance with most other studies. The phase that a patient is in with regard to the natural history of the disease also influences the blood cell ratios. Nonetheless, all three ratios can be used as crucial screening and prognostic tools as they are readily available with the help of a complete hemogram. This is an investigation modality that is widely accessible even in remote areas and resource-limited settings.

Conclusion

These hematological ratios can facilitate in categorizing the disease severity and progression in patients, thereby enabling us to make appropriate and informed clinical decisions. Since the second wave of the novel coronavirus is on the verge of arrival, it is imperative to channel resources for the patients early in their disease course to ultimately prevent complications and reduce mortality.

Hepatitis A: A refreshing perspective through a rare symptom in a teaching hospital in south India

Hepatitis A virus is a common cause of acute viral hepatitis in India, due to lack of clean water and sanitation. Usual presentations include gastroenteritis or a viral respiratory infection. Hepatitis A has a variety of extra-hepatic manifestations which, if failed to be recognized, evades diagnosis. A 28-year-old lady presented with pain abdomen for 1 week, fever with rashes for 1 day. Patient was febrile at the time of examination. Rash was maculopapular with irregular edges, tender. On examining abdomen, tenderness noted in right hypochondrium and epigastrium with hepatomegaly. Patient was then admitted. Working diagnosis was Viral hepatitis for evaluation. Hepatitis A serology was sent which came positive for Ig M. Patient was treated with IV fluids, bile acid sequestrants, IV PPI, IV and oral antibiotics, antihistamines and 3 doses of injection Vit K. Calamine lotion was also given for skin care. Patient improved symptomatically in 2 days and was discharged after 3 days of hospital stay. In our case, the maculopapular rash spreading to the whole body was the major presenting symptom. The presentation of Hepatitis A with rashes maybe seen in around 10% of patients with extrahepatic manifestations along with arthralgia. Differential diagnosis in this case should be erythema multiforme which is the most common maculopapular eruptive rash. Other viral hepatitis causing agents (Hepatitis B&E) have been documented to present with rashes. SLE and Kawasaki disease rarely present with fever with rash with nonspecific multisystemic involvement. Borrelia, Leptospira also have icterus in their presentations. Early diagnosis and management in this case prevented complication such as autoimmune hepatitis, pleural effusion, ascites acute kidney injury. This case presentation urges the need to consider Hepatitis A to be an important differential diagnosis of fever with rash especially in tropical/sub-tropical countries with poor sanitation.

Relationship of Acute ST-Elevation Myocardial Infarction with hs-CRP and Serum Iron Profile in Southern India: A Cross-sectional Study

Introduction: Cardiovascular diseases are a major cause of mortality. The role of Iron in oxidative myocardial damage remains controversial with multiple studies showing positive and negative correlations. Systemic inflammation is also an important factor in Myocardial Infarction (MI) with high sensitive C-Reactive Protein (hs-CRP) being an important marker. Aim: To investigate the relationship of serum iron and hs-CRP in patients diagnosed with ST-segment Elevation Myocardial Infarction (STEMI) and its role as prognostic indicators. Materials and Methods: A cross-sectional hospital-based study was conducted in which 45 patients were enrolled over a period of two months. Primary variables studied were STEMI and site of infarction as confirmed on echocardiography, hospital stay and patient outcome. Secondary variables were serum iron, hs-CRP, Total Iron Binding Capacity (TIBC), ferritin. Statistical analysis was done using IBM Statistical Package for the Social Sciences (SPSS) software version 20. Mann-Whitney U test, Kruskal Wallis test, ANOVA and Spearman’s rank correlation was used. Results: Iron profile was significantly altered in the various types of MI. Serum iron values lower than 61 mg/dL had a sensitivity of 89% and high Negative Predictive Value (NPV) (95%) for the prediction of mortality in patients. It was seen that significantly lower Unbound Iron Binding Capacity (UIBC) values were seen in patients who died than the survivor group. Low Transferrin Saturation (TS), serum iron, TIBC were associated with a longer hospital stay. About 42 patients showed hs-CRP levels above 0.3 mg/L. High hs-CRP and ferritin values were associated with a prolonged hospital stay. Conclusion: In patients with acute STEMI, serum iron and hs-CRP are shown to be important predictors of morbidity and mortality. Regular iron supplementation with a six monthly hs-CRP monitoring is recommended. Further research shows screening capability is needed.

