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Biomedical subjects

Z Khan

Publications and source records attributed to Z Khan.

At least 91 records · Page 5Linked to original sources
PubMed1991

Bilirubin conjugates produced by human, dog, and rat hepatocytes transplanted into athymic Gunn rats.

We developed a new hybrid mutant rat (athymic Gunn hybrid strain) that does not form and excrete conjugated bilirubin into bile and accepts xenografts because of T-lymphocyte deficiency. Cryopreserved isolated normal human, dog, or rat liver cells attached to collagen-coated microcarriers were transplanted into the athymic Gunn hybrid rats. Transplantation of human or rat liver cells resulted in biliary excretion of bilirubin conjugates predominantly as glucuronides, whereas isolated dog liver cells likewise transplanted resulted in the excretion of 40% to 50% of the conjugates as a glucoside-glucuronide diconjugate. The biliary bilirubin conjugates of the transplanted athymic Gunn hybrid rats paralleled those of the donor species. The data indicate that the types of bilirubin conjugates excreted by each species are determined by intrinsic properties of the respective hepatocytes rather than nutritional or other environmental factors. The findings also show that conjugation of bilirubin after liver cell transplantation results from functioning of the engrafted cells rather than activation of endogenous uridine diphosphatelucuronosyltransferase activity of the host.

Animals↗
PubMed1990

The bond strength of a visible light-cured reline resin to acrylic resin denture base material.

The introduction of Triad visible light-cured denture resin has led to several applications. Among them is direct intraoral relining of complete and partial dentures. This study investigated the bonding characteristics of Triad reline resin to four commonly used heat-cured denture base resins. The shear and tensile bond strengths of Triad resin and four denture base resins were determined and compared with intact tensile strengths. The findings of this study indicate that the bond strength of Triad resin to denture base resin is sufficiently high to suggest its clinical applicability.

Acrylic Resins↗
PubMed1990

Analysis of voiding disorders in patients with cerebrovascular accidents.

Urodynamic evaluation was undertaken in 33 patients (15 males and 18 females, age range 48-90 years) with voiding problems following cerebrovascular accidents. In the majority of these patients (26) cystometry revealed involuntary contractions of the bladder. The critical volume for involuntary bladder contractions was approximately 200 mL. The majority of patients with cerebral cortex and/or internal capsule lesions had uninhibited relaxation of the sphincter during involuntary bladder contractions, while all of the patients with lesions only in the basal ganglia or thalamus had normal sphincter function. The remaining 7 patients had poor bladder contractions. Correlation of bladder dysfunction with the area of brain injury was not conclusive, but was suggestive of directions to be taken in future research.

Aged↗
PubMed1989

Adhesion characteristics of visible light-cured denture base material bonded to resilient lining materials.

This investigation compared the adhesion of resilient lining materials to Triad visible light-cured denture base material. The liners used were Tru-Soft, Molloplast-B, and Esscheem. Cylindrical samples were made from Triad VLC material and were sectioned to produce a flat bonding surface, which was roughened and treated with Triad bonding agent. Resilient liners 3 mm thick were processed according to the manufacturer's recommendations and samples were stored at 37 degrees +/- 1 degree C in distilled water for 48 hours and 30 days. Tensile bond strength was determined by using an Instron Universal testing machine for the three resilient liners.

Acrylic Resins↗
PubMed1989

Shoulder preparations for collarless metal ceramic crowns: hand-planning as opposed to rotary instrumentation.

This study was undertaken to determine whether hand-planning the gingival facial floor improved the overall fit and marginal adaptation of a collarless metal ceramic crown. An extracted central incisor was prepared conventionally. Separate impressions were made of the tooth with custom trays and poured in stone. Crowns were constructed and cemented with silicone impression material as the luting agent. The silicone film was captured in stone and sectioned. Film thickness was measured at six points on the buccal and lingual surfaces. The tooth was then modified at the gingival floor by hand-planning the margin to a smooth, flat finish, and the above procedures repeated. It was found that the fit of crowns as measured by the cement film thickness was significantly better (p less than 0.05) at the facial margin, facial, lingual incisal, and lingual surfaces for the hand-planned margins.

