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Biomedical subjects

F Mahmood

Publications and source records attributed to F Mahmood.

At least 19 recordsLinked to original sources
PubMed2005

Ruptured abdominal aortic aneurysm presenting as buttock pain.

This is the first case report of a ruptured aortic aneurysm presenting with acute right buttock pain. The patient was an 80 year old man. A literature search revealed one report of ruptured internal iliac artery aneurysm presenting with acute hip pain and another of an unruptured aortic aneurysm presenting with chronic hip pain. Thus the present case is another unusual presentation of ruptured abdominal aortic aneurysm and highlights the importance of careful history taking and clinical examination. A high index of clinical suspicion of aneurysm rupture should be maintained in elderly patients presenting with a history of collapse.

Aged↗
PubMed2005

Pathological effects of formalin (37% formaldehyde) feeding in female Japanese quails (Coturnix coturnix japonica).

The aim of this study was to determine the pathological effects of formalin on female quails. Seventy-five 1-day-old female Japanese quails (Coturnix coturnix japonina) were divided into five equal groups (A-E) and fed formalin daily at dose levels of 20, 10, 5, 2.5 and 0 mL/ kg feed, respectively. All birds were slaughtered at the end of the experiment -- the eighth week. No clinical signs were observed in quails fed 2.5 mL formalin/kg feed. Depression, dullness and anorexia were prominent in quails fed 20 mL formalin/kg feed. Feed intake, body weight, egg production and egg weight together with absolute and relative weight of organs, erythrocyte and leukocyte counts, hemoglobin concentration and hematocrit were decreased at higher doses, i.e., 10 and 20 mL formalin/kg feed. Total serum proteins and globulin significantly increased (P <0.05) in all formalin fed quails compared to control birds. No gross lesions were observed in the 2.5 mL formalin/kg fed group. At higher doses (10 and 20 mL formalin/kg feed) hemorrhages on the thigh muscles, decreased weight and reduction in area and folds of different segments of oviduct were recorded. Reduced size of liver, heart and kidneys was recorded in quails fed 20mL formalin/kg feed compared to controls and other birds. The histopathological changes in oviduct consisted of degeneration of mucosal glands characterized by vacuolation of nuclei of cells. It was concluded from the study that formalin feeding to female quails at 2.5 mL/kg feed is without harmful effects, however, higher doses are not without health risks.

Animals↗
PubMed2003

Pathological effects of formalin (37% formaldehyde) mixed in feed or administered into the crops of White Leghorn cockerels.

This study compared the adverse effects of formalin administered by two different methods. Formalin mixed with the feed (2.5, 5.0 and 10 ml/kg) was given to 10-week-old White Leghorn cockerels for a period of 8 weeks. Simultaneously in other groups, a 3% solution of formalin was administered into the crops (5, 10, 15 and 20 ml/bird/day). Total amount of formalin utilized during the experiment in the feed of individual bird of groups given 2.5, 5 and 10 ml/kg was 6.25, 3.9 and 1.6% higher than those administered 5, 10 and 20 ml of 3% formalin into crop, respectively. Body mass and feed intake in all feed-mixed groups and those given 5 and 10 ml formalin (3%) into the crop were not significantly different from control. Administration of 15 and 20 ml formalin (3%) into crop resulted in depression, delayed onset of crowing, significantly decreased feed intake, lower body mass, decreased mass and volume of testes, ulceration in crops, sloughing of mucosa and petechial haemorrhages in proventriculus. All the groups given formalin had significantly smaller diameters of seminiferous tubules. Kidneys of the birds administered formalin into crop exhibited pyknotic nuclei of epithelial cells in proximal tubules. Non-significant differences in different parameters and lesser degree of pathological changes in birds given formalin-mixed feed than their corresponding crop-administered groups suggested that formalin present in the feed had partially evaporated. Therefore, birds ingested less amount of formalin than that originally mixed in the feed.

