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Biomedical subjects

V Kumar

Publications and source records attributed to V Kumar.

At least 163 records · Page 9Linked to original sources

Aggressive gluten challenge of dermatitis herpetiformis cases converts them from seronegative to seropositive for IgA-class endomysial antibodies.

The responses to aggressive gluten challenge of two dermatitis herpetiformis patients with normal gut mucosa and negative serum findings for IgA endomysial antibodies while on normal diets indicate that these patients have a latent gluten-sensitive enteropathy. This was shown further by the control of skin lesions in both cases and in one case by the clearance of the induced gut lesions with a gluten-free diet. Specifically, for 12 to 20 weeks, aggressive gluten challenge (1 to 2 gm/kg/day) of these two patients was followed by both the appearance of and a rise in titer of IgA endomysial antibodies with an exacerbation of skin lesions. After 27 weeks of gluten challenge, histologic studies of the gut showed grade III flattening of the jejunal mucosa in the patient who developed IgA endomysial antibodies 19 weeks before biopsy was performed but not in the patient in whom IgA endomysial antibodies appeared 7 weeks before biopsy was performed. When both patients were placed on a gluten-free diet, IgA endomysial antibodies titers showed negative findings and the skin lesions subsided. It was possible to discontinue dapsone treatment after 30 weeks on a gluten-free diet in one patient and after 33 weeks in the other. It is important to note in the patient who developed grade III (significant) gut pathology after gluten challenge that a third biopsy taken 59 weeks after starting a gluten-free diet revealed a return to a grade II (insignificant) level of villus atrophy. Thus if sulfones are contraindicated in such cases, patients can be treated successfully with a gluten-free diet.

Child

Comparison of psychologic and cognitive functions after general or regional anesthesia.

The behavior of 105 patients randomly assigned to receive either general or regional anesthesia and who underwent one of three types of surgery (hysterectomy, prostatectomy, or joint replacement) was assessed before, immediately after, and 3 mo after surgery. Psychologic status was assessed by the Sickness Impact Profile, the SCL-90-R, and a Metamemory Questionnaire. Cognitive functioning was measured by a battery of ten psychomotor, memory, and skilled performance tasks. Physical health was scored by the ASA classification of physical status, a health index, postoperative complications ratings, and a self-rated measure of the patient's health. There were cognitive differences across surgery groups due to age and gender variability among the patients; however, the type of anesthesia produced no difference in behavior. Both the physical and mental health indices showed improvement from the preoperative to the postoperative periods. General anesthesia appears to pose no risk to mental function and recovery beyond that associated with regional anesthesia and surgery.

Adult

Phenotypic heterogeneity and cytotoxic activity of Con A and IL-2-stimulated cultures of mouse Thy-1+ epidermal cells.

Short-term and long-term cultures of mouse Thy-1+ epidermal cells (EC) were established in order to characterize their phenotypic and functional properties. Concanavalin A (Con A) and Interleukin 2 (IL-2) stimulated Thy-1+ EC mediated non-MHC directed cytotoxicity preferentially against the NK-sensitive target, YAC-1 vs the NK-resistant target, P815; these cells also mediated antibody-dependent cell-mediated cytotoxicity (ADCC), indicating the presence of IgG-FcR on at least some of them. Freshly isolated Thy-1+ EC failed to lyse YAC-1 targets; however, this activity was observed after 9 d of culture with Con A and IL-2. While dendritic Thy-1+ EC, in vivo, do not express the T-cell markers, L3T4 and Lyt-2, short-term cultured cells displayed phenotypic heterogeneity with small but significant percentages of Lyt-2+ and L3T4+ cells appearing transiently. The phenotype of the effector cell(s), which mediates cytotoxic activity, was determined by utilizing flow cytometry to sort short-term cultured EC into positively and negatively stained populations. Cells which express L3T4, or which lack asialo GM1, did not lyse YAC-1 targets; maximum cytotoxic activity was found within populations of cells which are asialo GM1+, Lyt-2-, and asialo GM1+, Lyt-2+. These studies indicate that Thy-1+ cells derived from mouse epidermis when cultured in the presence of Con A and IL-2 have the capacity to generate a phenotypically heterogeneous population, some cells of which are capable of mediating cytotoxic activities.

