Search PubMed⌕ Search

Biomedical subjects

A Khan

Publications and source records attributed to A Khan.

At least 361 records · Page 20Linked to original sources
PubMed1994

Interobserver agreement using computed radiography in the adult intensive care unit.

RATIONALE AND OBJECTIVES: We determined whether computed radiographs in an adult intensive care unit produce greater agreement between readers in descriptions of radiologic findings and interval changes. METHODS: Fifty-six conventional radiographs and 56 computed radiographs were obtained on 28 patients. Computed and conventional radiographs were imaged simultaneously in a single exposure with the use of a sandwich cassette. The two sets of films per patient were taken less than 1 week apart. RESULTS: Four readers evaluated the chest films and judged interval changes with the use of standardized confidence scales. Overall exposure and film quality also were evaluated. Computed radiographs were rated better in overall quality. Tubes and lines were detected with comparable accuracy. Interobserver agreement in the evaluation of radiologic descriptors was generally greater with computed radiographs (intraclass correlation). No differences were noted in interobserver agreement in the judgment of interval changes. CONCLUSIONS: The diagnostic usefulness of computed radiography is comparable to conventional films in the intensive care unit. The higher interobserver agreement rate for radiologic descriptors with computed radiography is an added advantage of the system.

Adult↗
PubMed1994

Perceptions of parental and peer attachments by women with mood disorders.

The relationship between perceptions of parental and peer attachments at various ages and adult mood disorders was examined in 156 women classified as having bipolar disorder or unipolar depression or as nonpsychiatric controls. Nonpsychiatric controls reported a decreased attachment to their parents over time, but they also reported an increased closeness to their mothers in adulthood following a distant adolescence. Never hospitalized, moderately depressed subjects showed a similar trend toward decreased relatedness, but moderately depressed subjects did not report reestablishment of a close relationship with their mothers after adolescence. Severely depressed and bipolar subjects reported little attachment to their mother at all ages. Bipolar subjects also reported little connectedness to their fathers throughout their lifespan and severely depressed women felt less attached than nonpsychiatric controls to peers during development. None of the psychiatric groups reported difficulties with parental overcontrol.

Adult↗
PubMed1994

Dependency, self-criticism, and perceptions of socialization experiences.

This study explored the relationship of dependency and self-criticism to perceptions of socialization experiences using 132 bipolar, nonbipolar depressed, and nonpsychiatric control female subjects. After controlling for level of depression and diagnosis, dependency was related to a distant relationship with fathers during development and was marginally related to perceptions of increased parental attention and overindulgence. Self-criticism was related to perceptions of difficulties in the quality of affective bonds with fathers and peers during childhood and was related marginally to perceptions of increased paternal power and control during development. No unique socialization experiences were associated with high dependency and self-criticism jointly, but women with both dispositional tendencies were likely to be severely depressed.

Adult↗
PubMed1994

Use of polyacrylamide gels in a saline-filled tank to determine the linearity of the Sheffield Mark 1 electrical impedance tomography (EIT) system in measuring impedance disturbances.

Polyacrylamide gels have been assessed as a means of producing reliable small impedance changes for EIT studies in saline-filled tanks. Test rods could be made in about 10 min from a stock solution of acrylamide monomer and bis-acrylamide, ammonium persulphate and tetramethylethylaminediamine, completed with saline. Impedance increases of about 10%-200% were produced by varying the gel concentration. The method appears to be easy to use, inexpensive and is stable over time. Its use was illustrated by acquiring EIT images with a Sheffield Mark 1 system and a tank filled with 0.2% saline. Polythene or polyacrylamide rods of varying resistivities, 10% of the tank diameter wide, were placed in one of three positions. The magnitude of the impedance increase in EIT images varied linearly with the actual impedance change in the rods for increases up to 20%, but the blurring in images was similar when polythene rods were used. This suggests that the use of highly resistive test objects gives a reasonable indication of the blurring in EIT images acquired with the system used, but measurement of the magnitude of the impedance change is more likely to be accurate for changes of a few tens of per cent.

Acrylic Resins↗
PubMed1994

Dexamethasone-induced tumor lysis syndrome in high-grade non-Hodgkin's lymphoma.

Tumor lysis syndrome is a catastrophic complication of the treatment of certain neoplasms. It most commonly occurs in association with hematologic malignancies and manifests a few hours to a few days after initiation of specific chemotherapy. It has rarely been encountered as a complication of steroid therapy only. Tumor lysis syndrome is a potentially fatal condition if it is not recognized promptly and managed aggressively. We report on a patient with high-grade non-Hodgkin's lymphoma who developed severe metabolic acidosis, hyperkalemia, hyperphosphatemia, and hypocalcemia within 2 days of starting corticosteroid therapy. He was managed with intravenous fluids, bicarbonate infusion, calcium gluconate, and 25% dextrose with insulin. He did not respond to these measures and died within a few hours of the diagnosis of tumor lysis syndrome. Increasing awareness of this complication and proper prophylactic measures are necessary to improve the outcome.

