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Biomedical subjects

A Kumar

Publications and source records attributed to A Kumar.

At least 1,459 records · Page 81Linked to original sources
PubMed1991

A study of the effect of high concentrations of fluoride on the reproductive organs of male rabbits, using light and scanning electron microscopy.

Fluoride was orally administered to rabbits at 10 mg NaF/kg body weight for 18 or 29 months. The animals were then killed and the structure of the testis, epididymis and vas deferens studied under light and scanning electron microscopes. In animals treated for 29 months, the spermatogenic cells in the seminiferous tubules were disrupted, degenerated and devoid of spermatozoa. In animals treated for 18 or 29 months, loss of cilia on the epithelial cells lining the lumen of the ductuli efferentes of the caput epididymidis and of stereocilia on the epithelial cells lining the lumen of the vas deferens was observed. In some regions of the epithelial lining of the lumen of the ductuli efferentes and vas deferens, the boundaries of the cells were not clear and appeared to be peeled off. Mucus droplets were abundant in the vas deferens of control animals, but absent in both the treated groups. Spermatogenesis ceased only in animals treated for 29 months. The difference in the structural changes observed in the testes of the 2 treated groups may have been due to the blood-testis barrier. It is concluded that ingestion of high concentrations of fluoride has harmful effects on the male reproductive system.

Animals↗
PubMed1991

Divergent nystagmus: recordings from an advanced system of infra-red oculography.

Because of some limitations in photoelectric nystagmography, a new system of binocular infra-red oculography (BIRO) was developed. The advantages of BIRO are excellent linearity up to +/- 20 degrees horizontal eye movement, sensitivity of at least 0.1 degree of eye movement and the possibility of obtaining binocular recordings. In the course of a routine clinical evaluation, divergent nystagmus was recorded in 2 patients. This occurred both spontaneously and following caloric stimulation. A vascular brain stem pathology was strongly suspected from magnetic resonance imaging (MRI) studies. The possible mechanisms of divergent nystagmus are discussed.

Brain↗
PubMed1991

Protective immunity to entamoeba histolytica infection in subjects with antiamoebic antibodies residing in a hyperendemic zone.

To investigate the relationship between amoebic gut infection and the presence of serum antiamoebic antibodies in a community where amoebiasis is highly endemic, a cross-sectional population survey was conducted covering 982 subjects in 2 adjacent villages in rural India. E. histolytica was detected in fecal smears in 18.1% (88/487) and antiamoebic antibodies by micro-ELISA in 28.7% (251/874) subjects. In 450 subjects in whom there was no clinical evidence of invasive amoebic disease or history of ingestion of antiamoebic drugs in the previous year and from whom both stool and matched serum samples were obtained, correlation of gut infection with seropositivity was attempted. Seropositivity in 80 cyst passers (23.8%) was significantly lower than in 370 non-cyst passers (35.1%; p less than 0.05). Conversely the rate of gut infection with E. histolytica was lower in seropositive subjects (19/149; 12.8%) as compared to seronegative subjects (61/301; 23%, p less than 0.05). In the population where E. histolytica infection was highly endemic, the rate of gut infection with the parasite was inversely related to seropositivity. Our data suggests that invasive E. histolytica infection (mostly asymptomatic) evokes good gut immunity in the host with clearing of the parasite from the colon and/or resistance to reinfection. High prevalence rate of amoebic antibodies indicates good "herd" immunity.

Adolescent↗
PubMed1991

Evaluation of microbial metabolites for trypanocidal activity: significance of biochemical and biological parameters in the mouse model of trypanosomiasis.

Trypanosomiasis is a parasitic disease, prevailing in both humans and animals, caused by a single-cell parasite, Trypanosoma spp. Three microbial metabolites, namely antiamoebin, F-857 and 6-MFA, were evaluated for trypanocidal activity by using a mouse model of trypanosomiasis, which is caused by T. evansi. The significance of the biological and biochemical parameters with respect to physio-pathology of trypanosomiasis and their implications in the evaluation of new trypanocidal compounds were discussed.

Animals↗
PubMed1991

Approaches to higher productivity in health care system.

The prosperity of organisations is recognised as being dependent on their comparative productivity. Productivity expresses a relationship between outputs from a system and the inputs which go into this creation. Hospital activities have to be assessed. Results have to be evaluated. The medical and paramedical staff have to quantify procedure and assess them qualitatively in order to improve the standards of care. Assessment techniques already introduced in many hospitals have succeeded in reducing the number of antibiotics (and their cost) and the amount of blood used in certain operations and also cutting the wait for operations. As long as there is unused capability in the individual or the productive system, increases in productivity can be achieved without decline in quality. If one focuses on quality while holding speed constant, quality should improve, waste should be eliminated, and productivity should increase. This can happen as long as the individual, or group of individuals, is willing to exert effort and has the capacity to achieve the quality--productivity levels desired. It is the operations manager's task to provide the facilities, tools and desired (motivation) to do so.

