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Biomedical subjects

J Iqbal

Publications and source records attributed to J Iqbal.

At least 55 records · Page 3Linked to original sources
PubMed2000

Indoor residual spraying with alphacypermethrin controls malaria in Pakistan: a community-randomized trial.

We conducted a community-randomized controlled trial in Pakistan to determine the efficacy of indoor residual spraying with alphacypermethrin ('Fendona', Cyanamid, NJ, USA), applied at 25 mg/m2, to prevent falciparum and vivax malaria. Wettable powder (WP) and suspension concentrate (SC) formulations were tested against an unsprayed control in an irrigated rice-growing area of Sheikhupura district, Punjab province. The study area of 180 km2 was divided into nine sectors, which were assigned at random to control, WP, or SC treatments in replicates of 3. Sentinel villages were selected from each sector for entomological and disease monitoring. Malaria was monitored by fortnightly active case detection (ACD) and by cross- sectional parasite surveys on schoolchildren. Mosquito populations were monitored by space spraying of rooms and by cattle-landing catches. The spray campaign took place in June 1997 and covered 96% of compounds. During the 7 months after spraying, the incidence of falciparum malaria was 95% lower and that of vivax malaria 80% lower in WP-sprayed than unsprayed sectors. Similar results were obtained for sectors sprayed with the SC formulation. Cross-sectional surveys gave estimates of efficacy comparable to those obtained by ACD. Anopheles culicifacies was 80% less abundant and A.stephensi, the predominant anopheline, was up to 68% less abundant in sprayed areas over the 7-month period. Reductions in anopheline parous rates indicated that the single-spray treatment was effective for the entire transmission season. Sprayed surfaces lacked odour, which contributed to the popularity of the campaign. Alphacypermethrin is a promising insecticide for the control of malaria in Pakistan and South Asia generally.

Animals↗
PubMed2000

Intraparenchymal pericatheter cyst. A rare complication of ventriculoperitoneal shunt for hydrocephalus.

Intraparenchymal pericatheter cyst is rarely reported. Obstruction in the ventriculoperitoneal shunt leads to recurrence of hydrocephalus, signs of raised intracranial pressure and possibly secondary complications. Blockage of the distal catheter can result, unusually, in cerebrospinal fluid oedema and/or intraparenchymal cyst around the ventricular catheter which may produce focal neurological deficit. We report two cases of distal catheter obstruction with formation of cysts causing local mass effect and neurological deficit. Both patients had their shunt system replaced, which led to resolution of the cyst and clinical improvement. One patient had endoscopic exploration of the cyst which confirmed the diagnosis made on imaging studies. Magnetic resonance imaging was more helpful than computed tomography in differentiating between oedema and collection of cystic fluid. Early recognition and treatment of pericatheter cyst in the presence of distal shunt obstruction can lead to complete resolution of symptoms and signs.

Central Nervous System Cysts↗
PubMed2000

Plasmodium falciparum histidine-rich protein 2-based immunocapture diagnostic assay for malaria: cross-reactivity with rheumatoid factors.

Recently introduced rapid nonmicroscopic immunocapture assays for the diagnosis of malaria infection are being evaluated for their sensitivity and specificity in various epidemiological settings. A Plasmodium falciparum histidine-rich protein 2 (PfHRP-2)-based assay (ICT) and a Plasmodium-specific lactate dehydrogenase test (OptiMAL) were evaluated for their specificities in different groups of patients who tested negative for malaria infection by microscopy. The patients were selected from different disease groups: rheumatoid arthritis, hepatitis C, toxoplasmosis, schistosomiasis, and hydatid disease. One hundred thirty-three of the 225 patients were positive for rheumatoid factor. Thirty-five of the 133 (26%) rheumatoid factor-positive patients gave a false-positive reaction with the ICT assay, but only 4 of these gave false-positive reactions with the OptiMAL test. Thirty-three of the 35 false-positive specimens became negative when repeat tested with the ICT assay after absorbing out the rheumatoid factor activity. Our study shows that the PfHRP-2-based ICT assay gave a false-positive reaction in 26% of the patients who had rheumatoid factors, but were negative for malaria by microscopy.