Abstract P1-10-02: A Novel Attempt To Improve Long-Term Patient Follow-Up in a Low Resource Urban Setting

The lack of either a nationalized health care structure or widespread health insurance in most developing nations is at the root of many of our health care challenges. Amongst them is the loss to follow-up of a majority of patients treated at tertiary care centers. As a consequence, outcomes data from such countries are notoriously non representative. While there have been numerous published reports of treatment outcomes of cancers from India, the reported numbers as a proportion of originally treated patients are probably less than half. We have attempted a simple solution to this problem, made possible primarily by the revolution of low cost mobile cell phones and almost universal access.

Methods.

St. John's Medical College Hospital is a tertiary care centre located in Bangalore, India. We established a patient support group called Aadhara (“Support” in Sanskrit). Aadhara has employed two women with training in counseling and clinical research. Both were provided with cell phones. At the time of initial breast cancer diagnosis, patients are enrolled in a long term follow-up study. Cell phone numbers, address and other contact details of patients and/or next of kin are obtained. The patients and their family are informed about the psycho-social support available at Aadhara that include counseling, psycho-education, talks on psycho-social aspects of the disease, nutrition, news letters, meeting long-term survivors and community breast cancer awareness programs. They are provided phone numbers and email ids to get in touch with the counselors as needed. The patients or their family are contacted by the counselors on a monthly basis. However the patients are free to get in touch with the counselors by just making a “missed call” to the cell phone numbers.

Results

Aadhara has been operational for close to two years. During this period we have enrolled 121 patients into our longitudinal observational study. There have been 11 deaths in our cohort. The most gratifying outcome has been the loss of only 2 patients to follow-up. This represents a greater than 95% follow-up. The costs of this entire program have been made available by a philanthropic organization and are approximately USD 2000 per month. Represented as per patient cost, this is less than USD 20/patient per month and could probably be halved as the enrollments grow. Discussion

The rapid and deep penetration of mobile phone services in India present opportunities for obtaining better metrics of the consequences of medical treatment. This model has the advantage of scalability and diminishing per patient costs as the numbers grow. It is also portable to other clinical conditions where long-term outcomes are needed to guide health care interventions. This is “proof-of-concept” that improved outcome measures can be obtained in low resource settings at costs that are a fraction of the cost of treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-10-02.

Chemical composition of precipitation in the coastal environment of India

The present study investigated the chemical composition of precipitation at Comba, Madgaon, South Goa during southwest monsoon. The rainwater samples were collected on event basis during June-September 2008 and were analyzed for pH, major anions F, Cl, NO(3), SO(4)) and cations (Ca, Mg, Na, K, NH(4)). The pH value varied from 5.36 to 6.91 (6.25 +/- 0.28) indicating alkaline nature of rainwater and dominance of Cl and Na in precipitation. The Neutralization factors (NF) was found to be NFCa = 1.22, NFMg = 0.42, NFNH(4) = 0.37 and NFK = 0.14 indicating below cloud process in which crustal components are responsible for neutralization of anions.

Insulin sensitivity and cardiac autonomic function in young male practitioners of yoga

BACKGROUND

While yoga is thought to reduce the risk of chronic non-communicable diseases such as diabetes, there are no studies on insulin sensitivity in long term practitioners of yoga. We assessed insulin sensitivity and cardiac autonomic function in long term practitioners of yoga.

