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Biomedical subjects

K A Khan

Publications and source records attributed to K A Khan.

At least 19 recordsLinked to original sources
PubMed2006

Viral anti-inflammatory reagents: the potential for treatment of arthritic and vasculitic disorders.

Inflammatory and immune responses are inherent in the development of progressive arthritic or vasculitic disorders. Arthritis is frequently associated with accelerated forms of vasculitis; atherosclerosis being one form of accelerated vasculitis that blocks blood flow causing heart attacks and strokes. The arterial supply is central to maintaining normal articular function and acts as a conduit for inflammatory (innate) and immune (antigen dependent) cell trafficking in joints. The vasculature in some cases can become inflamed in the disease process. While treatment of severely debilitating arthritic disorders has improved, some current treatments are limited to reducing symptoms while others act as disease modifying drugs (DMARDs), but may have limited success. Many current treatments also have reported adverse side effects. Vasculitic disorders are similarly debilitating with high associated morbidity and mortality and current therapy for these disorders is only partially successful. Immune-modifying agents, which alter vascular inflammation, thus have potential for application in rheumatologic diseases. Viral immune modulating proteins reduce early arterial inflammatory responses with associated reductions in atherosclerotic plaque development and transplant rejection in a wide range of animal models. A clinical trial utilizing one such viral reagent, a secreted myxomaviral serpin, is currently in progress, assessing treatment of acute coronary syndrome, a vascular syndrome with marked up-regulation of systemic inflammatory responses. In this review we examine viral anti-inflammatory proteins as potential therapeutic reagents for arthritic and vasculopathic disorders.

Animals↗
PubMed2004

Cellular automata and its advances to drug therapy for HIV infection.

This paper gives an over view of the use of cellular automata (CA) model of drug therapy for HIV infection. Nonuniform CA is employed to simulate drug treatment of HIV infection, where each computational domain may contain different CA rules, in contrast to normal uniform CA models. Ordinary (or partial) differential equation models are insufficient to describe the two extreme time scales involved in HIV infection (days and decades), as well as the implicit spatial heterogeneity. Zorzenon and Coutinho [Phy Rev Lett, 16 (2001) 1] reported a cellular automata approach to simulate three-phase patterns of human immunodeficiency virus (HIV) infection consisting of primary response, clinical latency and onset of acquired immunodeficiency syndrome (AIDS). But here we present a related model, based on non-uniform CA to study the dynamics of drug therapy of HIV infection. The main aim in this model is to simulate the four phases (acute, chronic, drug treatment responds and onset of AIDS). The results shown here indicate that both simulations (with and without treatments) evolve to the relatively same steady state (characteristics of Wolfram's class II behavior). Different kinds of drug therapies can also be simulated in this model, which can be found useful for developing a proper drug therapy.

Anti-HIV Agents↗
PubMed2001

Surface-reconstruction-switched adsorbate photofragmentation dynamics.

Energy-resolved angular distributions of neutral fragments ejected during photoinduced electron transfer reaction of CH3Br on GaAs(100) exhibit three distinct methyl-radical ejection channels. These undergo marked changes when the termination is switched from the Ga-rich c(8 x 2) to the As-rich c(2 x 8). Our observations are consistent with a strong adsorption-site dependence of the dynamics.

Journal Article↗
PubMed2000

Hepatitis B vaccination among health care workers and students of a medical college.

OBJECTIVE: To study the vaccination status against Hepatitis B among health care workers and students of a medical school. MATERIALS AND METHODS: It is a descriptive study done at Allama Iqbal Medical College, Lahore. The participants comprised of 206 health care workers of various categories and 327 medical students. The main outcome measure was vaccination status and reasons for non-vaccination. RESULTS: Only 49% health care workers and 42.20% medical students were vaccinated. The main reasons for non-vaccination (47.7%) among health care workers was the high cost of vaccination, while the most often cited reason (33.7%) among medical student was the belief that they were not at risk. This belief was also prevalent among nurses (36.4%), laboratory workers (38.6%) and paramedics (33.2%). CONCLUSION: In a low-income country like Pakistan the health institutions should bear the cost for vaccinating their staff. Efforts should also be made to impart appropriate health education regarding hepatitis B infection.

Adult↗
PubMed1999

Development and evaluation of a multiple-unit oral sustained release dosage form for S(+)-ibuprofen: preparation and release kinetics.

Mini-matrix tablets containing S(+)-ibuprofen have been prepared by the wet granulation method. The hydrophilic matrix was formed with either xanthan gum, karaya gum or hydroxymethylcellulose (HPMC) together with a choice of additives from lactose, Encompress(R), Avicel(R) PH101, talc and Lubritab(R). Multiple unit dosage forms (MUDFs) were subsequently obtained by encapsulating the mini-matrix tablets into hard gelatin capsules. Preparation, in vitro release profiles and release kinetics are presented.

Capsules↗
PubMed1999

Silent myocardial ischemia and cardiac autonomic neuropathy in diabetics.