Animals↗
PubMed2000

Localization of leptin receptor-like immunoreactivity in the corticotropes, somatotropes, and gonadotropes in the ovine anterior pituitary.

Leptin is a secreted product of the adipocytes that regulates a variety of functions. The presence of the leptin receptor (LR) has been demonstrated in the endocrine and neuroendocrine tissue, but only limited information is available regarding cell-specific expression in the anterior pituitary gland. We have used double-label immunofluorescence histochemistry to study the distribution of LR-like immunoreactivity (LR-ir) in the corticotropes, somatotropes, and gonadotropes of the ovine anterior pituitary. LR-ir was found in 34% of cells in the pars distalis and 94% of the cells in the pars tuberalis. In the pars distalis, LR-ir was present in 27% of corticotropes, 69% of somatotropes, and 29% of gonadotropes. In contrast, 90% of the gonadotropes in the pars tuberalis were immunopositive for LR. There was no alteration in the number of gonadotropes containing LR-ir during the various phases of the estrous cycle (n = 3/group) in the pars distalis (luteal phase, 36%; follicular phase, 32%; and estrous phase, 32%). In conclusion, we show that, in the pars distalis, LR-ir is expressed to a greater extent in the somatotropes than in the gonadotropes or corticotropes. This is in accordance with the documented effects of leptin on pituitary GH secretion. The differential expression of LR-ir between the gonadotropes of the pars distalis and pars tuberalis probably reflects the different phenotypes of the cells in these two regions. Lower levels of LR-ir expression in gonadotropes and corticotropes of the pars distalis may suggest that leptin does not substantially influence these particular cells, at least in this species.

Adrenocorticotropic Hormone↗
PubMed1999

Non-neoplastic cystic lesions of the sellar region presentation, diagnosis and management of eight cases and review of the literature.

The differential diagnosis of a sellar lesion includes pituitary adenoma, cranio-pharyngioma, tumour cyst, benign cyst, and other less common lesions such as aneurysm, squamous cell carcinoma and metastases. Pure cystic lesions within the sella turcica are not uncommon and may appear clinically and radiologically as pituitary adenoma. Intrasellar cysts are broadly classified as neoplastic or non-neoplastic; the latter may be primary lesions of the pituitary fossa or they may arise from the parasellar region and invade into the sella. The lesions occupy space and may cause disturbance of pituitary function; if they extend into the suprasellar region they can affect visual fields and acuity. Non-neoplastic cystic lesions usually appear well defined radiologically and have distinct pathological features. Modern imaging modalities, such as computed axial tomography and magnetic resonance imaging, are important complementary tools of investigation for reaching a differential diagnosis, and for surgical planning. Most non-neoplastic sellar cysts can be approached through the trans-sphenoidal route, but large lesions with suprasellar extension may require transcranial surgery. We report the presentation and management of eight cases (four males, four females, all adult) of non-neoplastic cyst involving the sella turcica and the parasellar region. Investigations included computed tomography scan of the head for all and magnetic resonance imaging for six (75%) patients. Work-up included endocrinological and opthalmological evaluations. All presented with headache; six (75%) had visual acuity change, two (25%) had evidence of visual field defects, four (50%) had optic atrophy on fundoscopy, three (37.5%) had endocrine symptoms and hormone reduction was found in four (50%).

Adult↗
PubMed1999

Osteoplastic laminotomy as a minimally invasive spinal procedure.

A minimally invasive surgical technique is demonstrated to perform osteoplastic laminotomy. It consists of protection of the dural sac and the nerve roots with a rubber or silicone tube, cutting of the laminae with an oscillating saw and bilateral refixation of the laminae. This simple and safe technique, which has been used by the authors for six years, provides good stability of the spine postoperatively and helps to avoid post-laminectomy membrane formation.

Arachnoid Cysts↗
PubMed1999

Comparison of the OptiMAL test with PCR for diagnosis of malaria in immigrants.

