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Biomedical subjects

M Amin

Publications and source records attributed to M Amin.

At least 91 records · Page 5Linked to original sources
PubMed1990

Electrophysiological responses of the housefly, Musca domestica nebula (Fr), taste receptors to KCl.

This paper aims at studying the response of the housefly labellar chemoreceptor to stimulation by KCl. These studies are limited to testing various concentrations of KCl solutions (0.005-1 M), using the electrophysiological "tip recording" method and examining the various spike characteristics such as threshold, phasic and tonic response, spike amplitudes, frequency and adaptation; for the anion, cation and water receptors. The large, medium and small hairs all respond to salt. The frontal large, medium and small hairs show a higher frequency response to equimolar KCl than the distal hairs. There is a bilateral symmetry in response pattern. The results are compared with the reported work on Phormia and Calliphora species. The Biedler's hypothesis is also tested for the salt receptors of Musca.

Animals↗
PubMed1989

Terminal loop cutaneous ureterostomy in cadaveric kidney transplantation.

The presence of a nonfunctional bladder is a common finding in some patients with end-stage renal disease in whom transplantation is a proposed option. Over the last 20 years, we have performed six terminal loop cutaneous ureterostomies for urinary drainage during kidney transplantation. Neurogenic bladder in five patients and exstrophy in one patient prohibited use of the bladder. Four long-term graft survivors (19 months and 4, 10, and 20 years) experienced no short-term problems with the procedure, but two episodes of pyelonephritis have occurred. In our patients no graft dysfunction or loss could be attributed to infection, and no stomal stenosis or revision has occurred. We conclude that terminal loop cutaneous ureterostomy is feasible using normal-caliber ureters, and is a safe, effective means of urinary drainage during kidney transplantation when the bladder is not available. It also eliminates the necessity of preparatory bowel surgery that has its attendant risk of contamination in an immunocompromised patient.

Adult↗
PubMed1989

Complications of whole bladder dihematoporphyrin ether photodynamic therapy.

Photodynamic therapy with dihematoporphyrin ether was used to treat superficial bladder tumors in 7 patients with a followup of at least 1 year. Each patient received treatment to the whole bladder and those with papillary lesions received additional focal treatment. At 3 months 4 of the 5 patients with papillary tumors (stages Ta and T1) and 1 of the 2 with diffuse carcinoma in situ (Tis) were free of disease. However, at 1 year only 3 patients remained free of disease. Of 5 patients with an increase in irritative bladder symptoms 4 had a contracted bladder, hydroureteronephrosis and vesicoureteral reflux. Deep bladder biopsies showed replacement of smooth muscle by fibrous tissue. Six patients had mild to moderate skin phototoxicity. We conclude that although photodynamic therapy is an attractive and exciting method to treat cancer, its use with dihematoporphyrin ether in cases of bladder carcinoma can be associated with significant complications. The correct treatment parameters for safe, effective therapy are not known to date.

Adult↗
PubMed1989

Radical neck dissection: a 19-year experience.

A series of 394 radical neck dissections performed over the 17 year period 1969-1986 is presented. The shortest period of follow-up is two years. Of the major complications reviewed, wound breakdown was associated with T stage, prior radiotherapy and incision used but not with age or N stage. Cervical recurrence was associated with N stage, prior radiotherapy and surgical incision and inversely associated with age. Wound breakdown and recurrence were lowest in parotid primary tumours. Carotid artery rupture occurred in 17 patients (4.3 per cent), was fatal in all cases and was strongly associated with wound breakdown and previous radiotherapy. The importance of the choice of incision, clearance of the posterior belly of the digastric muscle and carotid artery protection are discussed.

Adolescent↗
PubMed1989

Skin-prick test preparations of Dermatophagoides pteronyssinus for prediction of a positive response to provocation testing.