Administration, Oral↗
PubMed2003

Previous infection protects house finches from re-infection with St. Louis encephalitis virus.

Antibody titers against St. Louis encephalitis virus (SLE) measured by a plaque reduction neutralization test (PRNT) decreased rapidly in house finches (Capodacus mexicanus) after initial infection, whereas antibodies measured by enzyme immunoassay (EIA) remained detectable in all birds for the length of the experiment, indicating long-term persistence and greater assay sensitivity of the EIA. After 52 wk, birds were challenged by subcutaneous inoculation with the same strain of SLE virus. Virus was not detected for 1-4 d postchallenge in blood samples tested by plaque assay and RT-PCR or by xenodiagnosis in Culex tarsalis fed concurrently and then held for 11 d at 26 degrees C. Virus was detected by all three methods in control birds infected concurrently for the first time. Challenge with SLE produced a rapid and marked ananmestic rise in both neutralizing and EIA antibody titers that exceeded the primary response in the same birds or in concurrently inoculated control birds. At necropsy 4 wk postchallenge, 3 of 7 challenged and 1 of 2 positive control birds were chronically infected, with viral RNA detected by RT-PCR in brain, spleen, lung, and/or kidney tissues. Our results indicated that persistence of protective antibody prevents reinfection during the following season and may prevent the recrudescence of infectious virus in chronically infected birds.

Animals↗
PubMed2001

Altered myosin light-chain phosphorylation in resting platelets from premenopausal women with diabetes.

Gender-related differences in the rate of coronary heart disease (CHD) between premenopausal women and men are greatly diminished in women with diabetes mellitus (DM). This may be related, in part, to altered platelet function in premenopausal diabetic women. Hyperglycemia may contribute to increase platelet aggregation through enhancement of oxidative stress, increased nitric oxide (NO) destruction, and increased myosin light-chain (MLC) phosphorylation (MLC-P). Accordingly, we investigated functional and biochemical parameters of platelet function in 32 women (14 premenopausal and postmenopausal controls and 18 age-matched patients with DM); platelet MLC-P and cyclic guanosine monophosphate ([cGMP] reflecting NO) were assessed. Other parameters including age, body mass index (BMI), waist to hip ratio, total cholesterol, and platelet count were not different in the control and diabetic groups. In the premenopausal women, baseline MLC-P was lower in women with DM versus the control group (P = .02). GMP levels were similar in the two groups at baseline (22.7 +/- 3 fmol/mL in controls v 23.1 +/- 3 fmol/mL in diabetic subjects) and 3 minutes after insulin exposure. The platelet content of ascorbic acid (AA), an endogenous antioxidant compound, was elevated in premenopausal women with DM (P = .02) compared with the controls. Despite similar estradiol (beta,E2) levels, platelets of premenopausal women with DM exhibited reduced MLC-P. This paradoxic difference may be accounted for by an increase in platelet AA, as this suggests decreased platelet oxidative stress in this patient population. These observations indicate that an altered redox state and associated MLC-P of platelets does not contribute to enhanced platelet aggregation and CHD in premenopausal women with DM.

Adolescent↗
PubMed2000

Susceptibility of geographically distinct Aedes aegypti L. from Florida to Dirofilaria immitis (Leidy) infection.

