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Biomedical subjects

H Ahmad

Publications and source records attributed to H Ahmad.

At least 19 recordsLinked to original sources
PubMed2004

Factors affecting abundance and oviposition rates of a field population of the Old World screw-worm fly, Chrysomya bezziana (Diptera: Calliphoridae).

Sentinel cattle and a grid of swormlure-baited sticky traps were used to monitor a Malaysian population of the Old World screw-worm fly, Chrysomya bezziana Villeneuve. Observations were carried out on an isolated cattle station at monthly intervals during the period August 1996 to June 2000. The number of flies caught was unaffected by weather conditions at the time of trapping, but was positively correlated with the total rainfall and the average daily air temperature prevailing 15-28 days earlier, when trapped flies were still juveniles. Trap catches were biased in favour of females, but daily catch rates of both sexes increased significantly the longer traps were open, suggesting that efficacy was related to the differential volatility of the chemicals comprising swormlure. Oviposition on sentinel cattle occurred mostly in late afternoon or early evening but increased significantly as the wound aged. Oviposition rates were positively correlated with female catch rates, but the relationship was curvilinear, suggesting that fly populations may be subject to some form of density-dependent constraint. Consistent differences in oviposition rates on sentinel cattle at different localities on the cattle station suggested the existence of highly clumped, quasi-stationary populations. Differences in trap catches between traps located in pastoral areas and those sited in nearby oil palm or rubber plantations supported this interpretation of the data. These findings are discussed in relation to the use of the sterile insect technique for the control of screw-worm fly infestations.

Animals↗
PubMed2003

Primary pleural lymphomas.

Two patients are presented with primary low grade pleural B cell lymphomas with no history of a pyothorax.

Asbestos↗
PubMed2002

Intrinsic aging vs. photoaging: a comparative histopathological, immunohistochemical, and ultrastructural study of skin.

Cutaneous aging is a complex biological phenomenon affecting the different constituents of the skin. To compare the effects of intrinsic and extrinsic aging processes, a total of 83 biopsies were collected from sun-exposed and protected skin of healthy volunteers representing decades from the 1st to the 9th (6-84 years of age). Routine histopathology coupled with computer-assisted image analysis was used to assess epidermal changes. Immunoperoxidase techniques with antibodies against type I and type III collagens and elastin were used to quantitatively evaluate changes in collagen and elastic fibers and their ultrastructure was examined by transmission electron microscopy. Epidermal thickness was found to be constant in different decades in both sun-exposed and protected skin; however, it was significantly greater in sun-exposed skin (P = 0.0001). In protected skin, type I and III collagen staining was altered only after the 8th decade, while in sun-exposed skin the relative staining intensity significantly decreased from 82.5% and 80.4% in the 1st decade to 53.2% and 44.1% in the 9th decade, respectively (P = 0.0004 and 0.0008). In facial skin the collagen fiber architecture appeared disorganized after the 4th decade. The staining intensity of elastin in protected skin significantly decreased from 49.2% in the 1st decade to 30.4% in the 9th decade (P = 0.05), whereas in sun-exposed skin the intensity gradually increased from 56.5% in the 1st decade to 75.2% in the 9th decade (P = 0.001). The accumulated elastin in facial skin was morphologically abnormal and appeared to occupy the areas of lost collagen. Collectively, the aging processes, whether intrinsic or extrinsic, have both quantitative and qualitative effects on collagen and elastic fibers in the skin.

Adolescent↗
PubMed2002

Norditerpenoid alkaloids from the roots of Aconitum leave Royle.

From the roots of Aconitum leave Royle growing wild in Northern Pakistan, Swat district, three new alkaloids, 8-methyllycaconitine (1), 14-demethyllycaconitine (2), N-deethyllycaconitine-N-aldehyde (3) have been isolated along with four known compounds, lappaconitine (4), lycaconitine (5), lapaconidine (6) and lycoctonine (7).

Alkaloids↗
PubMed2001

Absorption, distribution, metabolism and excretion of daily oral doses of [14C]methyl parathion in hens.

