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Biomedical subjects

F Mahmood

Publications and source records attributed to F Mahmood.

At least 37 records · Page 2Linked to original sources
PubMed1995

Feeding the mosquito Aedes aegypti with TMOF and its analogs; effect on trypsin biosynthesis and egg development.

Female Aedes aegypti that were given a blood meal by enema deposited yolk in their oocytes and synthesized trypsinlike enzymes in their midgut. When females were given an enema of Aea-TMOF (Trypsin Modulating Oostatic Factor) (NH2-YDPAPPPPPP-COOH) and blood both egg development and trypsin biosynthesis were inhibited. Similar results were observed if TMOF was mixed with the blood meal and fed to female mosquitoes through a membrane. Renin inhibitor (NH2-PHPFHFFVYK-COOH) or poly proline given by enema with the blood meal did not affect egg development or trypsin biosynthesis. Feeding of TMOF analogs P1 (NH2-YDPAP-COOH) or P4 (NH2-YDPAPPPP-COOH) inhibited trypsin biosynthesis in the midgut. Injecting or giving an enema of an amidated peptide (NH2-WRPGPPPPPP-CONH2) of HIV-2 X-ORF protein also inhibited egg development and trypsin biosynthesis in the mosquito gut. When [3H]TMOF was purified by high performance liquid chromatography (HPLC) and fed with the blood meal through a membrane to female mosquitoes, [3H]TMOF outside the gut increased linearly for the first 24 h and 28% of the hormone was found outside the gut at 72 h. These results suggest that TMOF and its active analogs traverse the gut epithelial cells into the hemolymph, bind TMOF gut receptor(s) and modulate trypsin biosynthesis.

Aedes↗
PubMed1994

Anopheles culicifacies: effects of age on the male reproductive system and mating ability of virgin adult mosquitoes.

Under controlled laboratory conditions of 28-30 degrees C and 16:8 L:D photoperiod, an attempt was made to develop an age-grading technique for Anopheles culicifacies males. Mating activity was maximal when females were 5-12 days old males were 5-7 days old. The numbers of total and mature spermatocysts declined significantly with age, and the proportion of the testes occupied by the sperm reservoir increased as virgin males grew older. Mating resulted in the loss of spermatozoa and accessory gland substance from the reproductive system. Loss of mating ability of older virgin males seemed to be age-related, because the reproductive system contained ample supplies of accessory gland substance and spermatozoa. Morphological changes of the reproductive system, due to mating and age, were used to infer the age and reproductive history of unknown males in a laboratory evaluation.

Aging↗
PubMed1993

Biosynthesis of serine proteases in Lutzomyia anthophora (Diptera: Psychodidae).

Changes in the biosynthesis of serine proteases in adult Lutzomyia anthophora Addis were followed and compared with the larval and pupal stages. More chymotrypsinlike than trypsinlike enzyme was synthesized by 2-d-old and 3-d-old sugar-fed females and females that were fed blood 72 h earlier. A small increase in the amount of chymotrypsinlike enzyme occurred within the first 48 h after blood feeding, whereas trypsinlike enzyme activity increased rapidly after the blood meal and peaked at 72 h. [1,3-3H]DIP trypsinlike and chymotrypsinlike derivatives of sugar-fed and blood-fed females were compared using polyacrylamide gel electrophoresis.

Animals↗
PubMed1993

Dual inhibition of platelet-activating factor and arachidonic acid metabolism by ajmaline and effect on carrageenan-induced rat paw oedema.

The effects of ajmaline on human platelet aggregation, arachidonate metabolism and platelet activating factor (PAF)-induced lethality in rabbits were examined. Platelet aggregation induced by several stimuli (ADP, collagen, and PAF) was inhibited by increasing concentrations of ajmaline. The potency of ajmaline was higher when PAF was employed as stimulating agent in comparison with other agonists (IC50 70, 270 and 380 microM for PAF, ADP and collagen, respectively) whereas ajmaline had no effect against arachidonic acid-induced aggregation. In contrast however, ajmaline inhibited arachidonate metabolism by platelet homogenates. The formation of both thromboxane A2 and 12-hydroxy-eicosatetraenoic acid was inhibited by ajmaline with comparable potencies. Pretreatment of rabbits with ajmaline (50 mg kg-1) completely abolished the lethal effects of PAF (11 micrograms kg-1) given intravenously (P < 0.001). In addition, ajmaline at doses ranging from 50 to 100 mg kg-1 inhibited carrageenan-induced rat paw oedema (P < 0.001). In this test ajmaline was three times more potent than aspirin. In the light of these results we conclude that ajmaline, a known anti-arrhythmic agent is a PAF antagonist and a dual inhibitor of platelet cyclo-oxygenase and lipoxygenase enzymes with anti-inflammatory properties.

Ajmaline↗
PubMed1992

Biosynthesis of trypsinlike and chymotrypsinlike enzymes in immature Lutzomyia anthophora (Diptera: Psychodidae).

