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Biomedical subjects

M Z Khan

Publications and source records attributed to M Z Khan.

At least 55 records · Page 3Linked to original sources
PubMed1994

Retrospective studies on the measurements, karyotyping and pathology of reproductive organs of bovine freemartins.

A retrospective study of 217 cases of bovine freemartinism was made. Of these, 14 cases were diagnosed clinically, 141 were karyotyped and 62 were subjected to macroscopical examination of the reproductive tract. Of the 62 cases, 43 were assessed by measuring the reproductive organs (size and/or weight) and 41 were examined microscopically. Complete information on gross, histopathological and karyotyping analysis was available for only 10 animals. Freemartins showed reduced measurements of all reproductive organs. The mean lengths of vulva and vagina were 6.4 cm and 8.1 cm, respectively. Vesicular glands were observed in 30 freemartins. Histologically, these glands had more fibrous and less glandular tissue than the normal male vesicular glands. Uterine changes were variable, ranging from aplasia (two animals) to normal. Likewise, endometrial glands ranged from hypoplastic (decreased number and size) to normal. Glandular and myometrial cells showed prominent nuclei and less than normal cytoplasm, indicating a non-functional status. Gonadal size was reduced and an epididymis was present in seven animals. Rete ovarii were prominent and frequently occupied two-thirds of the gonad. Undifferentiated sex cords and abundant interstitial cells were salient features of the freemartin gonad. Oocytes were not observed. Ovarian follicles were seen in six cases. Karyotypic analyses demonstrated XY chimaerism in all freemartins.

Animals↗
PubMed1994

Immunopotentiation and delivery systems for antigens for single-step immunization: recent trends and progress.

The use of adjuvants for immunopotentiation has been investigated since the 1920s and a number of comprehensive reviews and monographs have been published on this subject. A recent trend in immunopotentiation has been the use of delivery systems which allow for sustained or controlled release of antigens and which induce prolonged immunity following a single dose. This concept has been termed either single-step or single-shot immunization. The delivery system has been modulated to potentiate the immune response either by delivering the antigen (and perhaps an adjuvant or adjuvants) either over a prolonged period of time or in a predetermined sequence or by incorporating substances with immunoadjuvant properties (e.g., lecithin and certain biodegradable polymers) as carriers within the delivery system. This Review focuses on the progress made in the design of delivery systems for immunopotentiation. Particular emphasis is given to delivery systems designed to achieve single-step immunization.

Adjuvants, Immunologic↗
PubMed1994

Effects of concurrent oral administration of lead, selenium or monensin on hepatic porphyrin levels in broiler chickens during sub-acute toxicosis.

Liver-porphyrin levels were found to have increased during sub-acute lead toxicosis. The presence of selenium or monensin in the diet of lead-intoxicated birds resulted in a further increase of liver-porphyrin levels. The results of this study indicate the presence of an interaction between lead and selenium or monensin in producing an increase in porphyrins in the liver tissue of broiler chickens.

Animals↗
PubMed1994

Pathomorphological studies in European bison (Bison bonasus Linnaeus, 1758) with seropositive reaction to Coxiella burnetii.

Comprehensive serological and histopathological examinations of 47 free living European bison (Bison bonasus Linnaeus, 1758) were performed. Of these animals, 36 were serologically positive due to Coxiella burnetii, which confirmed the presence of Q fever epizootic foci in this population of wild animals in Poland. The presence of multiple foci of mononuclear cells typical for Q fever was a consistent finding in all tissues of the majority of C. burnetii seropositive animals under study. Pathomorphological changes observed in myocardium as the focal coagulation necrosis, and in kidneys, resembled the glomerular lesion observed in humans with Q fever, as well as in the experimental Q-fever infections in laboratory animals. These changes were absent in bison showing a C. burnetii seronegative reaction.

Animals↗
PubMed1994

Oral administration of monensin and lead to broiler chicks: effects on haematological and biochemical parameters.

Monensin and lead were administered separately or concurrently at different toxic doses to broiler chicks. Administration of lead alone did not result in a significant depression of haematological parameters. Administration of higher levels of monensin caused a reduction in haematocrit and an increase in blood serum levels of alanine aminotransferase, aspartate aminotransferase and cholesterol. Concurrent administration of monensin and lead caused a severe depression of haematological profiles which indicated the existence of an interaction between the two substances. It was concluded that concurrent administration of monensin and lead potentiated the toxic effects of each other.