OBJECTIVE: To evaluate the association of silent myocardial ischemia (SMI) with cardiac autonomic neuropathy in asymptomatic diabetic patients. MATERIAL AND METHODS: Two hundred asymptomatic patients of diabetes mellitus were assessed for evidence of cardiac autonomic neuropathy. Of these, 30 (15 males, 15 females; mean age 44.7 +/- 8.8 years) were found to have cardiac autonomic neuropathy. Thirty (30) age and sex matched diabetic patients (mean age 42.4 +/- 7.6 years) who had no evidence autonomic neuropathy were included in the study as control group. Both the groups of patients were evaluated for SMI by 24 hour ambulatory electrocardiographic (ECG) monitoring. RESULTS: Incidence of SMI was significantly higher in patients with autonomic neuropathy 12/30 (40%) compared to those without 3/30 (10%) p < 0.001. Duration of diabetes was more (13 +/- 1.59 years) in patients with autonomic neuropathy compared to the control group (8.66 +/- 1.55 years) p < 0.001. Serum cholesterol and triglyceride levels were significantly higher in patients with autonomic neuropathy in comparison to control group < 0.05 and < 0.01, respectively. There was no difference in the pattern of SMI in the two groups (p = N.S). CONCLUSION: Cardiac autonomic neuropathy predisposes patients with diabetes mellitus to SMI. Twenty four hour ambulatory ECG monitoring provides useful diagnostic information in early detection and evaluation of SMI in asymptomatic diabetic patients.

Adult↗
PubMed1998

Relationship between swelling, erosion and drug release in hydrophillic natural gum mini-matrix formulations.

The swelling, erosion and solvent front penetration properties of mini-matrices containing xanthan (X), locust bean (LB) and karaya (K) gums were examined, analysed and related to the overall in vitro release kinetics of diclofenac sodium, used as a model drug. Mini-matrices were produced with drug:gum ratios of 1:1 as well as formulations of drug and X in combinations of 2:1, 2:3 and 1:2. The rank order of decreasing swelling index (SI) in both axial and radial dimensions was X?K?LB and each gum showed almost Fickian swelling behaviour. The solvent front penetration rates were consistent with the rates of swelling. However, the order of decreasing drug release and erosion rates was LB>X>K and all formulations demonstrated anomalous (non-Fickian) drug release kinetics. Therefore Fickian drug diffusion and polymer erosion were both occurring simultaneously. The dominant mechanism depended on the nature and content of the gum, as well as the stage in the dissolution time period. There was a loss of matrix integrity in formulations containing a high drug:gum ratio.

Diclofenac↗
PubMed1998

Comparative mutagenic and genotoxic effects of three antimalarial drugs, chloroquine, primaquine and amodiaquine.

Comparative mutagenic and genotoxic effects of three antimalarial drugs, chloroquine, primaquine and amodiaquine, were assessed in the Ames mutagenicity assay (in strains TA97a, TA100, TA102 and TA104) and in vivo sister chromatid exchange (SCE) and chromosome aberration (CA) assays in bone marrow cells of mice. These are the most commonly used antimalarial drugs available at present throughout the world. The results of the bacterial mutagenicity assays showed a very weak mutagenic effect of all three drugs in Salmonella strains TA97a and TA100 both with and without S9 mix and in TA104 only with S9 mix. The results of the in vivo SCE and CA assays indicate that these three drugs are genotoxic in bone marrow cells of mice.

Amodiaquine↗
PubMed1997

Comparative mutagenic and genotoxic effects of three propionic acid derivatives ibuprofen, ketoprofen and naproxen.

The mutagenicity of three propionic acid derivatives, namely ibuprofen, ketoprofen and naproxen, was tested in the Ames mutagenicity assay (in strains TA97a, TA100 and TA102) and in vivo genotoxicity was tested by sister chromatid exchange (SCE) in bone marrow cells of mice. These are the anti-inflammatory drugs frequently used in different parts of the world. Mutagenicity results showed no mutagenic effects in strains TA97a, TA100 and TA102 for all three drugs. Results of in vivo SCE assays indicate that these three drugs are weakly genoxic in bone marrow cells of mice. This is the first report of the Ames mutagenicity assay for ketoprofen and in vivo SCE assay for three drugs.

Animals↗
PubMed1997

Acetates and benzoates of alkyl catechols and evaluation of their antibacterial activity.

Potential biologically active alkyl catechol esters were prepared and their antibacterial activity was determined against 12 Gram-positive and 16 Gram-negative bacteria. Esterification (acetylation and benzoylation) of mono-, di- and tetra- substituted alkyl catechols afforded the di-acetyl and di-benzoyl derivatives in each case. In the primary screening it was observed that the substitution of hydroxyl group in alkyl catechol with an acyl group generally resulted in a decrease of antibacterial activity. A number of acetyl and benzoyl derivatives inhibited the growth of Salmonella typhi. In case of Gram-positive bacteria only di-O-benzoyl-3,5,6,-tetra-(3-hexyl) catechol (26) showed a significant activity.