The OptiMAL test (Flow Inc., Portland, Oreg.), which detects a malaria parasite lactate dehydrogenase (pLDH) antigen, has not been evaluated for its sensitivity in the diagnosis of malaria infection in various epidemiological settings. Using microscopy and a PCR as reference standards, we performed a comparison of these assays with the OptiMAL test for the detection of Plasmodium falciparum and Plasmodium vivax infection in 550 immigrants who had come from areas where malaria is endemic to reside in Kuwait, where malaria is not endemic. As determined by microscopy, 125 (23%) patients had malaria, and of these, 84 (67%) were infected with P. vivax and 36 were infected with P. falciparum; in 5 cases the parasite species could not be determined due to a paucity of the parasites. The PCR detected malaria infection in 145 (26%) patients; 102 (70%) of the patients had P. vivax infection and 43 had P. falciparum infection. Of the five cases undetermined by microscopy, the PCR detected P. falciparum infection in two cases, P. vivax infection in two cases, and mixed (P. falciparum plus P. vivax) infection in one case. Correspondingly, the OptiMAL test detected malaria infection in 95 patients (17%); of these, 70 (74%) had P. vivax infection and 25 were infected with P. falciparum. In this study, 61 (49%) of the 125 malaria cases, as confirmed by microscopy, had a degree of parasitemia of <100 parasites per microl, and 23 (18%) of the cases had a degree of <50 parasites per microl. Our results show that the sensitivity of the OptiMAL test is high (97%) at a high level of parasitemia (>100 parasites/microl) but drops to 59% when the level is <100 parasites/microl and to 39% when it is <50 parasites/microl. In addition, the OptiMAL test failed to identify four patients whose blood smears contained P. falciparum gametocytes only. We conclude that the sensitivity and specificity of the OptiMAL test are comparable to those of microscopy in detecting malaria infection at a parasitemia level of >100 parasites/microl; however, the test failed to identify more than half of the patients with a parasitemia level of <50 parasites/microl. Thus, the OptiMAL test should be used with great caution, and it should not replace conventional microscopy in the diagnosis of malaria infection.

Animals↗
PubMed1999

Cryptosporidium infection in young children with diarrhea in Rawalpindi, Pakistan.

Fecal excretion of Cryptosporidium parvum oocysts was determined in 625 children less than five years old who presented at the pediatric clinic of a teaching hospital in Rawalpindi, Pakistan. Single stool specimens were collected from 475 children with acute diarrhea and from 150 children without diarrhea. The Cryptosporidium infection rate was significantly higher in children with diarrhea than in children without diarrhea (10.3% versus 3.3%). The C. parvum infection rate was highest in children 19-24 months of age (21.8%). There was no significant difference in the Cryptosporidium infection rate among male and female children of any age group studied. Sociodemographic information, drinking water supply, and contact with domestic animals had no significant role in the acquisition of C. parvum infection in our study population. The data suggest that C. parvum is relatively endemic in young children in the Rawalpindi area and that C. parvum may be an important pathogen associated with diarrhea.

Animals↗
PubMed1998

Antibodies to nonrepeat sequences of antigen Pf155/RESA of Plasmodium falciparum inhibit parasite growth in vitro.

Immune responses to the repeat regions of the Plasmodium falciparum antigen Pf155/RESA have been extensively studied, and antibodies to the repeats are known to interfere with parasite growth both in vitro and in vivo. Less is known with regard to the effect on parasites of antibodies to the nonrepeat regions of the antigen. In the present study, rabbits were immunized with synthetic peptides corresponding to three different nonrepeated sequences of antigen Pf155/RESA. The reactivity of the antibodies with the particular peptides was analyzed by enzyme-linked immunosorbent assay (ELISA) and that with the parasite antigen, by immunoblotting and immunofluorescence. Although all antisera reacted strongly with the corresponding synthetic peptides, they reacted only weakly with full-length Pf155/RESA in either of the methods used. The specificity of the antibodies for Pf155/RESA was confirmed by their failure to stain Pf155/RESA-deficient parasites in erythrocyte membrane immunofluorescence, a method mainly detecting this antigen. Antibodies to the nonrepeat sequences also efficiently inhibited the merozoite invasion in vitro of Pf155/RESA+ parasites. However, these antibodies also inhibited Pf155/RESA-deficient parasites, indicating the presence of an antigen exhibiting a high degree of homology with Pf155/RESA. The results indicate that nonrepeat sequences of Pf155/RESA are immunogenic and may serve as targets for parasite-neutralizing antibodies, and, thus, the potential of the antigen as a vaccine candidate is emphasized.