In the present study, five geographically distinct populations of Aedes aegypti L. from various regions of Florida were compared for their susceptibilities to Dirofilaria immitis (Leidy) infection. The populations were from Gainesville (North Central), Jacksonville (North Eastern), Naples (South Western), Sarasota (West Central), and Vero Beach (East Central). Mosquitoes of all the populations had fewer parasites in their Malpighian tubules 6 and 13 days after blood feeding compared to the number of microfilariae initially ingested. There was no significant difference in the mean number of the total parasites per female 6 and 13 days after taking an infectious blood meal. In comparison, significantly larger numbers of the microfilariae completed development in the laboratory-selected Vero Beach susceptible strain. Females excreted microfilariae within 72 hr. of engorgement on an infected dog and the Gainesville, Jacksonville, Naples, and Sarasota populations had 20-23% females that lacked ovarian development six days after blood feeding. Out of these, in 16-22% of the females from the Jacksonville, Naples, and Sarasota populations, parasite development was arrested mostly as moribund prelarvae and only few developing larvae were observed. All females of the Gainesville population that did not develop eggs (20%) also lacked parasites. In the Jacksonville population, 23% of the females that matured eggs had no infection. Eight percent of the females from the Sarasota population exhibited a similar response. Low survivorship was observed at 6 and 13 days after imbibing an infectious blood meal. Females showed melanization of microfilariae in the Malpighian tubules, on the midgut wall, and in the hemocoel. Cellular melanization response was observed in the hemocoel, whereas, a humoral melanization response was observed in the Malpighian tubules. The Vero Beach susceptible strain showed maximum vector efficiency and lowest survival at 13 days post-blood meal compared to the Jacksonville and the Gainesville populations.

Aedes↗
PubMed1999

Life history characteristics of Wyeomyia smithii from New Jersey.

We colonized Wyeomyia smithii (Coquillett) from southern New Jersey and studied life history characteristics in the laboratory. Males and females showed no significant difference in time spent from first to third instar, but female larvae remained in fourth instar 2.1 days longer than males. At 22 +/- 2 degrees C females emerged 22.6 +/- 3 days after egg hatch; males emerged approximately two days earlier. Male emergence peaked five hours after dawn; females showed a trend to emerge late in the day. Rotation of male terminalia was completed 9 to 11 hours after emergence. Females were capable of mating immediately after emergence. Wyeomyia smithii females laid their first egg batch four to six days after emergence. Females were capable of laying up to seven batches of eggs, however the mean number of eggs per oviposition decreased significantly as the number of oviposition cycles increased.

Animals↗
PubMed1998

Familial cerebellar hypoplasia and pancytopenia without chromosomal breakages.

Two siblings manifested a neuro-haematologic syndrome characterised by low birth weight, failure to thrive, chronic persistent tongue ulceration, severe truncal ataxia and pancytopenia without either telangiectasia or chromosomal instability. One sibling died from sepsis and the cerebellum demonstrated reduced cellularity of the molecular and granular layers with relative preservation of Purkinje cells and minimal gliosis. A surviving sibling has shown haematologic progression to a myelodysplastic disorder. There was no evidence of any chromosomal instability following exposure of fibroblasts and lymphocytes to irradiation. Monosomy-7 was not present in the surviving sibling. We suspect that these two patients represent another example of the rare Hoyeraal-Hreidarsson syndrome and we are currently engaged in very close monitoring of the surviving sibling for evidence of any karyotypic abnormality.

Ataxia↗
PubMed1998

Effect of temperature on the development of Culiseta melanura (Diptera: Culicidae) and its impact on the amplification of eastern equine encephalomyelitis virus in birds.

Eastern equine encephalomyelitis virus (EEE) is perpetuated in a maintenance cycle that involves Culiseta melanura (Coquillett) as the enzootic vector and passerine birds as the amplifying hosts. Amplification of virus in any given year requires an influx of nulliparous Cs. melanura in the presence of susceptible avian hosts. We conducted laboratory experiments at constant temperatures from 10 to 34 degrees C to develop thermal heat summation models to predict emergence in nature. Embryonic development progresses slowly at 10 degrees C, and the time to eclosion decreased significantly as temperatures increased to 28 degrees C. High temperature were lethal and eggs failed to hatch at 32 degrees C. The thermal minimum (t0) for embryonic development was 9.38 degrees C, and 38.46 degrees-days (DD) were required for egg hatch. The time for larval development decreased with increasing temperatures. Cs. melanura larvae develop in subterranean habitats (crypts) where water temperatures remain below 20 degrees C throughout the summer. Under controlled conditions, egg hatch to emergence took 8 mo at 10 degrees C, 3 mo at 16 degrees C, and 1 mo at 22 degrees C. The thermal minimum for larval development (t0) was 8.5 degrees C, and 467.29 DD were required from eclosion to adult emergence. Our findings indicate that Cs. melanura is well suited to develop in cold water crypts where the larvae are collected most frequently. The mosquito appears to be bivoltine in the northeast with an overwintering generation of larvae that emerges as a spring brood of adults and a summer generation of larvae that emerges in fall. Higher than normal water temperatures hasten development of the summer generation and increase the probability for amplification of EEE by bringing large numbers of nulliparous mosquitoes into contact with recrudescing virus for subsequent transfer to the growing population of susceptible juveniles. Water temperatures in the crypts also may regulate the northern limit for virus amplification each year.