Animals

Mechanism of anti-asialo GM1 prevention of graft-vs-host disease: identification of allo-antigen activated T cells.

The purpose of this study was to begin to dissect the mechanism whereby anti-asialo GM1 (alpha ASGM1) prevents otherwise lethal graft-vs-host disease (GVHD) across multiple minor histocompatibility barriers in mice. Phenotypic characterization of cells from the peak proliferative time of the graft-vs-host reaction (C57BL/6J lymph node cells----irradiated LP/J, days 5-7) revealed the alpha ASGM1 and alpha Thy 1.2 identified cells with an approximate 80% concordance and that NK-1.1 staining was negligible. Because resting T cells do not label with alpha ASGM1, the epitope recognized by alpha ASGM1 on GVHR T cells is an activation antigen. Because asialo GM1 has been previously found on the surface of activated macrophages, we wanted to distinguish between the two most likely targets for the in vivo effect of alpha ASGM1 infusions (T cells or macrophages). We compared the effects of alpha ASGM1 infusions on alloantigen-stimulated T-cell proliferation versus antigen presentation: T-cell proliferation was markedly reduced by alpha ASGM1 infusions, whereas antigen presentation function was not diminished. We conclude that the mechanism whereby alpha ASGM1 prevents GVHD does not involve NK cells or antigen presenting cells, but does involve activated donor T cells. The potential therapeutic advantage of such an antibody for use in human disorders compared to pan-immunosuppression lies in its ability to eliminate selectively those T cells involved in the immunologic process (i.e. activated T cells) while sparing the remainder of the T-cell repertoire.

Animals

An analysis of critical incidents in a teaching department for quality assurance. A survey of mishaps during anaesthesia.

A prospective survey was conducted from April 1984-January 1985 and April 1985-January 1986 to study the frequency of critical incidents and factors associated with them. Eighty-six mishaps were reported in the first period, the majority of which were because of human error (80.3%); the most common were the transmission of gases and vapours and errors in drug administration. Factors frequently associated with these mishaps were failure to perform a normal check and lack of familiarity with equipment or technique. An anaesthesia equipment checklist was incorporated in the survey during the second period and 43 mishaps were reported. This decrease in incidence may have resulted from the anaesthesia apparatus checklist, awareness of mishaps since they were discussed regularly at departmental meetings, and new anaesthesia machines (eight older machines were replaced during the first period and 11 at the beginning of the second).

Accidents

The dynamics of quadrupedal locomotion.

This paper presents a dynamical analysis of quadrupedal locomotion, with specific reference to an adult Nubian goat. Measurements of ground reaction forces and limb motion are used to assess variations in intersegmental forces, joint moments, and instantaneous power for three discernible gaits: walking, running, and jumping. In each case, inertial effects of the torso are shown to dominate to the extent that lower-extremity contributions may be considered negligible. Footforces generated by the forelimbs exceed those exerted by the hindlimbs; and, in general, ground reactions increase with speed. The shoulder and hip dominate mechanical energy production during walking, while the knee plays a more significant role in running. In both cases, however, the elbow absorbs energy, and by so doing functions primarily as a damping (control) element. As opposed to either walking or running, jumping requires total horizontal retardation of the body's center of mass. In this instance, generating the necessary vertical thrust amounts to energy absorption at all joints of the lower extremities.

Animals

Identification of IgA subclasses in skin of dermatitis herpetiformis patients.

There is a controversy as to the origin and to the subclass of IgA in dermatitis herpetiformis (DH) skin. The present study was undertaken to reexamine the subclasses of IgA and the presence of J-chain in biopsies of DH patients. Skin biopsies from 12 DH patients were examined for IgA, its subclasses and for J-chain by a modified direct immunofluorescence (IF) method. All DH skin biopsies were positive for IgA. Ten of the twelve biopsies were positive for IgA1. IgA2 was detected in only 3 cases, notably in those which gave the strongest IgA reactions. In general, the fluorescent staining intensity for IgA2 was weaker than IgA1 and IgA1 was less than the total IgA. This may be due to differences in the concentrations of the immunoglobulin subclasses in the skin and may also be due to the restricted specificity of antisera used in the study. Direct IF studies of the presence of J-chain yielded negative findings in all DH cases examined including those which were positive for IgA2. The higher frequency of IgA1 over that of IgA2 and the absence of J-chain indicate that the IgA immune deposits in the DH skin may not necessarily be of mucosal origin.