Adult↗
PubMed1994

Role of hns in the virulence phenotype of pathogenic salmonellae.

A TnphoA-generated mutant C5060, attenuated for virulence, was derived from the mouse-virulent Salmonella typhimurium strain C5. This mutation, designated hns-112::TnphoA, harbours the transposon in the 3' end of hns, with the alkaline phosphatase open reading frame in the opposite orientation to that of hns. Bacterial strains harbouring hns-112::TnphoA were mucoid and had altered levels of DNA supercoiling, as monitored using pUC18 as a reporter plasmid. Transduction of hns-112::TnphoA into mouse virulent strains, including S. typhimurium SL1344 and Salmonella enteritidis Se795, resulted in attenuation. When an independent hns mutation, harbouring a kanamycin-resistance cassette inserted into the Kpnl site at base pair 237 of the hns gene, was introduced into S. typhimurium C5, the isolates were also attenuated. S. typhimurium C5 isolates harbouring the multicopy plasmid pGB651, which encodes the Escherichia coli hns gene, were partially attenuated in mice. Transductional analysis, using Tn10 insertions located close to the hns gene, showed that virulence could be restored in genetic crosses that eliminated the resident hns mutations. However, some hns+ transductants were still attenuated, suggesting that secondary attenuating lesions can accumulate in hns-deficient strains. These studies show that the hns locus plays a role in Salmonella virulence.

Animals↗
PubMed1994

Cerebrospinal fluid HIV-1 p24 antigen and culture: sensitivity and specificity for AIDS-dementia complex.

We prospectively evaluated 94 patients with AIDS-dementia complex (ADC) and a smaller group of 27 patients with other HIV-1 related neurological conditions to determine the usefulness of cerebrospinal fluid (CSF) p24 antigen and HIV-1 culture in the diagnosis of ADC. The presence of ADC correlated with detectable CSF p24, but not with a positive culture. However, only 54% of the patients with severe or end stage (stages 3 and 4) ADC had detectable CSF p24 and only 25% had a positive culture. Among those with detectable CSF p24, there was no discernible relationship between the severity of ADC and the amount of CSF p24. The diagnostic sensitivity of CSF p24 in ADC was 21% whereas the specificity was 98%. CSF HIV-1 culture had a sensitivity of 30% and a specificity of 80%. To address the possibility of binding of p24 in immune complexes, thereby escaping detection, an acid hydrolysis procedure was performed on the CSF and serum samples. This did not, however, make an appreciable difference in the detection rate of p24. To delineate whether the finding of cell free virus in the CSF was associated with ADC, CSF culture for HIV-1 was performed on both cell depleted and cell associated fractions. It was uncommon for CSF to be culture positive in only the cell free fraction and there was no relationship to the presence or severity of ADC.

AIDS Dementia Complex↗
PubMed1994

Bleomycin-induced fibrosis in pigs: evaluation with CT.

PURPOSE: To establish an animal model for use in evaluation of early morphologic changes of pulmonary fibrosis by means of precise correlation of findings at thin-section computed tomography (CT) and pathologic findings. MATERIALS AND METHODS: Bleomycin (1.0-2.5 U per kilogram of body weight) was delivered selectively into the left lower lobe bronchus via balloon catheter in five Yorkshire pigs. Sequential CT examinations were performed at regular intervals. The animals were killed at follow-up of 5 days to 4 weeks. At autopsy, the lungs were removed, inflated, fixed and dried, and subsequently sliced into sections that corresponded to the CT sections. The fixed lungs were examined with thin-section CT, radiography, and histologic studies. RESULTS: There was good correlation between pathologic findings at CT and specimen radiography. Histologic study revealed signs of pneumonitis and developing fibrosis. CONCLUSIONS: This disease model is suitable for radiologic and pathologic evaluation of interstitial fibrosis. CT was sensitive in detection of bleomycin-induced abnormalities.

Animals↗
PubMed1994

Effects of low-dose TRH on cognitive deficits in the ECT postictal state.

A low dose (0.5 mg) of thyrotropin-releasing hormone (TRH), a short-acting tripeptide with known analeptic properties, was administered to eight depressed patients 5 minutes after ECT session 3 or 4 in a double-blind, placebo-controlled crossover design. After TRH infusion the patients displayed selectively better performance on a battery of neuropsychological tests than they did after placebo infusion. Further exploration with pharmacological probes to mitigate ECT postictal cognitive deficits is warranted.

