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Biomedical subjects

K Mohan

Publications and source records attributed to K Mohan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Generation of reactive oxygen species by blood monocytes during acute Plasmodium knowlesi infection in rhesus monkeys.

The status and kinetics of monocyte activation during acute P. knowlesi infection was investigated by latex-induced, luminol-dependent chemiluminescence (CL) response. The contribution of various reactive oxygen species (ROS) to CL response was estimated before infection and at peak parasitaemia (day 7 post infection) by using scavengers of ROS (benzoate, catalase and superoxide dismutase). The chemiluminescence index (CLI) was not found to be significantly different from controls on day 2 postinfection, but was significantly higher on days 5 and 7 postinfection. Hydroxyl radical (OH.) production was considerably elevated, whereas superoxide anion (O2-.) and hydrogen peroxide (H2O2) production dropped following infection. These changes in generation of ROS are discussed in relation to the progression of parasitaemia to high levels, immunopathology and immunosuppression during acute P. knowlesi infection.

Animals↗
PubMed1992

Plasmodium falciparum induced perturbations of the erythrocyte antioxidant system.

Erythrocyte antioxidants catalase, superoxide dismutase, reduced glutathione and glutathione peroxidase were studied in cells harbouring different growth stages of Plasmodium falciparum. Catalase and superoxide dismutase showed significant decrease during parasite maturation indicating hampered metabolism of hydrogen peroxide and superoxide anions. Glutathione peroxidase also exhibited a downward trend during the growth of P. falciparum, while there was a moderate accumulation of reduced glutathione. These findings suggest decreased utilization of the reduction potential in detoxification of reactive oxygen species. The fall in all three antioxidant enzymes studied was highly significant (P less than 0.001) in erythrocytes with mature stages of the parasite (trophozoites, schizonts). The increased vulnerability of erythrocytes to damage, which parallels the growth phases of the parasite emphasizes the need for early treatment of P. falciparum malaria to minimise red cell destruction and the resulting anaemia.

Animals↗
PubMed1992

Oxidative damage of erythrocytes infected with Plasmodium falciparum. An in vitro study.

The extent of reduced glutathione, activity of glutathione peroxidase, amount of membrane lipid peroxidation products, and the extent of hemoglobin release from host erythrocytes during in vitro Plasmodium falciparum growth was studied. Highly synchronized parasite cultures were studied to examine the alterations caused by different growth stages of the parasite. There was a moderate increase in the reduced glutathione content as the parasite matured, which was significant only in schizont-rich erythrocyte lysates (p < 0.05) whereas the activity of glutathione peroxidase was significantly low in all the parasitized red blood cells (ring-infected RBC, p < 0.005; trophozoite- and schizont-infected RBC, p < 0.001). The lipid peroxidation product, malonyldialdehyde, of the host red cells increased gradually to more than fourfold in schizont-rich cells as compared with normal erythrocytes (p < 0.001). The hemoglobin release from cultured cells was significantly higher in all parasitized red cell cultures as well as in uninfected cells kept in in vitro, as compared with normal erythrocytes. The consequence of such changes induced by the malarial parasites in the host red cells in the pathogenesis of erythrocyte destruction and anemia of P. falciparum malaria is discussed.

Erythrocytes↗
PubMed1992

An outbreak of haemorrhagic septicaemia (septicaemic pasteurellosis) in cattle in Zimbabwe.

An outbreak of haemorrhagic septicaemia caused by Pasteurella multocida in beef cattle in Zimbabwe grazing effluent-irrigated pastures, is described. The outbreak occurred during the wet summer months and predisposing stress factors included excessive rainfall and unusual cold weather during the preceding month. History, clinical features and post-mortem findings were consistent with reports of the disease from other countries, except that meningitis was also a constant feature. Morbidity approached 77% and mortality 5 per cent. Prophylactic treatment and vaccination with a killed bacterin together with a return of warmer and drier weather were probably important in halting the outbreak.

Age Factors↗
PubMed1992

Effect of nifedipine treatment on oxidative metabolism of peritoneal macrophages and neutrophils of Plasmodium berghei-infected mice.

The oxidative metabolism of peritoneal macrophages (PM) and neutrophils from nifedipine (calcium channel blocker)-treated, Plasmodium berghei (NK 65)-infected and normal infected Swiss Albino mice was studied. A significant fall in oxidative metabolism as evidenced by decreased chemiluminescence (CL) response (P less than 0.001) was recorded both in PM and neutrophils from nifedipine-treated mice compared to the control animals. When the oxidative metabolism of these phagocytes was studied after infection of the host, higher CL response was recorded from both PM and neutrophils isolated during the early course of infection (0-1 and 5-10% parasitaemia) when compared to uninfected mice (P less than 0.001). A similar pattern was observed in the case of nifedipine-treated and infected mice even though the CL response was much lower. The increasing parasite load not only resulted in subnormal CL response but also prolonged the time required for the phagocytes to exhibit peak oxidative activity both in normal infected and CCB-treated infected mice, but the time taken to show peak CL response was shortened following drug administration compared to controls. These observations revealed the profound in vivo effect of CCB on the functioning of phagocytic leucocytes and thereby questions the use of CCB in combination with chloroquine for reversal of drug resistance.

Animals↗
PubMed1992

Mycoplasma ovipneumoniae infection in Zimbabwean goats and sheep.

