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Biomedical subjects

R A Khan

Publications and source records attributed to R A Khan.

At least 37 records · Page 2Linked to original sources
PubMed2001

Investigation of Uña De Gato I. 7-Deoxyloganic acid and 15N NMR spectroscopic studies on pentacyclic oxindole alkaloids from Uncaria tomentosa.

The C-8-(S) isomer of deoxyloganic acid (7-deoxyloganic acid), together with beta-sitosteryl glucoside, five known stereoisomeric pentacyclic oxindole alkaloids and the tetracyclic oxindole isorhyncophylline, were isolated from the inner bark of Uncaria tomentosa. Structures of the isolated compounds were based on 1H and 13C NMR data, mainly 2D NMR experiments, including 1H-13C HMBC and 1H-1H NOESY correlation. Furthermore, the hitherto unreported 15N chemical shifts of the isomeric oxindole alkaloids, using 1H-15N HMBC experiments, were utilized to facilitate their characterization. Uncarine D showed weak cytotoxic activity against SK-MEL, KB, BT-549 and SK-OV-3 cell lines with IC(50) values between 30 and 40 microg/ml, while uncarine C exhibited weak cytotoxicity only against ovarian carcinoma (IC(50) at 37 microg/ml).

Alkaloids↗
PubMed2001

Improved method for the determination of oxindole alkaloids in Uncaria tomentosa by high performance liquid chromatography.

This Paper describes an improved HPLC method for the determination of pentacyclic oxindole alkaloids in Uncaria tomentosa (Cat's Claw). Six of the isomeric compounds could be baseline separated at room temperature within less than 30 min by using 3 microm C-18 column material and a mobile phase consisting of 10 mM phosphate buffer at pH 7.0 and acetonitrile. At a wavelength of 245 nm all standard compounds could be detected at concentrations as low as 0.63 microg/ml. Different samples of U. tomentosa bark and market products containing Cat's Claw were extracted with a modified procedure ensuring the integrity of the alkaloids and analyzed successfully. The results indicated accuracy and consistency of the new method, and showed variations in the total alkaloid content in products from 0.156 to 0.962%.

Alkaloids↗
PubMed2001

Persistent synchronized oscillations in prolactin gene promoter activity in living pituitary cells.

PRL gene expression in the anterior pituitary gland responds rapidly to different hormonal signals. We have investigated the long-term timing of transcriptional activation from the PRL, GH, and cytomegalovirus promoters in response to different stimulus duration, using real-time imaging of luciferase expression in living stably transfected GH3 cells. Long-term stimulation of serum-starved cells with 50% serum induced a homogeneous rise in PRL promoter activity, with subsequent heterogeneous fluctuations in luciferase activity in individual cells. When cells were subjected to a 2-h pulse of 50% serum, followed by serum-free medium, there were long-term (approximately 50 h) synchronized, homogeneous oscillations in PRL promoter activity. This response was PRL-specific, because in GH3 cells expressing luciferase from the GH or cytomegalovirus promoters, a serum pulse elicited no oscillations in luciferase expression after an initial transient response to serum. The PRL promoter may therefore be a template for an unstable transcription complex subject to stochastic regulation, allowing an oscillatory transcriptional response to physiological signals. This suggests that precise timing and coordination of cell responses to different signal-duration may represent a novel mechanism for coordinating long-term dynamic changes in transcription in cell populations.

Blood Physiological Phenomena↗
PubMed2001

An observational study of 256 cases of vascular trauma in the north western province of Pakistan.

During the past 10 years Peshawar has dealt with increasing casualties with penetrating trauma inflicted by a wide variety of missiles. The aim of this study was to assess whether delay in arrival and mode of presentation affects the outcome of patients with penetrating vascular trauma. Prospective data were collected on 256 vascular injuries in 248 patients (median age, 29 years; range, 7-60 years) between January 1995 and June 1998. Early presentation (group A, 55 cases, < 12 h) was compared with late presentation (group B, 201 cases, > 12 h). The majority of injuries (93%) were caused by fire-arms. Arterial injuries accounted for 71% of the total, venous injuries accounted for 10% and 19% were mixed. The site of injury was the lower limb (61%), upper limb (32%), abdominal cavity (5%) and neck (2%). Patients presented with absent pulses (56%), haemorrhage (46%), false aneurysms (8%), A-V fistula (5%) and 11% presented with more than one sign. There were significantly more lower limb amputations in group A than group B (23% versus 5%; P < 0.05), with fractures having a positive association with lower limb amputations (odds ratio, 0.32; 95% CI, 0.13-0.94; P < 0.05). Group A had a higher mortality than group B (18% versus 7%; P < 0.05). This study shows that patients with vascular trauma can be managed successfully with clinical assessment alone. Patients with fractures were more likely to suffer eventually from lower limb loss. Due to self-selection, arrival at the hospital less than 12 h after sustaining vascular injury was associated with a higher mortality than those presenting after 12 h.

Adolescent↗
PubMed2001

A pilot study: asymptomatic hyperlipoproteinemias in undergraduate university students.

Young adults may suffer hyperlipoproteinemias, which may be asymptomatic. This pilot study was conducted to screen out hyperproteinemias in undergraduate university students. 30 asymptomatic students were randomly selected and preliminary examined: serum cholesterol, triglycerides, LDL and HDL were determined, 10.35% of the students had high cholesterol and triglycerides levels. It is an important finding offering a mass screening program in our undergraduate university students.

Journal Article↗
PubMed2000

Decontamination of winter flounder (Pleuronectes americanus) following chronic exposure to effluent from a pulp and paper mill.