Journal Article↗
PubMed1997

Comparative study of 18 gauge and 20 gauge intravenous catheters during transcranial Doppler ultrasonography with saline solution contrast.

A formal technical protocol has not been established for transcranial Doppler ultrasonography in the detection of venous to arterial shunts; techniques have been adapted from contrast echocardiography. We evaluated the effect of different diameter indwelling intravenous catheters on the detection of right-to-left shunts by transcranial Doppler ultrasonography. Fifteen patients underwent transcranial Doppler sonographic evaluation with saline solution contrast using both 18 gauge and 20 gauge indwelling intravenous catheters. The larger bore intravenous catheter delivered a greater number of signals in a shorter time to the insonated middle cerebral artery. We recommend that a standardized method for transcranial Doppler sonographic contrast studies include an 18 gauge intravenous catheter.

Adult↗
PubMed1996

Comparative genotoxicity of six salicylic acid derivatives in bone marrow cells of mice.

In vivo sister chromatid exchange (SCE) and chromosome aberrations (CA) were carried out for six salicylic acid derivatives in bone marrow cells of mice. Six salicylic acid derivatives, namely acetyl salicylic acid (aspirin), salicylic acid, salicylamide, sodium salicylate, diflunisal and niclosamide, were used for these experiments. Drugs were administered both intraperitoneally (i.p.) and orally by gavage. Out of these six salicylic acid derivatives tested, only diflunisal and niclosamide showed genotoxicity as measured by both SCE and CA assays. Acetyl salicylic acid and sodium salicylate showed weak genotoxicity as measured by SCE and CA, respectively, only at the highest dose tested.

Administration, Oral↗
PubMed1996

Transcranial Doppler ultrasonography in the detection of venous to arterial shunting in acute stroke and transient ischaemic attacks.

OBJECTIVES: To prospectively evaluate the prevalence of venous to arterial shunting in patients with acute stroke and transient ischaemic attacks (TIAs) using transcranial Doppler ultrasonography (TCD) with saline contrast. METHODS: A consecutive series of patients with stroke or TIA underwent contrast TCD. Patients were subsequently divided into groups according to causative factors for stroke or TIA. The prevalence of right to left shunt was assessed within these groups. RESULTS: A total of 210 patients underwent contrast TCD. A right to left shunt was detected in 28.6% of patients (60 of 210). Among the patients with cryptogenic stroke or TIA, 37.1% (43 of 116) had a positive contrast TCD whereas only 18% (17 of 94) with another identifiable cause had a positive test (P = 0.0024). When age was used to further classify those patients with cryptogenic stroke, TCD was positive in 59.3% patients (16 of 27) of < or = 50 years of age versus 30.3% of patients (27 of 89) > 50 years of age (P = 0.0058). CONCLUSIONS: There was a significantly higher prevalence of venous to arterial shunting in patients with stroke or TIA of undetermined cause than in stroke patients with identifiable aetiologies, as detected by contrast TCD. The prevalence of a venous to arterial shunt was significantly higher in the younger group with cryptogenic stroke. Saline contrast TCD is a relatively non-invasive bedside procedure useful in the detection of venous to arterial shunting.

Acute Disease↗
PubMed1996

A randomized double-blind comparative study of terbinafine for 1, 2 and 4 weeks in tinea capitis.

We report a randomized, double-blind study, comparing the relative efficacy and tolerability of oral terbinafine, given for 1, 2 or 4 weeks, in tinea capitis. Of 161 evaluable patients, 53 were treated with terbinafine for 1 week, 51 for 2 weeks and 57 for 4 weeks. Isolated pathogens included Trichophyton violaceum (71.5%), T. tonsurans (14.9%), T. verrucosum (4.3%), Microsporum audouinii (4.3%), M. canis (2.5%), T. schoenleinii (1.9%) and T. mentagrophytes (0.6%). The final evaluation, at 12 weeks, showed cure rates of 73.6, 80.4 and 85.9%, in the respective groups. The adverse effects noted, were not drug related. In our opinion, terbinafine given for 1, 2 or 4 weeks, is equally effective for most cases of tinea capitis.

Adolescent↗
PubMed1996

In vitro studies of the loss of antibacterial activity of oxytetracycline in presence of Ca(II) or Mg(II) ions.

The results of a comparative study, which evaluated the in vitro effect on the antibacterial activity of oxytetracycline (OTC, CAS 79-57-2) in presence of Ca(II)/Mg(II) ions suggest that susceptibility of Staphylococcus aureus, Bacillus pumilis and Bacillus subtilis to OTC is reduced in presence of Ca(II)/Mg(II) ions. As the ratio of concentration of Ca(II)/Mg(II) to OTC was increased, antibacterial activity of OTC declined. In addition to the difference observed between the antibacterial effect of pure OTC and its Ca(II)/Mg(II) complexes, it was found that decline in antibacterial activity is greater for Mg(II)-OTC complex than Ca(II)-OTC complex for the same concentration of Ca(II)/Mg(II) ions.

Anti-Bacterial Agents↗