Adult↗
PubMed1994

Preoperative parathyroid localization: prospective evaluation of technetium 99m sestamibi.

The utility of preoperative parathyroid localization remains controversial. The gold standard for identification of abnormal parathyroid glands is exploration of the neck by an experienced surgeon. However, both for the experienced and less experienced surgeon, it may be desirable to localize the abnormality before surgery. Such a study would not only direct the surgeon to the site of the lesion but also would help reduce unnecessary dissection, the number of negative explorations, and operative anesthesia time. Unfortunately, currently used noninvasive techniques including ultrasonography, thallium-technetium subtraction, computed tomography scan, and magnetic resonance imaging have had only limited success (35% to 78%) in demonstrating abnormal parathyroid glands. Thirty patients with proven hyperparathyroidism were enrolled to compare a new imaging agent, technetium 99m sestamibi, as an alternative to thallium 201 for subtraction scintigraphy with technetium 99m pertechnetate. Only 14 of 30 patients operated on at George Washington University underwent an identical surgical approach (exploration of all four glands) and had complete preoperative calcium and parathormone levels, postoperative calcium levels, and total time of surgical procedures to formulate the basis of this report. The remaining 16 had their surgeries at other institutions. A surgical approach different from that used at George Washington University and unavailability of postoperative calcium levels and times of surgical procedures from these institutions necessitated deletion of these 16 patients from this report. Technetium 99m sestamibi-technetium 99m subtraction scans accurately localized the abnormal parathyroid gland in 13 of 14 patients, as compared with only 9 of 14 thallium 201-technetium 99m pertechnetate subtraction scans. These results support technetium 99m sestamibi scanning as the superior modality for preoperative parathyroid localization.

Adult↗
PubMed1994

A clinical-epidemiological study of hypertension in rural population of Jawan Block, Distt, Aligarh (UP) India.

A cross-sectional study was carried out in rural areas of Jawan Block District Aligarh, Uttar Pradesh, India covering a total population of 3760 drawn from 11 villages. The total number of confirmed hypertensives was 59 with a prevalence rate of 15.7 per 1000 of the general rural population. The prevalence of hypertension gradually increased with increase in age. Males were more prone to develop hypertension as compared to females. Obesity, social class and occupation had a direct impact on hypertension.

Adolescent↗
PubMed1994

Calcium pyrophosphate arthropathy of the spine: case report and review of the literature.

Calcium pyrophosphate deposition disease is a relatively uncommon arthropathy characterized by the clinical features of pseudogout, the radiographic manifestations of chondrocalcinosis, and the pathological deposition of calcium pyrophosphate crystals in both hyaline and fibrocartilage. Symptomatic involvement of the spine by calcium pyrophosphate deposition disease is rare except by nodular deposition in the ligamentum flavum and atlanto-occipital ligament. We report a 50-year-old woman who presented with an acute herniated disc syndrome secondary to an intraspinal inflammatory calcium pyrophosphate deposition disease mass at the level of the L4-L5 interspace. The magnetic resonance image and histopathological features of the case are also discussed.

Calcium Pyrophosphate↗
PubMed1994

Effect of experimental selenium deficiency and its supplementation on the candidacidal activity of neutrophils in albino rats.

The role of selenium in the diet of rats has been examined with respect to the neutrophil functions. Feeding of Se-deficient diet for 75 days resulted in reduction in candidacidal activity, superoxide production, oxygen consumption, glucose utilisation and glutathione peroxidase activity. Supplementing the diet with Se for 30 days resulted in partial restoration of all the activities.

Animals↗
PubMed1994

Computed tomography of normal and calcified coronary arteries.

The association between coronary artery calcification (CAC) and coronary artery disease is well established. The objectives of this article are to define the cross-sectional anatomy of the coronary arteries and to demonstrate the prevalence of CAC as seen on routine computed tomography (CT) of the thorax. A CT scan of a cadaver heart was performed in normal anatomic position. Additionally, a retrospective analysis of 103 consecutive thoracic scans was done by three experienced radiologists. The cross-sectional anatomy of the coronary arteries is described based on both these studies, and the prevalence of coronary calcification from the retrospective review was determined. The left anterior descending was the most commonly calcified artery (43% of all patients) followed in order by the left coronary (37%), circumflex (33%), and right coronary (20%). Seventy-nine percent of patients older than age 65 demonstrated coronary calcification on CT. This prevalence approaches that of reported autopsy series. Knowledge and understanding of the cross-sectional anatomy of coronary arteries is essential for detection of coronary artery calcification. We recommend that the presence of CAC should be reported on all thoracic CT scans because coronary calcification may signal unsuspected coronary artery disease.

