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Biomedical subjects

I Ahmad

Publications and source records attributed to I Ahmad.

At least 91 records · Page 5Linked to original sources
PubMed2000

Survival and differentiation of cultured retinal progenitors transplanted in the subretinal space of the rat.

We have shown that embryonic retina contains progenitors which display stem cell properties in vitro. These cells are proliferative and in addition to expressing the neuroectodermal marker, nestin, are multipotential. These properties and the fact that the putative stem cells can differentiate as photoreceptors when exposed to conducive environment identify them as a viable transplantation reagents to address degenerative retinal diseases. Here we report the survival and differentiation of cultured retinal progenitors upon subretinal transplantation. The retinal progenitor grafts, either as neural spheres or in the form of dissociated cells, survived without disrupting the morphology and laminar organization of the host retina. They did not form rosettes, the morphological barrier to the reconstruction of the normal anatomy of the retina. In addition, transplanted progenitors expressed photoreceptor-specific markers, suggesting that progenitors have the potential to differentiate as photoreceptors. Our observations suggest that cultured retinal progenitors can be a viable reagents for therapeutic transplantation.

Animals↗
PubMed2000

The 44Ti(alpha,p) reaction and its implication on the 44Ti yield in supernovae

Cross sections for the 44Ti(alpha,p)47V reaction which significantly affects the yield of 44Ti in supernovae were measured in the energy range 5.7 MeV</=E(c.m.)</=9 MeV, using a beam of radioactive 44Ti. The cross sections and the deduced astrophysical reaction rates are larger than the results from theoretical calculations by about a factor of 2. The implications of this increase in the reaction rate for the search of supernovae using space-based gamma detectors are discussed.

Journal Article↗
PubMed2000

Study of water quality of Hudiara drain, India-Pakistan.

This paper examines the extent of pollution in Hudiara drain water due to untreated industrial and sewage waste of India and Pakistan. Ninety-nine surface water samples from the Pakistani side of the Hudiara drain were collected during September 1997, and April and June 1998. The analytical results of the Hudiara drain samples point out the industrial and sewage inputs from India and Pakistan. Higher values of biochemical oxygen demand (BOD), chemical oxygen demand(COD), total organic carbon(TOC), and trace metals in drain samples from the Indo-Pak border clearly indicate the Indian industrial and sewage pollution. Large variations in the levels of various measured parameters (COD, BOD, TOC, pH, total soluble substances, and trace metals) were observed along the Hudiara drain in the Pakistani vicinity. These variations were due to different types of industrial effluents and small village drains. The study showed that suspended solids(SS), COD, and fecal coliform (FC) were the major pollutants. Accordingly, the most feasible alternative is to convert the drainage network to a sedimentation and temporary storage reservoir. If disinfected, the runoff water can be used for restricted irrigation. Groundwater samples taken from the drain's surrounding area have also been analyzed. Thirty percent of the samples are not fit for drinking purposes due to NO3-N, Se and FC counts as prescribed by World Health Organization (WHO) guidelines. A trilinear diagram clearly indicates the influence of surface water of the Hudiara drain on ground water; moreover, higher values of nitrate and FC clearly indicate the seepage from the Hudiara drain.

Environmental Monitoring↗
PubMed2000

Abdominoperineal electrical injury involving urogenital organs.

Although the incidence of electrical burns is not very high this incidence is rising in India. The residual effects of electrical burns are sometimes very severe and long lasting, if not managed properly. This case report is of a patient who sustained severe electrical burns over his left arm, lower abdomen and perineal area. The injuries were so severe that life-saving disarticulation of the limb together with excision of the involved pubic bone and genitalia and suprapubic urinary diversion was done. During follow up an unusual finding was noticed. There was a peritubal leak with no drainage from the catheter and on removal of the catheter, a manual examination of the urinary bladder revealed a stone which was removed at the same time. Following removal of the stone two ureteric openings with the trigone were seen and it was concluded that the granulating tissue was actually the posterior wall of the bladder. This was then mobilized and reposited into the abdomen. The deficient lower abdomen was reconstructed with a tensor fascia lata flap. A penile reconstruction for the patient is under consideration.