Administration, Oral↗
PubMed1993

Induction of phenotypic changes in SCLC cell lines in vitro by hexamethylene bisacetamide, sodium butyrate, and cyclic AMP.

BACKGROUND: Hexamethylene bisacetamide (HMBA), sodium butyrate (NaBt), and cyclic AMP (cAMP) have been shown to induce differentiation, which may regulate tumour growth differently from conventional cytotoxic drugs. It was the intention in the present study to determine whether alterations could be induced in the phenotype of small cell lung cancer (SCLC) cell lines with HMBA, NaBt and cAMP, and whether these alterations would correlate with reduced growth in vivo, implying a phenotypic shift from malignancy towards differentiation. MATERIALS AND METHODS: The cell lines were NCI-H69, H187 and H128. The activity of dopa decarboxylase (DDC), the BB isozyme of creatine kinase (CK-BB), the synthesis of bombesin-like peptide (BLI), and the presence of neurone specific enolase (NSE) and chromogranin were used as markers of the small cell phenotype. Clonogenicity in suspension in agar, and growth as xenografts in nude mice, were used as malignancy-associated properties. Cell proliferation in vitro was determined by cell counting and growth curve analysis. RESULTS: HMBA, NaBt and cAMP were found to be reversibly cytostatic in liquid culture and pre-exposure reduced the cloning efficiency in agar by 60%-80%. Growth as xenografts was inhibited (three- to five-fold increase in the tumour doubling time), most significantly by NaBt. Effects of phenotypic markers were more complex. The most significant were a two-fold reduction in DDC with NaBt and HMBA, a 50% increase in CK-BB with cAMP, and a 70%-100% increase in secreted BLI with HMBA and cAMP, in NCI-H69 cells. No significant effects were seen on NSE and chromogranin. There was little sign of an interaction with adriamycin and vincristine, although a slight increase was observed in the ID50 of VP-16 following treatment with cAMP. CONCLUSIONS: NaBt, HMBA and cAMP were cytostatic and inhibited tumour growth, but there was no coordinated response in marker expression that would confirm phenotypic alteration indicative of differentiation. The problem of defining differentiation in SCLC further complicated the analysis. The possibility remains of combining these agents with conventional cytotoxics as there appears to be little antagonistic effect, and other studies have suggested synergism may be possible with correct scheduling.

Acetamides↗
PubMed1993

Effects of concurrent oral administration of toxic levels of monensin and lead on concentration of different elements in the liver of broiler chicks.

Monensin and lead, separately or concurrently, were orally administered to broiler chicks at different toxic levels. Monensin slightly increased the selenium and profoundly increased the lead and iron levels of liver. Lead also increased the level of iron in liver. Levels of lead and iron in liver tissue further increased when monensin and lead were administered concurrently. An increased mortality was recorded due to concurrent administration of monensin and lead during acute toxicosis but during subacute toxicosis body weights were higher in birds administered monensin and lead concurrently than those given these substances separately.

Administration, Oral↗
PubMed1993

Effects of concurrent oral administration of monensin and selenium on some haematological and biochemical parameters in broiler chickens.

Monensin and selenium (sodium selenite) at different toxic levels were administered orally to the broiler chickens for variable periods. A depression in haematological parameters and biochemical ones such as alanine and aspartate aminotransferase, serum total protein and cholesterol were recorded in acute and subacute toxicosis of these substances. The present experiments led to the conclusion that concurrent administration of selenium and monensin at toxic levels resulted in exasperated toxic response in broiler chickens which in turn had been produced by embellishment of toxicosis inducing properties of both examined substances.

Administration, Oral↗
PubMed1993

Concurrent oral administration of monensin and selenium to broiler chickens: effects on concentration of different elements in the liver.