Amino Acid Sequence↗
PubMed1998

The equid herpesvirus-1 gene 63 is expressed as a leaky late (gamma 1) transcript and is nonessential for replication in vitro.

The regulation of Equid herpesvirus-1 (EHV-1) gene 63 was investigated using molecular expression studies and its role in viral growth was identified by constructing a gene 63 mutant virus. Metabolic inhibitors were used to show that EHV-1 gene 63 is expressed as a leaky-late (gamma 1) transcript. Transient transfections and subsequent chloramphenicol acetyltransferase (CAT) reporter assays showed that gene 63 was transactivated by EHV-1 gene 64 (immediate early) protein. An EHV-1 gene 63 mutant virus, where the LacZ gene was inserted into the mutated gene 63 open reading frame, showed that gene 63 protein was not essential for efficient EHV-1 growth in tissue culture. These findings indicate that the animal alpha herpesviruses may have evolved different pathways leading to replication.

Animals↗
PubMed1998

Hepatic resection with cryotherapy to involved or inadequate resection margin (edge freeze) for metastases from colorectal cancer.

BACKGROUND: In patients undergoing liver resection for colorectal liver metastases, a resection edge either involved by tumour or with the tumour extending to within 1 cm is associated with a high risk of liver recurrence and survival is reduced markedly. METHODS: Twenty-six patients underwent cryotherapy of the resection edge following liver resection for metastases from colorectal carcinoma with an involved or inadequate (less than 1 cm) resection margin. RESULTS: At a median follow-up of 23 (range 1-47) months four patients were alive and disease free, and 21 had developed recurrence, of whom 13 had died. One patient died following surgery. Sixteen patients developed recurrences involving the liver, only five of which were at the resection margin. CONCLUSION: Cryotherapy to involved or inadequate resection margins improves local disease control considerably. The use of resection edge cryotherapy might allow a greater proportion of patients with liver metastases to be usefully treated and help to avoid high-risk resections.

Adult↗
PubMed1998

Neurosurgical aspects of sphenoid sinus mucocele.

The aetiological spectrum of sphenoid sinus mucocele includes congenital anomaly, trauma, infection, allergy and surgery of the sphenoid sinus. Enlargement of the mucocele, even with a short history, can result in progressive expansion of the sinus and extension of the lesion into the pituitary fossa, the suprasellar region, nasopharynx, orbits, clivus or ethmoid air cells. It is a benign cystic lesion with an excellent prognosis when treated appropriately. Generally, these lesions are managed by an ear, nose and throat surgeon, but when there is extension into the sellar and parasellar (especially suprasellar) regions they are managed by the neurological surgeon. Sphenoid sinus mucocele should be considered in the differential diagnosis when there is suspicion of a cystic lesion in these regions. Three cases of large sphenoid sinus mucocele are presented, with discussion on their neurosurgical management and a review of the literature.

Adult↗
PubMed1998

In vitro reactivation of latent equid herpesvirus-1 from CD5+/CD8+ leukocytes indirectly by IL-2 or chorionic gonadotrophin.