Abdominal Injuries↗
PubMed2000

Effect of riboflavin on the photolysis of folic acid in aqueous solution.

A study of the photolysis of folic acid in aqueous solution by visible radiation in the presence of riboflavin has been made. The second-order rate constants for the bimolecular interaction of folic acid and riboflavin have been determined in the pH range 4.0-9.0. The rate pH profile shows a gradual increase in the rate up to pH 6.2 (pHmax) followed by a decrease up to pH 9.0, depending upon the susceptibility of ionic species involved in the interaction. The rate of photolysis varies from 0.50 x 10(3) M(-1) min(-1) (pH 9.0) and 0.63 x 10(3) M(-1) min(-1) (pH 4.0) to 3.0 x 10(3) M(-1) min(-1) (pH 6.2) in the pH range studied. A HPLC method has been used for the assay of folic acid and its photoproducts, pterine-6-carboxylic acid and p-aminobenzoyl-L-glutamic acid in the presence of riboflavin.

Chromatography, High Pressure Liquid↗
PubMed2000

Detection of xanthomegnin in epidermal materials infected with Trichophyton rubrum.

Xanthomegnin, a mutagenic mycotoxin best known as an agent of nephropathy and death in farm animals exposed to food-borne Penicillium and Aspergillus fungi, was first isolated about 35 y ago as a diffusing pigment from cultures of the dermatophyte, Trichophyton megninii. This study investigates the production of xanthomegnin by the most common dermatophytic species, Trichophyton rubrum, both in dermatologic nail specimens and in culture. In view of the labile nature of xanthomegnin, a chromatographic procedure was developed to allow high-performance liquid chromatography analysis within 1 h of sample extraction. In cultures, Tricho- phyton rubrum produced xanthomegnin as a major pigment that appears to give the culture its characteristic red colony reverse. Xanthomegnin was also repeatedly extracted from human nail and skin material infected by Trichophyton rubrum. The level of xanthomegnin present, however, varied among the clinical samples studied. Xanthomegnin was not detected in uninfected nails. These results show that patients with Trichophyton rubrum infections may be exposed to xanthomegnin, although the consequences of such an exposure are not currently known.

Chromatography, High Pressure Liquid↗
PubMed2000

Acute rejection-associated tubular basement membrane defects and chronic allograft nephropathy.

BACKGROUND: Acute rejection is a major risk factor for chronic allograft nephropathy, although the link(s) between these events is not understood. The hypothesis of this study is that alterations in tubular basement membranes (TBMs) that occur during acute rejection may be irreversible and thereby play a role in the development of chronic allograft nephropathy. METHODS: Fourteen renal transplant patients were selected, each having had two or more biopsies performed (42 total). All biopsies were scored for acute and chronic rejection using Banff 1997 criteria. The initial biopsy showed only acute interstitial rejection (type I rejection). No biopsies contained significant chronic arterial lesions of chronic vascular rejection. The entire cortex was examined on Jones methenamine silver-stained sections at x400 for interruption in TBM staining. The number of tubules with TBM abnormalities was counted, and the renal cortical area was measured by image analysis. Periodic acid-Schiff/immunoperoxidase stain was performed on 12 acute rejection biopsies stained for laminin, cytokeratin 7, CD3, CD20, and CD68. Controls consisted of 11 biopsies (8 negative for rejection and 3 acute tubular necrosis). RESULTS: Numerous TBM alterations in silver staining were identified as being associated with acute rejection and tubulitis, consisting of abrupt TBM discontinuities and/or extreme attenuation with segmental or complete absence of TBM. A loss of TBM matrix proteins was confirmed by absent laminin staining in areas of acute rejection and tubulitis. There was herniation of tubular cells into the interstitium through TBM defects confirmed by cytokeratin staining. The TBM defects were spatially associated with inflammatory cells, particularly macrophages. When the biopsies were divided into two groups, <10 and> 10 TBM breaks/mm2, there were statistically significant morphologic and clinical correlations. The number of TBM disruptions correlated with the serum creatinine at the time of biopsy, a combined Banff t + i score, the difference in tubular atrophy between the initial and most recent biopsy and the difference between the nadir creatinine and most recent creatinine. CONCLUSION: Damage to TBM develops in acute rejection as a consequence of interstitial inflammation and tubulitis. These lytic events correlate with the later development of clinical and morphologic evidence of chronic injury in the absence of arterial injury of chronic rejection. We suggest that chronic allograft nephropathy may have an inflammatory interstitial origin.