The biosynthesis of trypsinlike and chymotrypsinlike enzymes was followed in the four instars and pupa of Lutzomyia anthophora Addis. A 32-fold increase in the biosynthesis of trypsinlike enzymes was observed from the first to the fourth instar. Trypsinlike and chymotrypsinlike isozymes were also synthesized by pupae 1-8 d old. Similarly, a 29-fold increase in the biosynthesis of chymotrypsinlike isozymes also was observed from first to fourth instars. Several different [1,3-3H]DIP trypsinlike and chymotrypsinlike derivatives of first to fourth instars and pupae (1 and 8 d old) were studied using polyacrylamide gel electrophoresis and fluorography.

Animals↗
PubMed1992

Biosynthesis and metabolism of juvenile hormone III from methyl farnesoate by exposed corpora allata of Lutzomyia anthophora.

The in-vitro biosynthesis of [12-3H] juvenile hormone (JH) III by exposed corpora allata (CA) of teneral, sugar-fed, and blood-fed female Lutzomyia anthophora (Addis) was followed by incubating the CA for 4 h with [12-3H]methyl farnesoate. Synthesis of [12-3H]H III was determined by C18 reversed-phase high-pressure liquid chromatography (HPLC) and preparative gas chromatography. The rate of synthesis of JH III by teneral females was 5.6 fmol/h per CA. The CA of 1-d-old females synthesized 17 fmol/h per CA, whereas 3-d-old females synthesized 5.4 fmol/h per CA. The rate of synthesis of JH III 4 h after the blood meal increased to 17.3 fmol/h per CA and then declined to reach a minimum of 1.6 fmol/h per CA at 30 h before increasing again to reach 21.6 fmol/h per CA at 96 h. The concentration of methyl farnesoate in the tissue culture medium during incubation of CA from sugar- and blood-fed females was compared with the rate of synthesis of JH III and its metabolites diol-acid, diol, acid, and bisepoxide. The rate of synthesis of JH III and its metabolites from methyl farnesoate indicated a steady-state equilibrium of synthesis and metabolism of JH III by the exposed CA. The rapid increase in JH III synthesis immediately after the blood meal confirmed that in sand flies, like mosquitoes, there is an increase in the rate of synthesis of JH III immediately after the female takes blood. The role of the hormone in vitellogenin biosynthesis is also discussed.

Animals↗
PubMed1991

Effect of ivermectin on the ovarian development of Aedes aegypti (Diptera: Culicidae).

The effect of ivermectin (0.1 microgram/ml) on blood digestion, ovarian development, and ovipositional attributes of Aedes aegypti was studied using standard morphological and histological techniques. Uncoordinated movements and paralysis were observed in most ivermectin-treated females within 1 h after ingestion of blood containing the chemical. Eight days after the blood meal, 23.5% of the treated females had died, whereas no mortality occurred in controls. Formation of the peritrophic membrane and digestion of the blood meal were delayed in the surviving treated mosquitoes. The most striking effect of ivermectin on Ae. aegypti at this dosage was on ovarian development. Changes observed among ivermectin-treated mosquitoes included: blood digestion without development of ovarian follicles; degeneration of primary follicles and formation of ovarian dilatations within 24 h after ingestion of the chemical; significant reduction in the rate of vitellogenesis and follicle development; decreased egg production; reduced egg hatching; abnormal egg size and shape; and increased percentages of unhatched embryonated and sterile eggs. Although the precise action of ivermectin on Ae. aegypti is unknown, our studies indicate that the chemical directly or indirectly affects at least three major organ systems (nervous, digestive, and reproductive).

Aedes↗
PubMed1991

Inhibition of platelet activating factor by ajmaline in platelets: in vitro and in vivo studies.

The in vitro and in vivo effects of ajmaline and its derivatives on platelet aggregation and platelet-activating factor (PAF) induced death in rabbits was studied. Ajmalinc and acetyl ajmaline selectively inhibited PAF-induced aggregation in a concentration related manner. Weak or no inhibition of aggregation was observed when ADP, collagen or arachidonic acid were used as aggregating agents. Similarly ajmaline or acetyl ajmaline also inhibited the lethal effects of PAF in the rabbit. PAF (8-11 microg/kg i.v.) caused sudden death in rabbits due to platelet aggregation and cardiac failure. Pretreatment of rabbits with ajmaline (50 mg/kg i.p.) protected conscious rabbits from PAF (11 microg/kg i.v.)-induced death. Since PAF is a powerful inducer of platelet aggregation via stimulation of specific PAF membrane receptors, our data is suggestive that ajmaline (an anti-arrhythmic agent) could emerge as a new class of PAF antagonists.

Journal Article↗
PubMed1989

The Muir-Torre syndrome: a disease of sebaceous and colonic neoplasms.

The Muir-Torre syndrome of sebaceous neoplasms of the skin, with or without keratoacanthomas, and multiple low-grade visceral malignancies with prolonged survival is a rare disorder. Colonic polyps are frequently present, and the syndrome appears to be familial. We report 2 unrelated patients with the Muir-Torre syndrome. Each case exhibited sebaceous adenomas. Gastrointestinal findings included colonic adenocarcinomas and a tubulovillous adenoma. Although an unusual disease, the Muir-Torre syndrome requires recognition because these patients are at risk for multiple primary malignancies and may have family members also at risk.