Adult hens were given oral daily doses of 2 mg (2 microC(i))/kg/day (14% of oral LD(50) in male rats) of [14C]methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate) for 10 consecutive days. Five treated hens were sacrificed at 1, 2, 4, 8, 12, 24, and 48 h after the last dose. Methyl parathion was absorbed from the gastrointestinal tract and distributed rapidly. Maximum radioactivity was detected in tissues within 8 h of dosing, (ng methyl parathion equivalent/g fresh tissue or ml plasma): Plasma (189.2), liver (94.7), kidney (146.2), brain (61.4), gastrointestinal tissues (106.7). Methyl parathion was detected in the plasma, kidney and liver, while methyl parathion metabolite p-nitrophenol was detected in the liver and in the kidney. Elimination of methyl parathion from plasma was monophasic with a terminal half-life of 17.5 h, corresponding to an elimination rate constant of 0.039 ng/hr. Most of the absorbed radioactivity was excreted in the combined fecal-urine excreta (98%). Analysis of the metabolites in the excreta revealed that non-conjugated metabolites accounted for 13% of the total excretion. Conjugated metabolites accounted for 87% of the total excretion; of that, 6% as p-nitrophenyl-glucoronide conjugate, 7% as p-nitrophenyl-sulfate conjugate, 23% as bound hot sulfuric acid hydrolyzable residues, and 51% as water soluble metabolites. The presence of majority of radioactivity in the excreta as conjugated metabolites indicates that determining only unbound p-nitrophenol as a biological marker for methyl parathion exposure underestimates total fecal-urine excretion of p-nitrophenol. The slow elimination rate of methyl parathion is significant, since hens are more comparable to humans with respect to their cytochrome P450 activities.

Absorption↗
PubMed2001

Effects of methylenedioxymethamphetamine on noradrenaline-evoked contractions of rat right ventricle and small mesenteric artery.

We have compared the effects of methylenedioxymethamphetamine (MDMA) and cocaine on contractions to noradrenaline in 1 Hz paced rat right ventricular strips, and in rat small mesenteric artery and aorta. Noradrenaline increased the force of contraction of 1 Hz paced ventricular strips with a pD(2) (-log EC(50)) of 5.64+/-0.07. Both cocaine (10 microM) and MDMA (10 microM) significantly increased the potency of noradrenaline to 6.31+/-0.11 and 6.42+/-0.13, respectively. However, in the presence of cocaine (10 microM) which increased the potency of noradrenaline to 6.78+/-0.15, MDMA (10 microM) no longer increased the potency of noradrenaline (pD(2) of 6.78+/-0.32). Likewise, following chemical sympathectomy, MDMA failed to increase the potency of noradrenaline. The potency of the agonist isoprenaline, which is not a substrate for the noradrenaline transporter, was not increased by either cocaine or MDMA. In rat small mesenteric artery, but not aorta, MDMA and cocaine significantly increased the potency of noradrenaline, but in the presence of cocaine, MDMA had no further effect. Hence, MDMA shares with cocaine an ability to potentiate the actions of noradrenaline, an action in the case of MDMA which may involve competitive blockade of the noradrenaline transporter, rather than simply displacement of noradrenaline. Since cocaine is linked to an increased incidence of myocardial infarction, these results may have implications in terms of cardiac morbidity of MDMA.

Animals↗
PubMed2001

Citrus pectin: characterization and inhibitory effect on fibroblast growth factor-receptor interaction.

This study was undertaken to characterize the pectin from four citrus species and to determine their in vitro inhibitory activities on the binding of fibroblast growth factor (FGF) to the FGF receptor (FGFR). Pectin from various parts of lemon, grapefruit, tangerine, and orange were isolated and characterized. Tangerine had the highest pectin content among the four citrus species. Segment membrane contained as much as or more pectin than flavedo/albedo. Anhydrogalacturonic content was highest in pectin from segment membrane of tangerine and flavedo/albedo of grapefruit. Lemon pectin contained the highest methoxyl content (MC), and grapefruit contained the largest proportion of lower molecular weight (<10000 Da) pectin. Tangerine contained the highest neutral sugar in both flavedo/albedo and segment membrane. The interdependency of heparin on factor-receptor interaction provides a means for identifying new antagonists of growth factor activity and thus for treatment of various diseases. These results showed that pectin significantly inhibited the binding of FGF-1 to FGFR1 in the presence of 0.1 microg/mL heparin. The pectin from the segment membrane of lemon was the most potent inhibitor. The inhibition activity was significantly correlated with sugar content, MC, and size of pectin. Kinetic studies revealed a competitive nature of pectin inhibition with the heparin, a crucial component of the FGF signal transduction process. The observation that the heparin-dependent biological activity of FGF signal transduction is antagonized by citrus pectin should be further investigated for the use of these pectins as anti-growth factor agents for potential health benefits.