Animals↗
PubMed1998

Ovarian development and parity determination in Culiseta melanura (Diptera: Culicidae).

A laboratory colony of Culiseta melanura (Coquillett) was used to follow ovarian development from emergence to oviposition and to validate the accuracy of using follicular dilatations to age grade females. We observed no change in the size of the primary follicles in unfed females from emergence to 3 d of age. Sugar feeding stimulated follicular growth and produced the following 3 types of ovarioles: (1) large primary follicles that eventually developed into functional ovarioles; (2) lesser numbers of small primary follicles that developed small amounts of yolk after blood feeding but degenerated in the latter stages of development; and (3) small primary follicles that did not develop yolk after blood feeding, exhibited accelerated growth, and became rogue ovarioles with multiple false dilatations. The yolk of the small primary follicles that degenerated after blood feeding was resorbed during stage IV of egg development, and the degenerating follicles resembled gonotrophic dilatations in the latter stages of the cycle. This process produced gravid females with some secondary follicles that appeared to possess a gonotrophic dilatation. Other authors have termed these artifacts false or agonotrophic dilatations. Degenerating ovarioles bearing these artifacts were used to determine physiological age in blood fed and gravid Cs. melanura. Nulliparous females in the latter stages of gonotrophic development have single false dilatations on degenerating ovarioles, 1-parous females have 2 false dilatations on degenerating ovarioles. In unfed, nulliparous females, false dilatations can be distinguished from true dilatations because they are attached to secondary follicles that are much smaller than the primary functional follicles that fill most of the ovary. In blood fed and gravid females, follicles that support false dilatations always lack yolk. Rogue ovarioles are unreliable indicators of physiological age and should not be used for diagnostic purposes.

Animals↗
PubMed1998

Laboratory bioassay to compare susceptibilities of Aedes aegypti and Anopheles albimanus to Bacillus thuringiensis var. israelensis as affected by their feeding rates.

This study presents the effect of differences in the feeding rates of Aedes aegypti and Anopheles albimanus on their susceptibilities to Bacillus thuringiensis israelensis. Aedes aegypti was more susceptible than An. albimanus because of its faster rate of feeding. Aedes aegypti ingested 11.5 times more spores than did An. albimanus, resulting in lower LT50 values. Anopheles albimanus larvae fed at a slower rate and required fewer spores than Ae. aegypti to induce 50% mortality. These findings support earlier reports of much higher concentrations of B. thuringiensis required to kill various anopheline species.

Aedes↗
PubMed1997

Age-related changes in development of the accessory glands of male Anopheles albimanus.

This study presents the effects of age on the accessory glands of male Anopheles albimanus. The paired oval glands have an outer muscular layer and an inner layer of columnar secretory cells. Male pupae have uniformly long columnar cells and contain only traces of male accessory gland substance (MAGS). In newly emerged males, the posterior section of the gland has short columnar cells that produce an opaque, white MAGS consisting of one type of secretory granules. The anterior section has long columnar cells that produce yellow as well as white MAGS. In 84-h-old males, the columnar cells are short throughout the gland and the glands are replete with both forms of MAGS. The amount of MAGS may control secretory activity of the columnar cells by a feedback mechanism.