Efficiency↗
PubMed1991

Interaction of human immunodeficiency virus type I Rev protein with nuclear scaffold nucleoside triphosphatase activity.

Human immunodeficiency virus type I encodes a regulatory protein, termed Rev, which is associated with the appearance of unspliced and partially spliced viral RNAs in the cytoplasm. Rev is believed to function via interaction with a sequence element in the env region of the viral RNA, termed the Rev-responsive element (RRE). In this study, we use a stably transfected, Rev-producing mouse cell line to show that low, functional levels of Rev are associated with the nuclear scaffold (NS). Immunohistochemical studies localize Rev to the NS. Furthermore, immunoblot analyses demonstrate the presence of Rev in NS preparations isolated from Rev-producing cells and document binding of purified Rev protein to isolated NS or to cloned lamin C in vitro. Results with an in vitro RNA transport assay suggest that Rev is associated with a significant defect in transport of RNAs which lack RRE, whereas transport of RRE-containing transcripts proceeds efficiently. This Rev-induced transport defect appears to be mediated via direct inhibition of NS nucleoside triphosphatase, an enzyme thought to be involved in the nucleocytoplasmic transport process. NS preparations isolated from Rev-producing cells show a significantly lower nucleoside triphosphatase activity than those from control preparations. Addition of Rev protein to isolated NS produces a significant inhibition of NS nucleoside triphosphatase activity, which is specifically reversed by addition of RRE transcripts. These data suggest that a major aspect of Rev function may involve selective modulation of host cell nucleocytoplasmic transport mechanisms via interaction with the NS.

Animals↗
PubMed1991

Juvenile nasopharyngeal angiofibroma.

A total of 27 cases of nasopharyngeal angiofibroma were treated in this series. All were males and age ranged between 9 and 24 years. Predominant symptoms were epistaxis and nasal obstruction. Nasopharyngeal mass was present in all cases. Cheek extensions were observed in 6. Surgery was done in 25 cases. Transpalatal excision was done in all cases. Cheek extensions were removed through separate sublabial incisions. Additional lateral rhinotomy was required in one case. Death occurred in one case during surgery due to excessive haemorrhage. Out of 25 cases, 21 were followed up for periods ranging from 2-5 years. Complete cure was observed in 16 cases. Recurrence occurred in 5 cases, who were operated upon again. Out of 5 recurrence operated cases, 2 cases showed a second recurrence.

Adolescent↗
PubMed1991

Involvement of adrenergic & cholinergic mechanisms in analgesia electrically induced from pretectal nucleus of rat.

Analgesia induced by pretectal stimulation in rat was analysed using suitable antagonists. Mild electrical stimulation of sites in the pretectal nucleus (PTN) caused analgesia of long duration, without signs of aversion and unassociated with motor deficit. Pretreatment of animals with ip atropine sulphate (1 mg/kg), phenoxybenzamine (5 mg/kg), sotalol (2 mg/kg) and haloperidol (1 mg/kg) but not with saline, markedly reduced the antinociceptive response to PTN stimulation. Mild PTN stimulation thus seems to induce potent and long lasting analgesia in rats probably involving multisynaptic antinociceptive pathway(s).

Analgesia↗
PubMed1991

Effect of high dose intravenous pulse dexamethasone on lymphocyte phenotypes.

The lymphocyte phenotypes were enumerated in 10 patients with collagen diseases at 0 h, 4 h, 24 h and 7 days after a megadose (100 mg) iv pulse dexamethasone. A significant decrease in CD3 (from a mean of 2324.3/mm3 to 705.9/mm3) and CD4 (from a mean of 1642.6 to 317.6/mm3) cells was observed at 4 h, which recovered partially by 24 h (186.7 and 1226.3/mm3 respectively) and completely at 7 days (2496.1 and 1838.4/mm3). A transient decrease in CD8 cells at 4 h was also observed. There was no significant effect on B cells.

Adolescent↗
PubMed1991

Functional bladder neck obstruction in females--a revisit.

Functional bladder neck obstruction is supposed to be nonexistent or a very rare clinical disorder. In the past two and a half years, detailed synchronous, video pressure flow EMG studies were done in all the female patients who had evidence of obstructed voiding, poor flow and acute or chronic retention. The subjects of this study are nine females who had high sustained detrusor pressure, high opening pressure, low uroflow and silent sphincter during pressure-flow EMG study. A simultaneous urovideo recording showed either a closed bladder neck, inadequate funneling, intermittent or improper opening during voiding (when Pdet was high and sustained). These patients did not have any anatomical urethral obstruction, neurogenic disorder or systemic disease (like diabetes) affecting voiding. This stringent criteria of functional bladder neck obstruction was observed in nine patients. Five patients had acute or chronic retention and three patients had varying degree of renal failure. Initially all patients were managed by clean intermittent self catheterisation (CIC). Alpha blockers were empirically tried in six patients and had shown variable results. Bladder neck incision (BNI) was performed in two patients with rewarding success.