Citrus↗
PubMed2001

Differential inhibition of human cancer cell proliferation by citrus limonoids.

Limonoids have been shown to inhibit the growth of estrogen receptor-negative and -positive human breast cancer cells in culture. The primary objective of this study was to test the antiproliferative activity of limonoids (obacunone 17 beta-D-glucopyranoside, nomilinic acid 17 beta-D-glucopyranoside, limonin, nomilin, and a limonoid glucoside mixture), found in high concentrations in mandarin (Citrus reticulata Blanco), against a series of human cancer cell lines. The human cancer cell lines included leukemia (HL-60), ovary (SKOV-3), cervix (HeLa), stomach (NCI-SNU-1), liver (Hep G2), and breast (MCF-7). The growth-inhibitory effects of the four limonoids and the limonoid glucoside mixture against MCF-7 cells were significant, and the antiproliferative activity of the different citrus limonoids was also dose and time dependent. No significant effects were observed on growth of the other cancer cell lines treated with the four individual limonoids at 100 micrograms/ml. At 100 micrograms/ml, the limonoid glucoside mixture demonstrated a partial inhibitory effect on SKOV-3 cancer cells. With use of flow cytometry, it was found that all the limonoid samples could induce apoptosis in MCF-7 cells at relatively high concentrations (100 micrograms/ml). Considering the high concentration needed to induce apoptosis, it is unlikely that this is the primary mechanism of action for the cytotoxic effects seen with limonoids in this study. Further work is needed in this area to establish the mechanism of action of citrus limonoids on human breast cancer cells.

Apoptosis↗
PubMed2001

Candida lusitaniae catheter-related sepsis.

OBJECTIVE: To present a case describing Candida lusitaniae candidemia in an immunocompetent patient successfully treated with fluconazole antifungal therapy. Time-kill studies of the C. lusitaniae isolate using amphotericin B, and an extensive review of the literature are also presented. CASE SUMMARY: A 52-year-old immunocompetent Latin-American woman was admitted to the special care unit with severe sepsis. Her recent medical history included an exploratory laparotomy for gallstone pancreatitis, requiring cholecystectomy, segmental sigmoid colectomy, drainage of peritoneal abscesses, and a colostomy. In addition, the patient required a central venous catheter (CVC) placement for prolonged broad-spectrum antibiotic therapy and total parenteral nutrition therapy. Yeast was isolated from the abdominal abscess and blood cultures obtained on day 1, and from the catheter tip on day 5. The woman received initial empiric antifungal therapy with fluconazole, which was later changed to amphotericin B. After the yeast was identified as C. lusitaniae on day 8, this was changed to fluconazole for the duration of therapy. C. lusitaniae was not present in blood cultures taken two weeks after the CVC was removed, and the cultures remained negative thereafter. After a prolonged hospitalization, the patient was discharged home. DISCUSSION: Disseminated infections with C. lusitaniae usually occur in immunocompromised patients, although isolated reports of C. lusitaniae infections in immunocompetent patients have been described. Therapeutic challenges of C. lusitaniae treatment include its primary resistance to amphotericin B and species misidentification. Isolates recovered from our patient were submitted for fungus time--kill studies that suggested unique susceptibility patterns to amphotericin B, indicating a trend toward resistance. CONCLUSIONS: Based on variable susceptibility patterns of C. lusitaniae to amphotercin B and flucytosine, fluconazole is an appropriate choice as first-line therapy for C. lusitaniae candidemia.

Amphotericin B↗
PubMed2001

Pneumocystis carinii pneumonia in pregnancy.

