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Biomedical subjects

R Khan

Publications and source records attributed to R Khan.

At least 109 records · Page 6Linked to original sources
PubMed1981

Alloreactive T cells: expression of HLA-D antigens, stimulation of autologous MLR, and possible immunoregulatory function.

Primed in MLC with allogeneic stimulators T cells acquire the capacity of expressing HLA-D and DR antigens and of stimulating the MLC response of autologous lymphocytes. When primed T cells from HTCs are used as stimulators, a bimodal distribution of responses with clear-cut "typing responses" and no significant "back stimulation" is observed. This pattern many be due to the expansion during priming of a population of HLD-D restricted suppressors since irradiated primed T cells inhibit the MLC responsiveness of HLA-A "compatible" lymphocytes. The development and size of such a population is not dependent, however, on the strength of the antigenic stimulus used for priming since no differences were seen between the pattern of reactions induced by T cells primed against HLA-D identical or HLA-D different cells. Primed OKT4+ and OKT8+ T cells share the capacity of expressing Ia antigens and of inducing "HLA-D restricted suppression." We suspected that a similar phenomenon accounted for the behavior of two HLA-D heterozygous cells as if they were HTCs. Although no suppression was found, the fact that these cells typed for their "silent" antigen when tested as responders, yet failed to express it when tested as stimulators, supports the theory that different genes control the MLC-responding and -stimulating capacities.

Antibodies, Monoclonal↗
PubMed1980

Myocardial infarction following acute aortic dissection.

Acute aortic dissection may present a clinical picture simulating myocardial infarction, including electrocardiographic changes. The mechanism underlying this mode of presentation has not heretofore been documented during life. We present here for the first time, a patient with acute aortic dissection and the clinical picture of acute myocardial infarction, where the mechanism of infarction has been demonstrated, by preoperative angiographic studies, probably to be due to compression of the extramural portion of the right coronary artery by the false channel of the dissecting hematoma.

Aortic Dissection↗
PubMed1980

Simultaneous anterograde fast-slow atrioventricular nodal pathway conduction after procainamide.

UNLABELLED: Three patients with paroxysmal supraventricular tachycardia underwent electrophysiologic studies that included His bundle recordings, incremental atrial and ventricular pacing and extrastimulation before and after intravenous infusion of 500 mg of procainamide. In all three patients the tachycardia was induced during atrial pacing or premature atrial stimulation, or both. Two of the three patients had discontinuous atrioventricular (A-V) nodal curves with induction of a slow-fast tachycardia during failure in anterograde fast pathway conduction and one patient had a smooth A-V nodal curve with induction of a slow-fast tachycardia at critical A-H interval delays. After procainamide: (1) in all three patients atrial pacing induced A-V nodal Wenckebach periodicity (cycle length 300 to 400 ms) resulting in simultaneous anterograde fast and slow pathway conduction (one atrial beat resulting in two QRS complexes) and retrograde fast pathway conduction initiating an echo response or a slow-fast tachycardia, or both; (2) in all three patients there was enhanced conduction and shortening of refractoriness of the anteriograde fast pathway and depressed conduction and lengthening of refractoriness of the retrograde fast pathway; and (3) in two patients there was inability to sustain tachycardia because of selective block within the retrograde fast pathway. IN CONCLUSION: (1) procainamide altered conduction and refractoriness of the anterograde fast and slow pathways so that simultaneous conduction could occur during atrial pacing, resulting in a double ventricular response and a slow-fast echo or tachycardia, or both; and (2) the differential effects of procainamide on anterograde fast and retrograde fast pathways suggests two functional A-V nodal fast pathways, oine for anterograde and the other for retrograde conduction.

Aged↗
PubMed1978

The uptake by the canine tibia of the bone-scanning agent 99mTc-MDP before and after an osteotomy.

The residue and extraction of technetium-labelled methylene diphosphonate (99mTc-MDP), a substance used in bone scanning, was examined in the canine tibia and found to be low. Examination of washout curves suggested that there were four compartments in cortical bone, a vascular, a perivascular, a bone fluid and a bone compartment. After an osteotomy in the canine tibia the residue of 99mTc-MDP increased. This was believed to be due to an increase in the blood supply to the bone and to an associated increase in new bone available for exchange. Bone scanning in a fracture is therefore a reflection of the vascular status of the bone being examined and of the uptake by bone. This is dependent on there being an adequate blood supply to the bone and an increased number of mineral-binding sites.

Animals↗
PubMed1977

Bone marrow acid phosphatase: another look.

Recent reports have indicated that bone marrow acid phosphatase is the most sensitive test in detecting bony metastases. The experience reported herein suggests that falsely positive results may be common, especially in patients with primary hematologic disorders. A plea is made that caution be given to the interpretation of this test so that some patients will not be denied appropriate therapy and the role of bone marrow acid phosphatase can be better defined by long-term followup in such patients.

Acid Phosphatase↗
PubMed1976

The effect of respiratory motion on the echocardiogram.

The effects of respiratory movements on the ultrasonic echoes of the cardiac structures were recorded and analyzed in 50 consecutive patients. Deep inspiration in cooperative patients resulted in a considerable increase of dense anterior echoes, with blotting out of any distal or posterior echoes in 12 of 44 patients (group A). In the second or larger series (32 of 44 patients; group B), a posterior displacement of most of the identifiable intrinsic cardiac echoes was seen with deep inspiration, particularly those of the posterior wall of the left ventricle. Forced expiration produced an opposite or anterior displacement of the cardiac echoes. Normal respirations showed similar but smaller excursions.

Echocardiography↗
PubMed1975

Grudge and the hysteric.

Our understanding of the bizarre sexuality of the hysteric began with Freud's discovery that its roots lay in infantile sexuality, but since then little knowledge has been added. This paper argues that the hysteric in early childhood deals with the failures of good-enough mothering and care by precocious sexual development, which is accompanied by an inability to be nurtured by any loving relationship. Sexual solutions to problems prove, for the hysteric, temporary, and inevitably end in grudge and complaints, as the love-object misreads the hysteric's gestures as expressing sexual wishes and desires instead of as a symbolic body language for care and protection. The author briefly examines the nature of the deprivation in childhood and the reason that the hysteric is such a promising yet recalcitrant patient, and offers a case illustration.

Fantasy↗