Acute Disease↗
PubMed2000

Attitudes towards mental health in an urban Pakistani community in the United Kingdom.

The aim of this study was to investigate the attitudes of Pakistani families living in an urban area of the United Kingdom, towards mental health issues, to identify the emic models used and compare them with the etic model, predominant in Western medicine. This would allow the exploration of some of the inconsistencies in the research literature relating to the incidence of mental illness in this cultural group. The second aim was to explore the needs of this community, particularly women, in relation to mental health services. Due to problems gaining access to females on their own, interviews were held with family groups. Findings suggested that there were differences in the models of mental illness being employed with greater somatisation of symptoms in the Pakistani group and an emphasis on aggressive behaviour as a significant symptom. Treatment expectations also varied with some emphasis on traditional Pakistani treatments such as Faith healers and Hakims as well as General Practitioners and hospital treatments. Language difficulties, religious and cultural practices were also identified as barriers to female treatment in particular. Recommendations were made for improved training for interpreters and more emphasis on cultural factors and emic models of mental illness as part of medical training.

Adult↗
PubMed2000

Surgical voice restoration following ablative surgery for laryngeal and hypopharyngeal carcinoma.

Surgical voice restoration is an important part of functional rehabilitation of patients following ablative surgery for laryngeal and hypopharyngeal carcinoma. The aim of this retrospective study was to assess the functional status with regard to speech of a cohort of 100 patients (age ranged 34-84 years), who underwent laryngectomy and laryngopharyngectomy over a 10-year period (1989-1999). Ninety-two patients consented to surgical voice restoration. Primary tracheoesophageal punctures were performed in 70 and secondary punctures in 22 (mainly after jejunal flap reconstruction). Nine patients were excluded from this analysis (seven patients died prior to assessment, one had the prosthesis removed at her request and one patient had insufficient follow-up). Tracheoesophageal speech was assessed in the remaining 83 patients using a rating scale measuring the number of syllables per breath, use of voice and intelligibility by non-professional listeners. Currently, Provox 2 valves are being used in the majority of patients. Overall tracheoesophageal speech results were good in 45/83 (54.2 per cent), average in 22/83 (26.5 per cent) and poor in 15/83 (18 per cent). One patient could not develop tracheoesophageal speech. The majority of laryngectomy patients had good speech but in patients who had complex reconstructions tracheoesophageal speech was mostly rated as average. Average to good speech in more than two-thirds of the cohort of patients show that surgical voice restoration is a highly successful and valuable technique to restore speech functions after ablative surgery for laryngeal and hypopharyngeal carcinoma.

Adult↗
PubMed2000

Bryostatin 1-induced modulation of nucleoside transporters and 2-chlorodeoxyadenosine influx in WSU-CLL cells.

WSU-CLL cells, a fludarabine resistant B-cell chronic lymphocytic leukemia cell line, has been shown to exhibit enhanced sensitivity to 2-chlorodeoxyadenosine (2-CdA) following 48-72 h exposure to bryostatin 1. For 2-CdA to manifest its chemotherapeutic activity, it must first enter the cell through one of several specific nucleoside transporter systems. We present data to show that bryostatin 1-induced enhanced influx of 2-CdA is in part the result of bryostatin 1-induced modulation of nucleoside transporters in WSU-CLL cells. The bi-directional equilibrative NBMPR sensitive transporters in WSU-CLL cells were significantly down-regulated 90 min post-exposure to 1-200 nM bryostatin 1. This down-regulation was evident up to 144 h. In contrast, WSU-CLL cells exhibited a transient increase in Na+-dependent concentrative 2-CdA influx from 48 to 96 h after bryostatin 1 exposure which was evident for a longer duration than that accounted for by the increase in deocycytidine kinase activity. These data may, in part, explain the enhanced efficacy of 2-CdA seen in WSU-CLL cells following 48-72 h exposure to bryostatin 1. It may raise questions as to the importance of the bi-directional transporters in determining the resistance or sensitivity of CLL cells to 2-CdA or other nucleoside analogues.