Animals↗
PubMed1997

A thermal heat summation model to predict the duration of the gonotrophic cycle of Culiseta melanura in nature.

This study determined the effect of temperature on the gonotrophic cycle of Culiseta melanura and developed a thermal heat summation model to calculate its duration under field conditions. A colony of Cs. melanura was used from New Jersey (F13-F17 generation) and the length of the gonotrophic cycle was observed at 2, 10, 16, 22, 28, 32 and 34 degrees C. None of the mosquitos survived at 2 degrees C or 34 degrees C and none laid fertile eggs at 32 degrees C. A linear regression analysis on the data showed that the thermal minimum for ovarian development was 6.4 degrees C and 95.87 degree days were required above 6.4 degrees C to complete one gonotrophic cycle. A thermal heat summation model is presented to allow calculation of the duration of the gonotrophic cycle under field conditions when average temperatures are known.

Animals↗
PubMed1997

Larval competition in Aedes triseriatus (Diptera: Culicidae): effects of density on size, growth, sex ratio, and survival.

We assessed the effect of increased larval density on selected life table attributes of larval Aedes triseriatus. Larvae were reared at densities of 0.125, 0.250, and 0.375 larvae/cm3 of water. The parameters we evaluated included duration of each developmental instar, percent survival to adult emergence, sex ratio, and size of early and late emerging adults. The amount of time spent in the first and second instar was not affected by density, but crowding lengthened duration of later instars significantly. Males emerged earlier than females at all densities, and there was no difference in the ratio of males to females due to crowding. Crowding did increase the overall developmental time of both sexes and produced significantly smaller adults of both sexes. Densities of 0.375 larvae/cm3 resulted in a significant increase in mortality. Results suggest that the effects of crowding in container habitats should be allowed for in the construction of time-specific life tables where duration of larval instars is used in the calculations. The importance of smaller body size as a result of crowding in container habitats is discussed in terms of vector competence of Ae. triseriatus in the transmission of LaCrosse encephalitis virus.

Aedes↗
PubMed1997

Observations on multiple bloodfeeding in field-collected Culiseta melanura.

This study examined field populations of Culiseta melanura for evidence of partial blood meals and multiple feeding behavior. Engorged specimens that had 1/3 or less abdominal distention together with eggs in stage I-II of ovarian development were recorded as mosquitoes that had taken partial blood meals. Multiple blood meals were credited to engorged specimens with fresh blood as well as partially digested blood surrounded with separate peritrophic membranes and eggs in stage III or IV of ovarian development. Results indicated that only 17 of 532 Cs. melanura were captured with a partial meal, indicating that natural populations feed to repletion more than 95% of the time. Less than 1% of the specimens showed physical evidence of feeding on multiple hosts. Culiseta melanura appears to be highly efficient at obtaining a full blood meal and seems to be extremely reluctant to refeed once ovarian development has been initiated. As a result, multiple feeding does not appear to be important in the amplification of virus by this species.

Animals↗
PubMed1997

Life-table attributes of Anopheles albimanus (Wiedemann) under controlled laboratory conditions.

The life-table attributes of a laboratory-colonized strain of Anopheles albimanus Wiedemann from El Salvador were investigated under controlled environmental conditions (26 +/- 2 degrees C, 60 +/- 2% RH, and 16:8 L:D photoperiod). Larvae pupated seven days after eclosion and the adults emerged on day eight. Adult emergence success was 91% and sex ratio was not significantly different from 1:1. Females took a blood meal one day after emergence and laid eggs two days later. The mean time of reproduction was 10.8 days and the expectation of life at emergence was 18.8 and 14.1 days for females and males, respectively. The daily survivorship of females at emergence was 0.97, and their net reproductive rate, age at mean cohort reproduction, instantaneous rate of increase, and mean generation time was 309.2, 10.8 days, 0.319, and 18 days, respectively. The life expectancy of females 10 days after emergence was 13.4 days, and they were capable of taking four to six additional blood meals.

Animals↗