Crowns↗
PubMed1989

Urinary incontinence in female Parkinson disease patients. Pitfalls of diagnosis.

There are many causes of urinary incontinence in the female, with stress incontinence reported as the most common. However, a high incidence of detrusor instability has been described in incontinent patients with Parkinson disease. To assess this further, urodynamic studies were performed on 17 female patients with Parkinson disease and complaints of urinary dysfunction. Detrusor instability was demonstrated in the majority of the patients (70.6%). Of the 8 patients with specific symptoms of stress incontinence, 2 were found to have a stable bladder, 3 had a hyporeflexic bladder, and 3 had detrusor instability. Surgical therapy may not be appropriate for all patients in this group. Since it is difficult to determine the causation of urinary incontinence on the basis of symptoms alone, urodynamic studies can be helpful in the evaluation of incontinent patients. This is especially important in female patients with Parkinson disease who may have detrusor instability alone or in addition to anatomic stress incontinence.

Aged↗
PubMed1989

Urinary incontinence after transurethral resection of prostate in myasthenia gravis patients.

An unusually high incidence of urinary incontinence following transurethral resection of the prostate has been reported in patients with myasthenia gravis who were operated on for prostatism. It has been documented that this may be due to the vulnerability of the external sphincter to the electrothermal changes during transurethral resection of the prostate. In the case we studied, neuropathic changes were observed in the external sphincter; thus transvesical prostatectomy was performed instead, and no compromise of continence occurred.

Aged↗
PubMed1988

Urinary incontinence during orgasm.

Urinary incontinence occurring during orgasm in women is an infrequently volunteered symptom. We studied 3 such patients to understand the mechanism behind such leakage. Urodynamic studies were performed prior to and during orgasm. It was found that during orgasm, there was involuntary bladder contraction with simultaneous urethral relaxation, resulting in leakage. Similar studies performed prior to orgasm did not reveal any involuntary bladder contraction. We believe that incontinence during orgasm is multifactorial: the most important causes are sphincter incompetence, neuropathic hyperreflexic bladder, and non-neuropathic idiopathic bladder instability.

Adult↗
PubMed1988

Diagnosis and grading of outflow obstruction.

Urodynamic data from 66 male patients with obstruction due to benign prostatic hyperplasia were analyzed. Criteria for grading the severity of outflow obstruction based on uroflowmetry, post void residual urine, maximum bladder contraction (Pmax), and pressure during voiding (Pvoid) were developed. In selected cases, voiding cystourethrography also may be needed. These criteria help determine the need for prostatectomy. Unnecessary prostatectomies can then be avoided and can lead to significant reduction in mortality, morbidity, and health care expenses.

Adult↗
PubMed1988

Bursting strength in CO2 laser-assisted microvascular anastomoses.

Iliac artery end-to-end anastomoses were performed in 42 Sprague-Dawley rats, divided into seven groups, to determine the welding effects of CO2 laser radiation in microvascular anastomoses. Conventional suture techniques were performed on right iliac arteries, and left iliac arteries were anastomosed with a laser-assisted technique. Bursting strength and diameters of the anastomotic sites were measured at different intervals (from one day to five weeks) post surgery. The anastomotic patency rate was 100 percent in both groups, and the aneurysm rate was only 2 percent in the laser group. Bursting strength was low at one and three days post surgery in both groups; then, it increased gradually until both groups could withstand higher than physiologic pressures. Results of high patency rates, low aneurysm formation, and the ability to withstand pressures higher than physiologic, suggest that the laser-assisted anastomotic technique can play an important role in microvascular surgery.

Anastomosis, Surgical↗