METHODS

Fifteen healthy, young, male practitioners of yoga were compared with 15 young, healthy males who did not practice yoga matched for body-mass index. Fasting insulin sensitivity was measured in the fasting state by the hyperinsulinaemic-euglycaemic clamp.

RESULTS

There were no significant differences between the groups in their anthropometry or body composition. However, the fasting plasma insulin was significantly lower in the yoga group. The yoga group was also more insulin sensitive (yoga 7.82 [2.29] v. control 4.86 [11.97] (mg/[kg.min])/(microU/ml), p < 0.001). While the body weight and waist circumference were negatively correlated with glucose disposal rate in the controls, there were no similar correlations in the yoga group. The yoga group had significantly higher low-frequency power and lower normalized high-frequency power.

CONCLUSION

Long term yoga practice (for 1 year or more) is associated with increased insulin sensitivity and attenuates the negative relationship between body weight or waist circumference and insulin sensitivity.

Homocysteine induces mesangial cell apoptosis via activation of p38-mitogen-activated protein kinase

Hyperhomocysteinemia is prevalent among patients with chronic kidney disease (CKD) and has been linked to progressive kidney and vascular diseases. Increased glomerular mesangial cell (MC) turnover, including proliferation and apoptosis, is a hallmark of CKD. Activation of p38-mitogen-activated protein kinase (p38-MAPK) has been linked to apoptosis in many cell lines. Accordingly, we studied the effect of homocysteine (Hcy) on MC p38-MAPK signalling and apoptosis. Hcy (50 microM/24 h) increased MC apoptosis as determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) and single-stranded DNA (ssDNA) analysis. In addition to increases in pro-caspase-3 protein and caspase-3 activity, cells exposed to Hcy manifested enhanced reactive oxygen species content. Hcy increased p38-MAPK activity (fivefold), with maximal effect at 50 microM and 20 min; p38-MAPK activation was attenuated by N-acetylcysteine (Nac) and catalase (Cat), further indicating that the effect was via oxidative stress. Confocal microscopy revealed activation and nuclear translocation of p38-MAPK that was attenuated by Cat. In addition, Hcy-induced apoptosis as determined by TUNEL and ssDNA assay was abrogated by Nac, Cat, and SB203580 (p38-MAPK inhibitor). We conclude that in MC, Hcy (i) activates p38-MAPK and increases p38MAPK nuclear translocation via an oxidative stress dependent mechanism and (ii) induces DNA damage and apoptosis that is dependent on oxidative stress and p38-MAPK activation.

Proteomic analysis of homocysteine inhibition of microvascular endothelial cell angiogenesis

Although homocysteine (Hcy) inhibits angiogenesis in vivo and in vitro, the mechanism(s) underlying this phenomenon are largely unclear. The hypothesis of the present work is that Hcy, while inducing the expression of antiangiogenic factors, inhibits the production of angiogenic factors. Mouse brain microvascular endothelial cells (MVEC) were cultured in the presence and absence of 20 microM Hcy for 24 hr in serum-free medium. Cell homogenates were incubated with Trans-Signal Angiogenesis Antibody Array containing antibodies to angiogenic activators (ANG, HGF, leptin, VEGF, IL-6, IL-8, PIGF, FGF-alpha/beta, TNF-alpha and TGF-alpha) and inhibitors (IFN-gamma, IL-12, IP-10, TIMP-1 and -2). The array membranes were scanned and normalized with positive controls. Angiogenesis and formation of capillaries were measured by culturing the MVEC in Matrigels. The capillary-like structures were identified by transmission microscopy. Hcy decreased the expression of leptin, IL-6, -8, PIGF, FGF-alpha and VEGF, while the levels of anti-angiogenic IL-12, IP-10 (chemokine) and TIMP-1 were increased by Hcy. The vascular tube-like structures by MVEC were decreased by increased Hcy. However, the addition of VEGF to Hcy-treated MVEC ameliorated the decreased Hcy-mediated capillary formation. The results suggest that Hcy inhibits angiogenesis, in part, by decreasing VEGF and increasing TIMP-1.