OBJECTIVE: To report five new cases of Pneumocystis carinii pneumonia (PCP) and to review and analyze the existing reports on the subject. METHOD: Five new cases of PCP during pregnancy are described. The cases, case series, and related articles on the subject in the English language were identified through a comprehensive MEDLINE search and reviewed. RESULTS: More than 80% of women with AIDS are of reproductive age, and PCP is the most common cause of AIDS-related death in pregnant women in the United States. Among 22 reviewed cases, the mortality rate was 50% (11 of 22 patients), which is higher than that usually reported for HIV-infected individuals with PCP. Respiratory failure developed in 13 patients (59%), and mechanical ventilation was therefore required, and the survival rate in patients requiring mechanical ventilation was 31%. Maternal and fetal outcomes were better in cases of PCP during the third trimester of the pregnancy. A variety of treatment regimens were used, including sulfamethoxazole-trimethoprim (SXT) alone or in combination with pentamidine, steroids, and eflornithine. The survival rate in patients treated with SXT alone was 71% (5 of 7 patients) and for those treated with SXT and steroids was 60% (3 of 5 patients), with an overall survival rate in both groups of 66.6% (8 of 12 patients). CONCLUSION: PCP has a more aggressive course during pregnancy, with increased morbidity and mortality. Maternal and fetal outcomes remain dismal. Treatment with SXT, compared to other therapies, may result in an improved outcome. Withholding appropriate PCP prophylaxis may adversely affect maternal and fetal outcomes.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Predictive value of repeat renal biopsies in children with nephrotic syndrome.

In children who exhibit a frequently relapsing course of minimal change disease (MCD), treatment is often difficult and frustrating to the physician and the family since the goal of a sustained remission remains elusive. The progression of the disease is often unpredictable from its clinical presentation since the lesion of MCD may evolve into a more severe form, such as mesangial IgM nephropathy or focal segmental glomerulosclerosis (FSGS), without alteration in signs and symptoms. Alkylating agents such as cyclophosphamide, or immunosuppressives such as cyclosporine can induce a more sustained remission, but are fraught with inherent toxicity, which makes difficult the decision to use these drugs in patients with MCD. Over a 10-year period we studied 49 patients who had more than one renal biopsy. Repeat biopsies were performed either to delineate the morphological lesion prior to change in therapy, or to confirm suspected drug toxicity, which would necessitate discontinuation of therapy. A total of 83 repeat biopsies were performed in these 49 patients. Of the 49 patients, 25 had MCD, and in 21 of these the lesion evolved into either IgM nephropathy (n = 7) or FSGS (n = 14). Of patients with IgM nephropathy (n = 12), 50% evolved into FSGS. The clinical diagnosis made prior to the repeat biopsy did not confirm with the histological diagnosis in 43% of cases, and a change in therapy or cessation of therapy was carried out in 43 of 83 repeat biopsy instances. Since the complications were mild and the ability of clinical findings to accurately predict the histological lesion limited, we conclude that repeat renal biopsies are a useful tool to fashion optimal therapy in children with frequently relapsing nephrotic syndrome.

Adolescent↗
PubMed2000

Intrahepatic stones: the UKM experience.

Intrahepatic stones remain a major source of morbidity and mortality. With improving techniques in hepatobiliary surgery, the management and the outcome of intrahepatic calculi is reviewed. Forty-nine cases referred from all over Malaysia between January 1993 to June 1996 were analyzed retrospectively. There were thirty-two females and seventeen males. The median age was 46 years. Biliary diseases encountered in association with intrahepatic calculi included benign strictures (n = 14), ascariasis (n = 3), cholangiocarcinoma (n = 1), Caroli's disease (n = 1), and thalassaemia, (n = 1), fifty-six percent of stones were located in both the intrahepatic ducts while 34% were found in the left intrahepatic duct. Thirty-one patients underwent common bile duct exploration either alone or in combination with liver resection or bilioenteric anastomosis. Despite the various combinations of surgical and non-surgical intervention 28 (57.1%) patients had residual stones. Despite the availability of newer techniques in hepatobiliary surgery, residual stones were common, resulting in higher treatment costs.

Adult↗
PubMed1999

Conjugated polysaccharide vaccines.