Broiler chicks were kept on feeds amended by the addition of 240 mg monensin and 15 mg selenium with or without 200 mg vitamin E/kg. After 12 days, birds in different groups were orally administered three doses of 250 mg monensin and 5 mg selenium/kg body weight. In the second experiment, after four weeks of adaptation on amended feeds, similar groups were orally administered 40 mg monensin and 1 mg selenium/kg body weight on alternate days for four weeks. Monensin increased the liver iron level. Selenium increased the hepatic levels of selenium and iron while variable degrees of depression occurred in copper, zinc, manganese and magnesium levels. Concurrent administration of monensin and selenium significantly increased the liver selenium levels. A marked decrease in body weight and increased mortality were recorded due to concurrent administration of monensin and selenium.

Administration, Oral↗
PubMed1993

Effects of concurrent administration of lead and selenium on some haematological and biochemical parameters of broiler chickens.

As compared to intoxication with lead or selenium alone, the concurrent administration of lead and selenium to broiler chickens produced more deleterious effects characterized by adverse changes in haematological parameters and severe alterations in serum total protein, aspartate aminotransferase (AST), cholesterol and alkaline phosphatase levels. Deleterious effects were more pronounced when lead was administered as second toxic chemical in the presence of selenium in the diet of the birds. Significant haematological depressions leading to anaemia were recorded during subacute lead toxicosis when selenium was concurrently administered in the feed, indicating an enhancement of lead toxicity in the presence of selenium.

Animals↗
PubMed1992

A study of the phase transition behaviours of cholesterol and saturated egg lecithin, and their interaction by differential scanning calorimetry.

The thermal behaviours of hydrogenated egg lecithin (PC) and cholesterol (C) in anhydrous form and in aqueous dispersions were studied by differential scanning calorimetry. The role of C in phase transitions of C-PC mixtures prepared by physical mixing or coprecipitating from chloroform has been examined. C underwent a phase transition at 34 degrees C and a second one at 76-78 degrees C which depended on the thermal history of the samples. C lowered the gel to liquid crystalline phase transition temperature (Tt) of the aqueous dispersions prepared from C-PC coprecipitates, broadened the endothermic peak at the Tt, and at 1:1 molar ratio the C-PC system did not undergo the phase transition. The C-PC interaction was observed below the Tt. In aqueous dispersions prepared from C-PC physical mixtures, C did not influence the phase transition and acted like an inert diluent. Pellets prepared from C-PC mixtures formed myelin bodies as a result of their erosion in 0.185 M borate buffer (pH 7.4) at below Tt, but the thermal behaviours of these myelin bodies were different for pellets prepared differently. Addition of bovine serum albumin (BSA) (10%, w/w) to the physical mixtures or coprecipitates of C-PC, or to PC alone did not show any effect on the thermal behaviours of their aqueous dispersions at the Tt.

Buffers↗
PubMed1992

Bronchial carcinoid tumor: experience over 20 years.

Nineteen cases of bronchial carcinoid tumor seen over 20 years in a 1,000-bed, tertiary medical center were retrospectively reviewed. They consisted of 0.4 per cent of all patients with lung tumors. Initial complaints were hemoptysis, persistent pulmonary infection, chest pain, and diarrhea. Two of the five patients with atypical carcinoid tumors came to the hospital with diarrhea as a result of their chemically active tumors. However, seven patients (36%) were asymptomatic and were diagnosed after an abnormal chest radiograph was noted incidentally. Of 13 patients receiving bronchoscopic examination, 9 (69%) had visible tumors. Bronchial biopsy was performed in 7 patients and led to a diagnosis in all seven. Significant bleeding was noted in 3 patients as a result of biopsy. Lobectomy was the most common surgical procedure in this series. Follow-up of these patients was from 6 months to 15 years. The general outcome for patients with typical carcinoid was good. However, all patients with atypical carcinoid died as a result of dissemination.

Academic Medical Centers↗
PubMed1992

The effect of transfection with the oncogenes H-ras and c-myc on the radiosensitivity of a mink epithelial cell line.