Adenocarcinoma↗
PubMed1988

Absence of teratogenic effects of progesterone on the developing genital tract of the human female fetus.

It has been questioned whether prenatal exposure to progesterone, like exposure to diethylstilbestrol (DES), results in teratogenic abnormalities of the upper and lower genital tract in human females. Through the use of a recently described model in which human fetal reproductive tracts can be transplanted and grown in vivo for extended periods in athymic nude mice, genital tracts from human female fetuses, ages 7 to 18 weeks postovulation, were grafted into castrated murine hosts and grown for 4 to 10 weeks in the presence or absence of continuous exposure to progesterone. Substantial growth was observed. For all specimens, the morphogenetic process proceeded normally, resulting in the harmonious organization of a complete, well differentiated genital tract composed of fallopian tubes, uterine corpus, and cervix and vagina. The fallopian tubes were highly convoluted and disclosed fimbria. The uterine corpus was lined by a simple columnar epithelium; two layers of stroma in the wall were distinctly separated from each other. In the older specimens, the outer layer of stroma had assumed microscopic properties diagnostic of smooth muscle (myometrium). In the majority of specimens the region of the cervix/vagina disclosed the development of a fornix-like evagination at which point or slightly cranially there was a gradual but defined transition from columnar epithelium to squamous epithelium. The inner layer of endometrial stroma tapered and disappeared at or close to the squamocolumnar junction. The vaginal stroma was a single homogeneous layer and was continuous with the myometrium of the uterine corpus. In the context of this model system, prenatal exposure of the developing human female genital tract of progesterone was not associated with any obvious teratogenic effects.

Animals↗
PubMed1986

Population dynamics of some Pakistan mosquitoes: temporal changes in reproductive status, age structure and survivorship of Anopheles culicifacies, An. stephensi and Culex tritaeniorhynchus.

The reproductive biology and age-structure of female Anopheles culicifacies, An. stephensi and Culex tritaeniorhynchus were studied at rural Punjabi villages near Lahore, Pakistan, during 1976-1980. Both Anopheles remained gonotrophically active throughout the year with blood-fed, gravid, parous and virgin females collected during all months. Culex tritaeniorhynchus populations bifurcated into reproductively active, non-overwintering and reproductively inactive, overwintering populations in October and/or November. Most female Cx. tritaeniorhynchus overwintered as inseminated nullipars with ovaries arrested at follicular State I; however, host-seeking and parous females were collected during every month of the year. Survivorship was calculated for each species by three methods and was negatively correlated with mean monthly ambient temperature. The ovarian tracheolation method provided inadequate estimates of parity for females collected at diurnal resting sites which refed the night of oviposition, but was suitable for Cx. tritaeniorhynchus females captured at bovid baits. The dilatation method of Polovodova was applied to all three species and yielded survivorship patterns which were constant with age and agreed well with a log-linear model. Anopheles culicifacies survived longer than did An. stephensi and thus was considered a better vector of malaria. Age-specific survivorship tables were constructed for all three species for those periods of the year when the gonotrophic rhythm was constant and generations were overlapping.

Animals↗
PubMed1985

An ovarian chromosome map of Anopheles stephensi.

A polytene chromosome map of Anopheles stephensi has been prepared from the ovarian nurse cells of adult females. Many homologous regions can be recognized in comparisons between the ovarian and salivary gland chromosome maps but band for band homologies are not readily evident. The preparation of polytene chromosomes from ovarian nurse cells is easier than from the larval salivary glands and the results more consistent.

Animals↗
PubMed1984

Vector incrimination studies and observations on species A and B of the taxon Anopheles culicifacies in Pakistan.

Studies on anopheline mosquitoes in selected villages of Punjab Province, Pakistan have incriminated Anopheles culicifacies species A as the primary malaria vector. Although An. stephensi and An. subpictus showed higher immediate gut infection rates, estimations of relative abundance, age structure and survivorship, and observations of late gut and salivary gland infection rates suggested that neither species was a major vector in these villages. A survey of An. culicifacies populations detected the presence of both species A and B in several localities in Pakistan. Laboratory investigations demonstrated that both species are capable of supporting the extrinsic cycle of Plasmodium vivax. No recombination was observed between X-linked loci in species A/species B hybrid females; however, recombination was observed between loci in chromosome 2. Allelic tests between the X-linked white eye locus in species A and an X-linked white eye mutant in species B showed that the two loci are not allelic.

Alleles↗
PubMed1984

Inversion polymorphisms in natural populations of Anopheles stephensi.

A preliminary survey of natural populations of Anopheles stephensi Liston in Pakistan has uncovered the presence of 16 autosomal paracentric inversions. Twelve previously undescribed inversions were observed in the field populations and an additional new one was seen in a laboratory colony. A comparison of urban and rural populations showed striking differences in the kinds and frequencies of paracentric inversions.

Animals↗