Aged↗
PubMed1994

Clinical pharmacology of recombinant human follicle-stimulating hormone (FSH). I. Comparative pharmacokinetics with urinary human FSH.

OBJECTIVE: To assess and compare the pharmacokinetics of recombinant human FSH with those of a reference preparation of urinary human FSH. DESIGN: Urinary human FSH and recombinant human FSH (Metrodin and Gonal-F; Laboratoires Serono, Aubonne, Switzerland) were administered in a balanced, random order, crossover sequence as a single i.v. dose of 150 or 300 IU separated by 1 week of washout to 12 pituitary down-regulated, healthy female volunteers. Serum FSH concentrations were measured by an immunoradiometric assay (IRMA) and by an in vitro rat granulosa cell aromatase bioassay. Urine FSH concentrations were measured by IRMA. RESULTS: The mean concentration-time profiles after 150 IU of urinary human FSH and recombinant human FSH were superimposed, and the mean profile after 300 IU of recombinant human FSH was double that of the 150 IU dose. The data for both FSH preparations were well described by a biexponential equation. Total clearance of the preparations was comparable, judging from immunoassay and bioassay data (0.5 and 0.15 L/h, respectively). Based on the immunoassay, renal clearance of urinary human FSH was 0.1 L/h, whereas for recombinant human FSH it was slightly lower at 0.07 L/h, indicating that less than one fifth of the administered dose was excreted in the urine. Immunoassay showed that the two preparations were similar in terms of initial and terminal half-lives (2 and 17 hours, respectively). The volumes of distribution at steady state (11 L) were similar. The results of the in vitro bioassay confirmed this pharmacokinetic analysis. Just after i.v. administration, an initial decrease in the serum bioassay:immunoassay ratio was observed because of dilution of urinary human FSH or of recombinant human FSH in the residual endogenous FSH pool. Then the ratio increased progressively with time, suggesting either metabolic selection or activation of both types of injected human FSH toward forms with greater in vitro bioactivity. The bioassay:immunoassay ratio returned to baseline by day 7. CONCLUSION: The results obtained in this study indicate that the following [1] the pharmacokinetic characteristics of recombinant human FSH are similar to those of urinary human FSH; [2] the terminal half-life of human FSH is approximately 1 day; [3] after a single i.v. injection of human FSH a progressive increase in FSH bioassay: immunoassay ratio is observed; and [4] clinical use of recombinant human FSH could follow protocols and treatment regimens currently applied to urinary human FSH.

Adult↗
PubMed1994

Clinical pharmacology of recombinant human follicle-stimulating hormone. II. Single doses and steady state pharmacokinetics.

OBJECTIVE: To assess the single-dose pharmacokinetics of a recombinant human FSH preparation (Gonal-F; Laboratoires Serono, Aubonne, Switzerland), administered by i.v., IM, and SC routes and its pharmacokinetics at steady state after multiple dosing by the SC route. DESIGN: Twelve healthy down-regulated female volunteers received in random order three single doses of recombinant human FSH (150 IU, i.v., IM, and SC), with each administration separated by 1 week. The volunteers then received multiple recombinant human FSH doses by the SC route (150 IU one time per day) for 7 days. Follicle-stimulating hormone concentrations were measured by an immunoradiometric assay and an in vitro granulosa cell aromatase bioassay. RESULTS: After a single administration, the pharmacokinetics of recombinant human FSH were well-described by a two-compartment model after i.v. administration and by a one-compartment model with first order absorption after IM or SC administration. The mean total clearance of FSH was approximately 0.6 L/h, and renal clearance accounted for one tenth of the total elimination after i.v. administration. The distribution half-life was close to 2 hours. The terminal half-life was nearly 1 day when estimated either by modeling the i.v. data set or from analysis of the terminal phase of the steady state pharmacokinetic curve or from the time taken to reach steady state after repeated SC administrations. After single IM and SC injection, two thirds of the administered dose was available systemically. The cumulation factor for repeated SC administration was approximately 3 when steady state was reached. The in vitro bioassay data confirmed these estimations. The temporal evolution of the bioassay:immunoassay ratio suggests either metabolic selection or activation of recombinant human FSH toward forms with greater in vitro bioactivity. CONCLUSION: The estimation of the elimination half-life of approximately 1 day indicates that the maximal effect of a given dose of recombinant human FSH administered daily cannot be observed until 3 to 4 days of repeated administration. This indicates that, on a pure pharmacokinetic basis, physicians should wait at least 4 days to assess the efficacy of a given dose of recombinant human FSH and that they should not modify dosage too frequently.

Adult↗