We have investigated the effect of transfection with the oncogenes c-myc and H-ras on cellular radiosensitivity. We obtained a mink lung epithelial line, Mv1Lu (ATCC CCL-64), and two sublines which had been transformed by transfection with c-myc and mutated (T24) H-ras 1. The cell survival parameters do not differ significantly between the three lines. These parameters were, for the parent line: D0 = 1.95 Gy, n = 2.0; for the c-myc transfected line: D0 = 2.10 Gy, n = 2.33; and for the H-ras transfected line: D0 = 2.40 Gy, n = 1.77. Although the terminal slope of the survival curve of the cells of the parent line is slightly steeper than that for the cells of either of the transfected lines, the differences are not significant. Nor is there any difference between the cell lines at the clinically relevant dose of 2 Gy. We conclude that neither activated H-ras nor c-myc oncogenes alter the radiosensitivity of the Mv1Lu line.

Animals↗
PubMed1992

Brachiocephalic revascularization: a comparison between carotid-subclavian artery bypass and axilloaxillary artery bypass.

Sixty-seven patients who underwent carotid-subclavian bypass (CSBP) (28 CSBPs only and eight with carotid endarterectomy) or axilloaxillary artery bypass (n = 31) with polytetrafluoroethylene grafts were followed up for a mean of 69.2 and 71.9 months, respectively. Indications for surgery in the CSBP group included hemispheric transient ischemic attack (TIA)/cerebrovascular accident in five, nonhemispheric TIA in seven, upper extremity ischemia in 15, and combined TIA and arm ischemia in nine patients. In the axilloaxillary artery group, two patients had hemispheric TIA, five had nonhemispheric TIA, 12 had upper extremity ischemia, and 12 had combined TIA and arm ischemia. Graft patency was determined clinically and confirmed by segmental Doppler pressures, duplex ultrasonography, or angiography. The 30-day mortality rate was approximately 3% in both groups. The 30-day complication rate was 3% for the axilloaxillary artery group and 8% for the CSBP group (not statistically significant). Relief of symptoms was achieved in 100% of patients in both groups; however, 20% of the patients in the axilloaxillary artery group had a recurrence of symptoms, in contrast to 5.6% in the CSBP group. The cumulative 10-year primary and secondary patency rates, calculated by life-table analysis, were 66% and 84.6% for the axilloaxillary artery procedures and 93.8% and 93.8% for the CSBP procedures, respectively (statistically significant). Concomitant carotid endarterectomy with CSBP did not influence graft patency. In conclusion, both bypasses have comparable morbidity and mortality rates; however, the CSBP has a statistically significantly better primary patency rate than the axilloaxillary artery bypass. Therefore CSBP should be the procedure of choice and the axilloaxillary artery bypass should be restricted to high-risk patients.

Arterial Occlusive Diseases↗
PubMed1991

Conventional versus thrombolytic therapy in spontaneous (effort) axillary-subclavian vein thrombosis.

Effort axillary-subclavian vein thrombosis in young patients has produced long-term disability because of the failure of the thrombosed vein to recanalize. Ten consecutive patients treated in our institution were analyzed. All patients were diagnosed by venography. Four patients received thrombolytic therapy. Three of these had complete resolution and one had partial resolution of the symptoms and thrombus, that was confirmed by venography and duplex imaging. The remaining six patients were treated with conventional anticoagulant therapy. Three of these patients had no resolution, one had complete resolution of both symptoms and thrombus, and two had only partial resolution of symptoms but no resolution of thrombus. Thrombolytic therapy appears to be superior to anticoagulation in the dissolution of symptoms in effort vein thrombosis and should be considered in its management if the diagnosis is made early.

Adult↗
PubMed1990

Role of thrombolytic therapy in axillary-subclavian vein thrombosis.

Axillary-subclavian vein thrombosis in young patients has produced long-term disability because of failure of the thrombosed vein to recanalize. In a review of 10 patients with axillary-subclavian vein thrombosis treated in our institution, four were effort vein thrombosis. All patients were diagnosed by venography. One patient received urokinase with complete resolution of symptoms and complete dissolution of the clot after two days of initial therapy, which was confirmed by venography and duplex imaging. Another patient received streptokinase with partial resolution of symptoms and dissolution of the clot, which was confirmed by venography. The other two patients were treated with conventional anticoagulant therapy with partial resolution of symptoms and no dissolution of the clot. Thrombolytic therapy appears to be superior to anticoagulation in dissolution of symptoms in effort vein thrombosis and should be considered in its management if the diagnosis is made early.

Adult↗