Skin-prick testing (SPT) with allergen is widely used in the investigation of respiratory disease, yet its relationship to the results of provocation testing of the nose or bronchus remains obscure. We have studied this relationship by determining the concentration of Dermatophagoides pteronyssinus extract and the associated weal size which resulted in the lowest 'false positive' (FP) and highest 'true positive' (TP) rates when compared to the results of bronchial and nasal provocation testing. Subjects studied included those with both positive and negative bronchial or nasal provocation tests. For each of a series of concentrations of D. pteronyssinus extract, standardized in relation to content of Der pI antigen, receiver operating characteristic (ROC) curves of TP against FP rates were constructed. Optimal diagnostic concentrations for SPT were 0.112-1.122 x 10(6) IU of Der pI ml-1. However, at the lower end of this range the optimum weal areas for a positive test with the D. pteronyssinus extract were very small (less than 5 mm2). More appropriate concentrations for use in clinical practice were 0.56-1.122 x 10(6) IU Der pI ml-1 since at these concentrations more easily measurable weal areas of 5-10 mm2 (2.6-3.6 mm diameter) were almost equally predictive of a positive provocation test.

Airway Resistance↗
PubMed1989

Coupling of the enzymic activities of myosin ATPase and creatine kinase and its role in muscular contraction.

During muscular contraction the regeneration of ATP, catalysed by creatine kinase (CK), keeps pace with the hydrolysis of ATP by myosin ATPase posing the question of its regulatory mechanism. In the background of F-actin activation of heavy meromyosin (HMM) ATPase activity we have investigated in vitro the role of F-actin in regulating CK's activity in the absence and presence of HMM. For the coupled enzyme system we have also looked into the roles played by the individual reactants. F-actin has been found to appreciably increase CK's activity in the absence of HMM. While HMM alone inhibited CK's activity, there was a several fold increase when F-actin was also present. By a process of elimination we conclude that none of the reactants apart from H+ could be involved in regulating CK's activity in the coupled enzyme system. As no change in the pH of reaction mixture was observed during the reaction, we further conclude that the two enzymic reactions are coupled by proton transfer along F-actin. Implications of the findings for PCr-Cr shuttle and movements of ATP and ADP in sarcomere are discussed.

Actins↗
PubMed1989

Effect of extracellular pH and DNFB treatment on the mechanical performance of frog skeletal muscle.

isometric tension and maximum velocity of shortening of frog sartorious and biceps muscles were measured at varying pH and compared with the values obtained for muscles treated with DNFB. Both To and Vmax exhibited increase with increase in pH above neutral pH upto pH 9, and decreased as the pH was decreased up to 5. Muscle treated with DNFB at pH 7 showed about 30% decrement but these too improved at pH 9 to almost 105% and 130% respectively compared to untreated muscle at pH 7. Using the number of short duration tetanic contractions, which reduce To and Vmax by half, as an index for the onset of fatigue, high pH was found to have a positive effect in both normal and DNFB-treated muscle. Thus, the crucial factor for onset of fatigue is not a fall in ATP level but acidification and treatment with high pH Ringer's solution partially annuls the effect of acidosis, arising either naturally or from DNFB treatment. One additional role of creatine kinase activity to that of ATP regeneration is suggested to be the maintenance of neutral pH in the sarcoplasm.

Adenosine Triphosphate↗
PubMed1989

Simultaneous determination of prostaglandins (PG) E2, A2 and B2 and stability studies of PGE2 in pharmaceutical preparations by ion-pair reversed phase HPLC.

In previous reports a direct thin-layer chromatographic method (TLC) for the determination of prostaglandins (PG) E2, A2, B2 and F2 alpha and a High-Performance Liquid Chromatographic method (HPLC) for the determination of PGE2-, PGA2- and PGB2- descendants and for stability studies of PGE2-descendant in pharmaceutical preparations were described In this paper the described HPLC method and a newly developed technique based on ion-pair HPLC are given for the simultaneous determination of PGE2, PGA2 and PGB2 and for the stability studies of PGE2 in pharmaceutical preparations. The extraction of PG's from pharmaceutical preparations is performed in a fully automated, electronically controlled extraction apparatus within 3 minutes. Ion-pair reversed phase HPLC is performed on a column of LiChrosorb RP18 using either methanol-water-octan-1-sulfonic acid sodium salt (55 ml + 45 ml + 65 mg) or methanol-water-tetrabutylammoniumperchlorate (360 ml + 290 ml + 1.0 g) as eluent. HPLC separation can also be performed on a column of mu-Bondapack C18 using methanol-n-butanol-glacial acetic acid-water (350 ml + 45 ml + 5 ml + 400 ml) as solvent. The stability of PGE2 is investigated in pure substance, in ethanolic-aqueous solution, in absolute ethanolic solution and in freeze-dried ampoules. The examined preparations are stored at temperatures between 4 and 40 degrees C and are investigated periodically. The stability studies of PGE2 indicate that PGA2 and PGB2 are formed as degradation products of PGE2. The prediction of the stability studies of PGE2 indicate that this active drug is unstable in pure substance as well as in pharmaceutical preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗
PubMed1988