The prevalence of Mycoplasma ovipneumoniae (MO) in three Communal Lands flocks of goats on the outskirts of Harare is described. In a single sampling of nasal swabs from 172 randomly selected, apparently healthy goats, 112 animals were identified as carriers of MO. The three flocks had a history of occasional deaths, following chronic and subacute pneumonia associated with isolation of MO as the only identifiable pathogen. Attempts to induce clinical pneumonia in groups of 6 to 8-week-old kids and lambs with local isolates of MO were not successful. However, MO was consistently cultured from the trachea, lungs, lymph node and thymus of some test animals. Cuffing interstitial pneumonia was also observed in these animals. Infection of the thymus occurred; this has not previously been reported with any Mycoplasma sp. The animals did not produce detectable serum antibodies to MO nor were they reactive to MO antigen in a tuberculin-type hypersensitivity test. The possibility that a state of immunotolerance may have been responsible for failure to develop clinical pneumonia is discussed.

Animals↗
PubMed1992

Herpes simplex virus-2 (HSV-2) type-specific antibody correlates of protection in infants exposed to HSV-2 at birth.

Western blot analysis was used to compare the herpes simplex virus (HSV)-2 antibody profiles of 40 infants less than 2 wk of age who had been exposed to maternal genital HSV-2 at birth. 4 mothers were HSV seronegative at delivery and seroconverted to HSV-2 ("primary infection"), 9 had HSV-1 antibodies and seroconverted to HSV-2 ("nonprimary first episode infection"), and 27 were HSV-2 seropositive ("recurrent infection"). Neonatal herpes infections developed in 1 of 4 infants of women with primary infection, in 3 of 9 infants of women with nonprimary first episode infection, and in none of the 27 infants of women with recurrent HSV-2. Antibodies to HSV-2 proteins gG-2, VP5, and ICP35 were detected in 83, 89, and 72% of the 36 uninfected infants, respectively. None of the four infected infants had detectable antibodies to gG-2 and only one (25%) had antibodies to VP5 or ICP35. The more limited profiles of the 13 infants born to mothers with first episodes of HSV-2 were then analyzed separately; these profiles were similar among infected and uninfected infants except for gG-2, which elicits antibodies that are type specific for HSV-2. None of the infected infants versus seven of nine (78%) uninfected infants were gG-2 seropositive. These comparisons suggest that maternal type-specific antibodies may play a role in preventing neonatal infection after exposure to HSV-2.

Antibodies, Viral↗
PubMed1989

Uremic optic neuropathy.

A rare case of documented reversible bilateral optic neuropathy as the presenting manifestation of chronic renal failure is discussed. Repeated hemodialysis in the early stages of the disorder was useful for recovery of vision.

Adult↗
PubMed1989

Congenital cyst of Krause's gland.

Cysts of Krause's glands usually occur as retention cysts in cicatricial conditions of the conjunctiva. We report a rare case of congenital cyst of Krause's gland in a 2-year-old boy.

Child, Preschool↗
PubMed1989

Giant cell tumour of ilium.

Most common tumours of ilium are chondrosarcoma and reticulum cell sarcoma. Giant cell tumour commonly presents at the ends of long bones. It is quite uncommon to find osteoclastoma in flat bones, especially ilium. This is the only case of osteoclastoma of ilium seen during the last 7 years in this institution and is reported for its rarity.

Bone Neoplasms↗
PubMed1988

Nosocomial transmission of rotavirus infection.

Children admitted to the infant ward between November 30, 1983, and May 5, 1984, were sampled for rotavirus antigen at admission and at 4-day intervals during subsequent hospitalization. Rotavirus was detected in 51 of 315 infants, 24 at the initial sampling and 27 after 72 hours of hospitalization (nosocomial cases). Forty-one of the cases were symptomatic and 10 were asymptomatic. Nosocomial rotavirus was detected in 5, 13 and 24% of children in the hospital for 4 to 8, 9 to 13 and greater than 13 days, respectively. Attending physicians clinically entertained the diagnosis of rotavirus infection in 58% of community-acquired cases but in only 22% of nosocomial cases. Subgrouping of 24 of the rotavirus isolates with monoclonal antibodies indicated that two-thirds of the isolates were Subgroup II, and the remainder were a mixed subgroup, with similar prevalences in the nosocomial and community-acquired cases. Only 11 of 27 instances of nosocomial rotavirus acquisition were epidemiologically associated with a rotazyme-positive roommate and in 4 of these instances different subgroups were present in the 2 roommates. These data suggest that infected roommates appear not to be a major source for direct transmission of nosocomial rotavirus infection.

Antigens, Viral↗
PubMed1988

Internal fixation in 50 cases of Galeazzi fracture.

Fifty Galeazzi fracture dislocations were treated by early open reduction, internal fixation, and cancellous bone grafting. After 1 year, 40 cases were good, 8 fair, and 2 poor. We conclude that early open reduction and rigid internal fixation reestablishes the normal relationship of the fractured fragments and the distal radioulnar joint without repair of the ligaments.

Adolescent↗
PubMed1987

Ocular and orbital metastasis from systemic malignancies.

One hundred and seventy adult patients and one hundred and forty-eight children with systemic malignancies were examined for ocular and/or orbital metastases. Thirty-six patients (11.3%) had intraocular and/or orbital metastasis. Twenty-nine of the 36 patients (80.5%) had orbital metastasis, five patients (13.9%) had intraocular and two patients (5.5%) had intraocular and orbital metastasis. The commonest malignancy producing ocular metastasis was carcinoma breast in females and carcinoma bronchus in males. Eight of the 17 children had orbital deposits from leukaemia (47%) and six from neuroblastoma (35%). One child had uveal infiltration from acute lymphatic leukaemia. Ophthalmic metastasis were treated by external irradiation and/or combination chemotherapy whenever possible. The mean survival was five months for intraocular metastasis and 15.6 months for the orbital metastasis in adults. Prognosis was very poor in children.

Adult↗