Adrenergic alpha-Antagonists↗
PubMed1991

Effect of recombinant human granulocyte colony-stimulating factor administration in normal and experimentally infected newborn rats.

We investigated the effects of repetitive recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration at three different doses (every 12 h times six doses, starting at 12-24 h of age) on the kinetics of neutrophil production in Sprague-Dawley rats. We determined WBC counts, differentials, the number of total nucleated cells, the myeloid mitotic pool cells (promyelocytes and myelocytes), the storage pool cells (metamyelocytes, bands, and polymorphonuclear cells [PMNs]) and the granulocyte-macrophage (granulocyte-macrophage colony-forming units, CFU-GM) and macrophage (macrophage colony-forming units, CFU-M) progenitor cells of the bone marrow, spleen, and the liver before the first dose of rhG-CSF administration and 12 h after the second, fourth, and sixth dose. Control animals were given the diluent by the same schedule. Recombinant human G-CSF-treated rats showed a significant dose-dependent increase in the number of total WBC and neutrophil counts at all time points compared to control rats. The total number of CFU-GM and myeloid mitotic pool cells (marrow plus spleen plus liver) progressively increased with age in both control and G-CSF groups, but the G-CSF treated groups showed a significantly larger number of mitotic pool cells at hour 24, continuing up to hour 72, compared to the control group. However, there was no significant difference at any time point in the number of CFU-G/GM as detected by the granulocyte-macrophage colony-stimulating factor (GM-CSF)-supported culture system. Priming of newborn rats with injections every 12 h of rhG-CSF times two doses, or six doses followed by inoculation of group B streptococci (GBS) did not significantly change the sepsis death rate of animals, although the neutrophil counts in infected rhG-CSF-primed animals were significantly larger than the infected control animals. Injection of human i.v. gammaglobulin 3 h following inoculation with GBS significantly improved the survival of animals compared to G-CSF administration or administration of the diluent alone (control). Thus G-CSF alone may not be beneficial for the treatment of neonates with sepsis. Additional work is needed to determine whether combination of G-CSF with antibiotics or other cytokines, such as GM-CSF or interleukin 6 (IL-6) may be of benefit.

Animals↗
PubMed1991

Towards the design of heterovalent anti-malaria vaccines: a hybrid immunogen capable of eliciting immune responses to epitopes of circumsporozoite antigens from two different species of the malaria parasite, Plasmodium.

The peptide CS.T3, corresponding to residues 378-398 of the Plasmodium falciparum (Pf) circumsporozoite (CS) protein sequence (except with cysteines 384 and 389 replaced by alanines), has been found to be almost universally recognized by human and mouse T lymphocytes. When colinearly linked to the repetitive B-lymphocyte-specific epitope (Asn-Ala-Asn-Pro)n of Pf CS protein, CS.T3 induces T-helper activity for an anti-(Asn-Ala-Asn-Pro)n antibody response in mice of different haplotypes. We constructed a double-epitope peptide, CS.T3-R3, by co-linearly joining a truncated 18-mer form (IEKKIAKMEKASSVFNVV) of CS.T3 to three tandem repeats (R3) of a B-cell-specific epitope, QGPGAP, of Plasmodium yoelii (Py) CS protein, via a two-glycine spacer. Whereas CS.T3 and R3 did not induce specific antibodies, CS.T3-R3 elicited anti-CS.T3 and anti-R3 antibodies in different mouse strains. Some human anti-Pf sera from malaria-endemic areas contained high-titred anti-CS.T3 antibody IgG, indicating that parasite-derived CS.T3 contains a B-cell determinant which is maintained in the alanine-substituted synthetic CS.T3. Antibody absorption experiments showed that CS.T3-R3 contains no new B-cell-specific determinants other than R3 and CS.T3. That the Pf CS protein epitope, CS.T3, supports T-cell help for antibody responses against the Py CS protein repeat epitope, QGPGAP, implies the possible use of CS.T3 in anti-sporozoite multiple-epitope vaccines against different species of Plasmodium. Colinearly linking CS.T3 to R3, via a two-glycine spacer, appears to be a useful model by which different T- and B-cell-specific determinants can be jointed into a heterovalent immunogen while retaining their distinct immunological properties.

Animals↗