Aged↗
PubMed2000

Sequential treatment of a resistant chronic lymphocytic leukemia patient with bryostatin 1 followed by 2-chlorodeoxyadenosine: case report.

Bryostatin 1 (Bryo-1) has been shown to differentiate chronic lymphocytic leukemia (CLL) cells to the hairy cell leukemia phenotype. The purine analogue 2-chlorodeoxyadenosine (2-CdA) exhibits enhanced activity in patients with hairy cell leukemia compared to those with CLL. Here we present a case report of a patient diagnosed with resistant CLL and treated sequentially with Bryo-1 followed by 2-CdA for three cycles. Molecular and biochemical parameters relative to the sequential treatment with these agents in vivo were comparable to those found in the WSU-CLL cell line in vitro (R. M. Mohammad et al., Clin. Cancer Res., 4: 445-453, 1998; R. M. Mohammad et al., Biol. Chem., 379: 1253-1261, 1998). There was a significant reduction of lymphocyte count from 37.1 x 10(3)/microl before the treatment to 3.4 x 10(3)/microl after treatment, and partial remission was achieved 2 months after the treatment. The percentage of morphologically differentiated lymphocytes was increased from 3% before treatment to 92% with the first cycle of Bryo-1. Similarly, expression of CD22, a marker of differentiation, increased from 38% to 97% and was maintained at a high level for the duration of the treatment. Analysis of the molecular markers of apoptosis in isolated peripheral blood lymphocytes revealed an increase in the Bax:Bcl-2 ratio after treatment with Bryo-1 in cycles 2 and 3, with associated poly(ADP-ribose) polymerase cleavage after Bryo-1 and 2-CdA treatment. The deoxycytidine kinase: cytosolic 5'-nucleotidase activity ratio increased modestly after Bryo-1 treatment, indicating increased sensitivity of the peripheral blood lymphocytes to 2-CdA. In summary, we found that sequential treatment with Bryo-1 and 2-CdA caused a significant reduction in peripheral blood lymphocytes (CLL cells) with simultaneous induction of differentiation and the initiation of the Bax: Bcl-2 apoptotic pathway.

5'-Nucleotidase↗
PubMed2000

Three-dimensional shade analysis: perspectives of color--Part II.

In addition to outlining the fundamental principles of color and its qualitative and quantitative measurement, the first part of this article explained the chemical, physical, physiological, and psychological realization of color. To complete this discussion, the second part focuses on numerous variables that affect shade determination in the clinical chromatic environment. A contemporary shade selection system is also presented, and its systematic approach and limitations when utilized in a laboratory or clinical environment are detailed.

Adult↗
PubMed1999

Identification of (CAG)(n) and (CGG)(n) repeat-binding proteins, CAGERs expressed in mature neurons of the mouse brain.

The trinucleotide repeats (CAG)(n) and (CGG)(n) have been shown to be expanded in responsible genes of several human hereditary neurological disorders. In studies of mice, we previously identified two homologous single-stranded (ss)(CAG) and ss(CGG) repeat-binding proteins, CAGER-1 (44 kDa) and CAGER-2 (40 kDa) (CAG-element-recognizing proteins). The specific binding activities of these proteins were predominantly detected in the mouse brain. We have isolated the cDNAs encoding CAGER-1 and CAGER-2 and found that they were identical to previously reported cDNAs for Puralpha and Purbeta, respectively. Puralpha of 28 kDa was previously identified as a replication-origin-binding protein that is ubiquitously expressed in proliferating cells. We show that the transcripts of CAGERs increase after birth and are detected at high levels in the adult mouse brain but at very low or virtually undetectable levels in other mouse tissues. Biochemical properties and molecular weights are different between CAGERs and Puralpha/beta. Immunostaining with specific antibodies against CAGERs indicates that CAGERs in the mouse brain reside in nonproliferating neurons but not in proliferating glia. We conclude that CAGERs and Puralpha/beta are unrelated proteins, and CAGERs are neuronal single-stranded sequence-binding proteins in the mouse brain. Misassignment of cDNAs is described.

Age Factors↗