IL-2 and equine chorionic gonadotrophin (eCG) initiated reactivation of equid herpesvirus-1 (EHV-1) from venous lymphocytes at a frequency of 1/10(-5). Indirect immunofluorescence showed that > 80% of virus-positive leukocytes were CD5+/CD8+ with the remaining 20% being CD5+/CD8-/CD4-. Cocultivation demonstrated that the reactivated virus was infectious. In addition, virus was reactivated in vitro from leukocytes of > 70% of horses by the mitogens phytohaemagglutinin (PHA) and pokeweed mitogen (PWM). Transfer of supernatants showed that IL-2 and eCG acted indirectly by causing the release of other mediators from adherent cells; these mediators then reactivated EHV-1 from T cells. Blocking experiments with anti-IL-2 showed that PWM and PHA acted via IL-2 but that eCG did not. This is the first clear definition of the lymphoid cells that harbour latent EHV-1 in vivo and correlates with current RT-PCR and in situ hybridization of latency-associated transcripts in lymphocytes. This method of reactivation in vitro can be used to detect horses carrying latent EHV-1 in vivo and also has the potential to dissect the sequence of events involved in reactivation in vitro.

Animals↗
PubMed1998

A semisynthetic fetal calf serum-free liquid medium for in vitro cultivation of Leishmania promastigotes.

A semisynthetic, autoclavable, liquid medium that does not require inclusion of fetal calf serum (FCS) for the successful cultivation of Leishmania promastigotes in vitro is described. The parasites were grown in commercially available medium 199 supplemented with 10% FCS and 2% mammalian urine and the growth was compared with the same medium without FCS. The growth of the parasites in the semidefined medium without FCS was found to be as good as or slightly better that with medium 199 supplemented with FCS.

Animals↗
PubMed1997

Assessment of blood flow velocities in the ophthalmic arteries by transcranial Doppler sonography in osteopetrosis.

Osteopetrosis is a rare congenital disorder of bone resorption, which causes generalized hyperostosis. One of its many complications involves the skull base and progressive encroachment of the optic nerves within their canals, resulting in optic atrophy and blindness. Management of patients with deteriorating vision may include surgical decompression of the optic canals; their selection requires careful assessment by radiology, computed tomography, visual evoked potentials, electroretinography and possibly haemodynamic studies of the ophthalmic arteries. Postoperative changes can create difficulty in the interpretation of follow-up radiological investigations. In this study, transcranial Doppler sonography was used to assess the blood flow velocities in the ophthalmic arteries non-invasively. Pre- and postoperative studies of the Doppler parameters were done for each ophthalmic artery in a 5-month-old boy under standard physiological conditions. He presented with almost complete blindness and subsequently showed a good outcome following surgical intervention.

Blood Flow Velocity↗
PubMed1997

Plasmodium falciparum: selection of parasite subpopulations with decreased sensitivity for antibody-mediated growth inhibition in vitro.

The chronic, recrudescent nature of malaria has been linked to antigenic diversity of the parasite in which protective immunity against Plasmodium falciparum may be obtained after repeated exposure to infection during a long time. In this study we show that parasite populations with decreased sensitivity to antibody-mediated growth inhibition are readily generated in vitro. A laboratory strain, F32, was cultured for long periods (10-12 weeks) in the presence of suboptimal inhibitory antibody concentrations. The antibodies used were the human monoclonal antibody 33G2 reacting with a linear epitope of the P. falciparum blood-stage antigen 332 and rabbit antibodies to repeat sequences of the blood-stage antigen Pf155/RESA. Our data indicate that the P. falciparum parasites adapt to antibody pressure as reflected by their specifically decreased sensitivity to growth inhibition. A relative resistance of the parasite to growth inhibition mediated by the antibodies used in the culture developed successively, while the parasite remained sensitive to growth inhibition by other antibodies. When the antibody pressure was removed a successive return of sensitivity to growth inhibition developed. Immunoflourescence did not reveal any significant difference in antigen expression between the parasite populations. However, PCR analysis showed that a new population appeared in the parasites grown in the presence of mAb 33G2, while no such change was detected in those grown in the presence of the rabbit antibodies. Our data suggest that the specific decrease in sensitivity to growth inhibition may either be due to down-regulation of antigen synthesis or expression by antibody pressure or, that antibody pressure selects for parasites with low expression of a specific antigen from a heterogeneous parasite population.

Animals↗