The joining of polysaccharide antigens to various proteins can result in increased immunogenicity of vaccines composed of such antigens. This article discusses conjugated polysaccharide vaccines for Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitis. Increased availability and use of such vaccines may result in the ability to give more effective vaccines earlier in life, further reducing the incidence of diseases caused by these organisms.

Adult↗
PubMed1999

Trauma in the elderly: a new epidemic?

Australia's population is ageing. Statistics predict that by the year 2021, 17.8% of our population will be over the age of 65 years. These statistics are reflected in most Western nations. The elderly represent an increasing proportion of emergency department patients. They are generally more acute on presentation, they get admitted more frequently, and account for an increasing proportion of admissions to intensive care units. The elderly trauma patient will increasingly consume more resources than patients from any other age group. There are significant differences in physiology and response to trauma between the elderly patient and the young. Airway compromises, a decrease in lung compliance, a change in cardiovascular haemostasis and the prevalence of pre-existing disease all contribute to increase morbidity and mortality in a patient with an already limited physiological reserve. Many studies demonstrate an increased mortality in hospitalized elderly trauma patients. For those who die from traumatic insult, death is mainly due to multiorgan system failure. The long-term functional outcome of the elderly trauma patient has been investigated by a number of authors. One study showed that only 8% of survivors returned to independent living 1 year post-polytrauma. Another more encouraging study showed that 89% of survivors of blunt multiple trauma after 38 months were independent and living at home. Ethical issues have been raised regarding the appropriateness of care for the severely injured elderly patient given today's ever-shrinking hospital finances and bed shortages. Today's environment is very challenging as frequently, the clinician is forced to make an economic decision on who will take the last critical care bed, which is a far from optimal situation.

Age Factors↗
PubMed1999

Characteristics of acute pancreatitis in University Kebangsaan Malaysia.

We analyzed the characteristics of patients presenting with acute pancreatitis to our unit. A total of 71 patients were admitted to the Surgical Department at University Kebangsaan Malaysia (UKM) over a period of seven years, between January 1990 to December 1996 with acute pancreatitis. There was a fourfold increase in incidence of acute pancreatitis in our hospital from January 1990 to December 1996. The commonest identifiable aetiology was gallstones followed by alcohol. There were two deaths. We conclude that acute pancreatitis is increasingly being diagnosed in our local population. This may be due to either greater awareness or changes in lifestyle of the population.

Acute Disease↗
PubMed1999

Radical resection for naso-lacrimal duct tumour.

Naso-lacrimal duct tumours are uncommon and present with epiphora and swelling. Since the naso-lacrimal duct is embedded in bone for the majority of its anatomical length, the late presentation of proptosis is due to orbital extension of the tumour. Radical surgical treatment is necessary to establish clear margins and facilitate reconstruction.

Eye Neoplasms↗
PubMed1998

The paucity of minimal change disease in adolescents with primary nephrotic syndrome.

Data are sparse regarding the histological lesions associated with the primary nephrotic syndrome in adolescents. To our knowledge there are only two published articles that have specifically addressed the histopathological lesions that typify idiopathic nephrotic syndrome in the adolescent population. We reviewed our experience from the last 14 years of children between the ages of 12 and 18 years who were referred to our center for the evaluation of the nephrotic syndrome. A total of 29 adolescents met the inclusion criteria for this review. All patients were biopsied prior to the initiation of treatment. The sex ratio consisted of 52% males and 48% females and the racial breakdown was largely African-American, with 83% black adolescents, 7% Hispanic, and 10% Caucasian patients. Minimal change nephrotic syndrome (MCNS), the predominant lesion of children at an early age, was noted in only 20% of patients. The majority of patients (55.2%) had focal segmental glomerulosclerosis (FSGS); 7% had IgM nephropathy and 3.5% had diffuse mesangial hypercellularity. Only 7% of biopsied adolescents had membranoproliferative glomerulonephritis. Our results indicate that the most common lesion in this predominantly African-American patient population is FSGS, with only a small number showing MCNS. Thus, in our experience derived from a racially mixed population, adolescents with the nephrotic syndrome are less likely to have MCNS than younger children.

Adolescent↗