Carrot phytoalexin alters the membrane permeability of Candida albicans and multilamellar liposomes.

The biochemical basis for the antimicrobial effect of the carrot phytoalexin 6-methoxymellein (6-MM) was examined. At fungistatic concentrations 6-MM retarded the ability of Candida albicans to incorporate radioactive thymidine, uridine and leucine into biopolymers. When C. albicans was incubated with 6-MM, 260-nm-absorbing materials and 3H-labelled compounds leaked from the cells. The inhibitory effects of 6-MM on cell growth and membrane functions were, however, reduced as the concentration of divalent metal cations added to the medium was increased. 6-MM interacted with multilamellar liposomes constituted from phosphatidylcholine, cholesterol and dicetyl phosphate, or from phosphatidylcholine only, resulting in the release of glucose trapped in these liposomes. These results suggest that 6-MM exerts its toxic effects on susceptible cells as a result of its interaction with their membranes and disturbance of membrane-associated functions.

Candida albicans↗
PubMed1988

The aetiology of laryngocoele.

Dimensions and volumes of 200 hemilarynges were measured to establish the normal range of laryngeal air sac size in males and females. Large saccules reaching the upper border of the thyroid cartilage were unilateral in 23 and bilateral in 20. Saccular volume is significantly related to ventricular volume but not to age, sex or laryngeal size. Large bilateral saccules are common and, therefore, a likely underlying factor in laryngocoele. However, the unilaterality of the disease, its male predominance and its age distribution, suggest that local laryngeal pathologies are perhaps the determinant factor in the pathogenesis of the disease.

Adult↗
PubMed1988

Interferon in chronic active hepatitis B. Preliminary results.

Twenty patients with documented chronic active hepatitis B were randomized in equal numbers to either an alpha-2b interferon treatment group or a control group with no treatment. Patients in the first group received 5 IU interferon three times weekly by subcutaneous injection for 16 weeks. All 20 patients were HBeAg positive at the beginning. All 10 patients in the interferon-treated group lost their initial e antigen while only 2 patients in the control group turned HBeAg negative. Six patients in the treated group acquired HBe antibodies in comparison with two patients only in the untreated group. Other markers of suppression of viral replication as well as a 24-month follow-up are ongoing at the moment for final assessment of the value of interferon therapy in chronic active hepatitis B.

Adolescent↗
PubMed1988

Blunt urethral injury: results of initial management.

Fourteen men with blunt urethral disruption were treated between 1979-1985. Injuries most commonly resulted from motor-vehicle accidents, as pedestrians or passengers. All patients had additional injuries, including pelvic fracture (13), extremity fractures (10), central nervous system (5), bladder (5) and rectal injury (3); the average injury severity score was 30. Pelvic fracture patterns included ten patients with a crushed pelvis, two with single anterior pelvic ring fractures and one with a double vertical fracture. Blood at the urethral meatus was noted in only five patients, gross hematuria without metal blood in another three, and a displaced prostate on rectal exam was found in 10 cases. All patients had a suprapubic cystostomy for management of the urethral injury. Thirteen of 14 patients survived (93%). The major complication was perineal sepsis. Based on this experience, it is concluded that: 1) the classical findings of urethral injury are not found consistently, 2) certain pelvic fracture patterns, particularly disruption of the anterior pelvic ring, are frequently associated with urethral injury and 3) aggressive and appropriate management of hemorrhage, pelvic fracture and concomitant injuries is important to minimize mortality.

Adult↗