HSP70 and HSP90 expression in leucocytes after exercise in moderately trained humans

In this study, we examined expression of heat shock proteins (HSP) 70 and 90 in human leucocytes after moderate-to-heavy exercise. We also compared baseline levels of HSP70 and HSP90 in trained (TR) and untrained (UT) subjects. Eleven TR subjects ran on a treadmill for 1 h at 70% of maximal oxygen consumption. The HSP levels were measured prior to exercise and 15 and 24 h after exercise. Baseline HSP levels were also measured in eight UT controls. Fifteen hours and 24 h after exercise, TR subjects showed no significant increases in HSP70 (P > 0.05). The HSP90 levels also did not change (P > 0.05). Baseline HSP70 levels in TR subjects were lower than in UT subjects (2.04 +/- 0.51 ng vs. 4.52 +/- 0.95 ng, P < 0.05), while HSP90 levels were similar in TR and UT subjects. We conclude that exercise at an intensity that is within normal limits for a moderately trained individual is not a sufficient stimulus of HSP70 production in leucocytes. We also conclude that blunted levels of baseline HSP70 expression in TR subjects might be a chronic adaptation to training.

Effects of estrogen antagonists and agonists on the ACTH response to restraint stress in female rats

Previous studies have found that female rats are less sensitive than males to hypothalamic-pituitary-adrenal axis feedback inhibition by exogenous glucocorticoid administration. To determine whether estrogen contributes to this sex difference, we examined the effects of the estrogen antagonists tamoxifen and C1628 on the ACTH and corticosterone responses to restraint stress. CI628 increased both the ACTH and corticosterone response to restraint stress, and tamoxifen increased the ACTH response to restraint. Using overiectomized female rats, we also examined the effects of seven days of estradiol and/or progesterone replacement. Low dose estradiol decreased the ACTH but not the corticosterone response to restraint stress while progesterone had no effect on ACTH or corticosterone responses. The combination of estradiol and progesterone also decreased the ACTH response to stress, and the magnitude of the effect did not differ from that found with estradiol treatment alone. These data suggest that in the physiological range estradiol is an important inhibitory factor in the hypothalamic-pituitary-adrenal stress response of females.

Posttransplant administration of donor leukocytes induces long-term acceptance of kidney or liver transplants by an activation-associated immune mechanism

Donor leukocytes play a dual role in rejection and acceptance of transplanted organs. They provide the major stimulus for rejection, and their removal from the transplanted organ prolongs its survival. Paradoxically, administration of donor leukocytes also prolongs allograft survival provided that they are administered 1 wk or more before transplantation. Here we show that administration of donor leukocytes immediately after transplantation induced long-term acceptance of completely MHC-mismatched rat kidney or liver transplants. The majority of long-term recipients of kidney transplants were tolerant of donor-strain skin grafts. Acceptance was associated with early activation of recipient T cells in the spleen, demonstrated by a rapid increase in IL-2 and IFN-gamma at that site followed by an early diffuse infiltrate of activated T cells and apoptosis within the tolerant grafts. In contrast, IL-2 and IFN-gamma mRNA were not increased in the spleens of rejecting animals, and the diffuse infiltrate of activated T cells appeared later but resulted in rapid graft destruction. These results define a mechanism of allograft acceptance induced by donor leukocytes that is associated with activation-induced cell death of recipient T cells. They demonstrate for the first time that posttransplant administration of donor leukocytes leads to organ allograft tolerance across a complete MHC class I plus class II barrier, a finding with direct clinical application.