Dermatitis Herpetiformis

Ultrastructural studies of peripheral nerves in lepromatous leprosy patients.

Ultrathin sections of the peripheral nerves taken from three lepromatous leprosy patients (One untreated, other treated and third in ENL reaction) was examined in the electronmicroscope. In the untreated patient, solid M. leprae organism inside the schwann cell and the degeneration of schwann cell was seen. In contrast, the treated patient showed the degeneration of bacilli and myelinated fibres. However, the characteristics of cells in the ENL reaction showed close similarities with the untreated case.

Humans

Kinetics and location of bone marrow cell graft rejection by irradiated mice.

Natural killer (NK) cells were eliminated with rabbit anti-Asialo GM1 (anti-ASGM1) serum to test the kinetics and location of bone marrow cell (BMC) rejection. Anti-ASGM1 serum was injected intravenously in mice at various times before or after irradiation (8.6 Gy) and transfer of parental-strain or allogeneic BMC. Growth of BMC was determined by measuring splenic 5-iodo-2'-deoxyuridine-125I incorporation 5 days after cell transfer. Anti-ASGM1 serum weakened hybrid resistance even if injected intravenously as late as 24 h post-BMC transfer and even in recipients injected with polyinosinic:polycytidylic acid so as to boost NK activity. If regenerating spleen cells (higher rate of cell cycling) were used as donor cells instead of BMC, the length of time required for rejection was unaffected. Anti-ASGM1 serum injected intravenously rapidly inhibited splenic NK activity and lung clearance of YAC-1 tumor cells, but when injected intratracheally, it only inhibited lung NK activity. Thus, BMC rejection occurs in the hematopoietic tissue and requires at least 24 h.

Animals

Cortisol responses to cholinergic drugs in Alzheimer's disease.

Patients with Alzheimer's disease participated in a trial of two sessions in which they received physostigmine and neostigmine in a double-blind crossover design. Most of these patients subsequently participated in a scopolamine vs saline double-blind crossover trial using a similar design. Physostigmine increased plasma cortisol relative to neostigmine, with the greatest difference at time points greater than 90 min post drug oral administration. Physostigmine also significantly decreased plasma cholinesterase (ChE). There was a significant positive correlation between the effects of physostigmine on increasing cortisol and decreasing ChE; there was no correlation between the increase in cortisol of cholinesterase inhibitor following neostigmine administration, but neither of these chemical parameters is related to the drug's effects on cognitive functioning.

Aged

Function of microtubules under inadequate protein diet.

Microtubules from pancreas have been isolated and estimated. It was found that rats fed with lysine and threonine deficient diet have profoundly lowered levels of microtubules as compared to rats fed either with lysine and threonine supplemented diet or a casein diet at 20% protein level, implicating the role of dietary protein in microtubule assembly. Levels of microtubules in turn may influence the turnover of phosphatidyl inositol as well as release of insulin from pancreas.

Animals

Scl-70 antigen stability and its effect on antibody detection in scleroderma.

We examined 38 patients with scleroderma, 10 with systemic lupus and 10 normal subjects for Scl-70 antibodies by the gel precipitation and by the immunoblot methods. Increased incidence of Scl-70 antibodies in scleroderma were found by the immunoblot method (55%) compared to the gel precipitation methods (40 or 42% depending on the test kits used). Immunoblot analysis of the antigen prepared with 4.0 M NaCl extraction of rabbit thymus acetone powder revealed antigen to be 100, 86, 80 and 70 kDa. However, mainly a single band of 70 kDa was obtained upon extraction of rabbit thymus with 0.3 M NaCl and of calf thymus antigen. Our data support the suggestion that different molecular species of the Scl-70 antigen have variable binding affinities to nuclear DNA. We suggest that the presence of various molecular forms of the antigen may be a result of this differential binding affinity to DNA and the partial proteolytic digestion of 100 kDa from the antigen as reported by others.

Adult