A study was conducted to determine the influence of decontamination on winter flounder living downstream from a pulp and paper mill. The fish and controls were held 8-26 weeks under contaminant-free conditions in aquaria supplied with ambient sea water. Groups of flounder, for comparison, were also sampled near the paper mill at the time of or following autopsy. No differences were apparent in length/organ-weight relationships between depurated and control groups after 26 weeks at 0-6 degrees C, but condition factor, gonadal and hepatosomatic indices, coincident with elevated levels of detoxifying enzymes, differed from field-derived samples. Pathological changes, including hemosiderin deposits in the liver and spleen, decreased, whereas pericholangitis and clear cell foci were apparent in the depurated fish and in the field samples. In two additional groups decontaminated for 8-16 weeks at 6-16 degrees C, there was no evidence of pericholangitis, but hemosiderin deposits persisted and an increase of fibrosis and clear cell foci occurred in contrast to the field group. These results suggest that some tissue repair in the liver transpired primarily during summer while other lesions, such as preneoplastic clear cell foci, which were probably induced prior to depuration, increased, but hemosiderin concentration remained unchanged. The latter observation is consistent with previous studies that suggest that hemosiderin concentration is not seasonally but age influenced.

Animals↗
PubMed2000

Reduction of radiation exposure to patients in the follow-up of shockwave lithotripsy.

OBJECTIVES: To assess, in patients undergoing extracorporeal shock wave lithotripsy (ESWL), if a policy of using unilateral X-rays of the kidney, ureter and bladder (hemi-KUB) whenever possible and appropriate during diagnosis and follow-up, was successful in reducing the radiation exposure associated with ESWL. PATIENTS AND METHODS: Two groups of patients of statistically comparable size and demography were assessed retrospectively before and after the implementation of the policy. All had undergone ESWL for radio-opaque upper urinary tract stones and all were finally rendered stone-free. The number and type of all radiological procedures from initial diagnosis of the stone to documented stone-free status were recorded and the dose calculated. RESULTS: The appropriate use of hemi-KUB X-rays resulted in a significant mean reduction of radiation exposure after treatment of 2.28 mSv per patient (P<0.05). Furthermore, as expected, the radiation dose was clearly but not closely correlated with stone size (r = 0.419). CONCLUSIONS: The appropriate use of hemi-KUB X-rays during the follow-up after ESWL is a simple and effective way of significantly reducing the radiation exposure of such patients.

Adult↗
PubMed1997

Marinesco-Sjögren syndrome in a Bedouin family.

Marinesco-Sjögren syndrome is rarely reported in the Middle East. This is the 2nd report of Marinesco-Sjögren syndrome in an Arab family. The clinical features of 2 affected brothers are described. Electrophysiological studies of the 2 patients showed primarily myopathic changes, whereas sural nerve biopsy revealed segmental demyelination and axonal degeneration. The role of tissue biopsy and the relationship to different electrophysiological studies are discussed. Both patients were noticed to have abnormally short lateral 3 metatarsals, a feature not present in other healthy members of the family. We suggest that this feature should be considered part of the syndrome profile.

Abnormalities, Multiple↗
PubMed1997

Pharmacological evaluation of newly synthesized piperidinium derivatives for their analgesic activity.

Two chemically synthesized piperidinium derivatives i.e l-methyl-1-(3,4) dihydroxy phenacyl-4-hydroxy piperidinium chloride and 1-methyl-(4-p) methoxy phenacyl 4-hydroxy piperidinium bromide have been evaluated for their analgesic activity in intact albino mice by tail immersion method because of their structural similarity with opioids. Both the compounds were administered in the doses of 50 mg/kg. The results were compared with pethidine used as the reference drug. The control animal received only the vehicle. The present study suggested that both the compounds exhibit significant analgesic activity.

Journal Article↗
PubMed1997

A multidisciplinary approach using several biomarkers, including a parasite, as indicators of pollution: a case history from a paper mill in Newfoundland.

Several biomarkers are currently used to determine chronic exposure of fish to environmental contaminants. In studies to assess the effects of pulp mill effluent on winter flounder (Pleuronectes americanus), body and hepatosomatic indices (HSIs), histopathology, levels of hepatic detoxifying enzymes, mixed function oxygenases (MFO), muscle acetylcholinesterase (Ache) and selected parasite abundance were compared in samples taken near a paper mill (sulphite-bleaching) and a number of reference sites. Our studies revealed a number of significant (P < 0.05) differences between samples taken near the paper mill and reference sites. Flounder captured at two locations near the mill were greater in length and weight, had elevated HSIs and more lesions in the liver and spleen while an acanthocephalan, Echinorhynchus gadi, located in the digestive tract, was lower than at more distant sites. Activity of MFO and Ache were similar at most sites and might be a reflection of the fish's foraging behaviour and consequently intermingling of populations from different locations during summer. These results support the view that several biomarkers should be utilised when assessing the health of fish living in habitats degraded by pollutants.

Acanthocephala↗
PubMed1994

Preliminary screening of methanolic extracts of Celastrus paniculatus and Tecomella undulata for analgesic and anti-inflammatory activities.

Flowers of Celastrus paniculatus and whole plant of Tecomella undulata were extracted individually in absolute methanol. Using the hot water tail immersion test in mice and carrageenan induced pedal edema in rats, both extracts were tested for their oral analgesic and anti-inflammatory potentials. Results showed that C. paniculatus had both analgesic and anti-inflammatory activities, while T. undulata had only analgesic potential when compared with aspirin.

Analgesics↗