Effects of atropine and L-NAME on cutaneous blood flow during body heating in humans

We sought to investigate further the roles of sweating, ACh spillover, and nitric oxide (NO) in the neurally mediated cutaneous vasodilation during body heating in humans. Six subjects were heated with a water-perfused suit while cutaneous blood flow was measured with a laser-Doppler flowmeter. After a rise in core temperature (1. 0 +/- 0.1 degrees C) and the establishment of cutaneous vasodilation, atropine and subsequently the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) were given to the forearm via a brachial artery catheter. After atropine infusion, cutaneous vascular conductance (CVC) remained constant in five of six subjects, whereas L-NAME administration blunted the rise in CVC in three of six subjects. A subsequent set of studies using intradermal microdialysis probes to selectively deliver drugs into forearm skin confirmed that atropine did not affect CVC. However, perfusion of L-NAME resulted in a significant decrease in CVC (37 +/- 4%, P < 0.05). The results indicate that neither sweating nor NO release via muscarinic receptor activation is essential to sustain cutaneous dilation during heating in humans.

Effects of nitric oxide synthase inhibition on cutaneous vasodilation during body heating in humans

We sought to examine further the potential role of nitric oxide (NO) in the neurally mediated cutaneous vasodilation in nonacral skin during body heating in humans. Six subjects were heated with a water-perfused suit while cutaneous blood flow was measured by using laser-Doppler flowmeters placed on both forearms. The NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) was given selectively to one forearm via a brachial artery catheter after marked cutaneous vasodilation had been established. During body heating, oral temperature increased by 1.1 +/- 0.1 degreesC while heart rate increased by 30 +/- 6 beats/min. Mean arterial pressure stayed constant at 84 +/- 2 mmHg. In the experimental forearm, cutaneous vascular conductance (CVC; laser-Doppler) decreased to 86 +/- 5% of the peak response to heating (P < 0.05 vs. pre-L-NMMA values) after L-NMMA infusion. In some subjects, L-NMMA caused CVC to fall by approximately 30%; in others, it had little impact on the cutaneous circulation. CVC in the control arm showed a similar increase with heating, then stayed constant while L-NMMA was given to the contralateral side. These results demonstrate that NO contributes modestly, but not consistently, to cutaneous vasodilation during body heating in humans. They also indicate that NO is not the only factor responsible for the dilation.

Kinetics of intragraft cytokine expression, cellular infiltration, and cell death in rejection of renal allografts compared with acceptance of liver allografts in a rat model: early activation and apoptosis is associated with liver graft acceptance

BACKGROUND

Liver transplants in the rat strain combination PVG-to-Dark Agouti are spontaneously tolerated, whereas kidney transplants in the same strain combination are rejected in 7-9 days.

METHODS

To identify organ-specific differences that might yield further information about the mechanism of tolerance induction in this strain combination, liver or kidney grafts, spleen, and draining lymph nodes were harvested at days 1, 3, 5, and 7, and examined by immunohistochemistry, terminal deoxynucleotide transferase-mediated dUTP nick end labeling assay, and reverse transcriptase-polymerase chain reaction for interferon-gamma, interleukin (IL)-2, IL-4, and IL-10.

RESULTS

Renal allograft rejection was associated with the progressive development of an intense mononuclear cell infiltrate. Markers of lymphocyte activation and cytokine up-regulation appeared from day 3, and many apoptotic parenchymal cells were noted on days 5-7, at the peak of rejection. Conversely, liver allograft tolerance was associated with more rapid infiltration by activated T cells and earlier increases in cytokine expression, but with a more limited degree of cellular infiltration. Concurrent with the early activation, high levels of apoptosis were found in areas of leukocyte infiltrate, paralleling the disappearance of activated T cells from the graft between days 3 and 5.

CONCLUSIONS

Apoptosis of infiltrating leukocytes in liver allografts may represent an important process in the induction of spontaneous liver transplant tolerance and may underlie the abortive nature of the effector response observed within tolerated livers. In contrast, activated cells in renal allografts in the same strain combination survive and proliferate, express high levels of cytokines, and are efficient in bringing about graft destruction.