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Biomedical subjects

M Kahn

Publications and source records attributed to M Kahn.

At least 91 records · Page 5Linked to original sources
PubMed1989

Synchronous intrauterine and ectopic pregnancy associated with clomiphene citrate.

Although synchronous intrauterine and ectopic pregnancies associated with the use of clomiphene citrate for infertility are rare, the actual incidence might, in fact, be considerably higher than previously thought. The cornerstone for ruling out an extrauterine gestation is the presence of sonographic evidence of an intrauterine pregnancy, as the possibility of concomitant intrauterine and extrauterine gestation is perceived to be statistically rare. This has resulted in an unacceptably high incidence of negative ultrasound interpretations. During a recent 12 month period, four women treated with clomiphene citrate for infertility were diagnosed as having concomitant intrauterine and ectopic pregnancies. Three had pelvic sonograms that were erroneous for the extrauterine component. However, successful evacuation of the products of ectopic gestation was performed in each, despite an immediate preoperative false-negative ultrasound report. Three of the women delivered healthy normal infants at full term, and the fourth woman spontaneously aborted the products of the concomitant intrauterine gestation. All four did well postoperatively, and no gross complications were encountered. Reassessment of ultrasound diagnostic criteria and the use of more sensitive methods, such as endovaginal ultrasound in high risk patients, are indicated for any symptomatic patient using clomiphene citrate for infertility. Awareness of the prevalence of this entity and the limitations of ultrasound will lead to prompt intervention and improved survival rates.

Clomiphene↗
PubMed1989

The nature and course of depression following myocardial infarction.

Two hundred eighty-three patients admitted to cardiac care units for myocardial infarction at two urban teaching hospitals were interviewed 8 to 10 days after infarction and 171 were reinterviewed 3 to 4 months later. Initially, 45% met diagnostic criteria for minor or major depression, including 18% with major depressive syndromes. Depression was not associated with the severity of cardiac illness but was associated with the presence of noncardiac medical illnesses. Three to 4 months after infarction, 33% of patients met criteria for minor or major depression. The large majority of patients who initially met criteria for major but not minor depression showed evidence of depression at 3 months and most patients with major depression had not returned to work by 3 months. Treatment of major depressive syndromes after myocardial infarction may reduce chronicity and disability, while minor depressive syndromes may be similar to normal grief and tend to be self-limited.

Aged↗
PubMed1988

The design and synthesis of mimetics of peptide beta-turns.

The synthesis of an 11 membered ring bis-lactam, a system which is designed as a conformationally restricted mimetic of type I and type II beta-turns is described. Computer assisted molecular modeling was used to compare the predicted low energy conformers of the turn mimetic with idealized type I and type II turn structures. Initial computational analysis indicates that the basic ring structure will provide an excellent foundation for the development of a varieity of beta-turn mimetics.

Designer Drugs↗
PubMed1988

A decade of experience with the glutaraldehyde-tanned human umbilical cord vein graft for revascularization of the lower limb.

Between October 1975 and November 1985, 907 lower limb bypasses were constructed in 715 patients (799 limbs) with glutaraldehyde-stabilized umbilical veins (UV-G) used as the predominant, or sole, graft material. Each reconstruction was classified in one of eight categories depending on the site of the distal anastomosis: above- and below-knee popliteal, anterior and posterior tibial, peroneal, trifurcation, sequential, and crural (tibial or peroneal) bypasses with adjunctive distal arteriovenous fistulas. Primary and secondary cumulative graft patency rates were determined for each category as well as cumulative actual palliation that combines end points of graft failure, amputation, and death. Half-life patencies for popliteal, tibial, and peroneal bypasses were 6.5, 2.3, and 1.7 years, respectively. Perioperative graft thrombosis occurred in 11% of popliteal reconstructions compared with 22% for the crural group. Nonocclusive graft failure caused by infection, aneurysm, or progressive foot gangrene occurred in 87 grafts (8%). The overall infection rate was 4.3%. Anastomotic aneurysms (1.4%) and strictures (2.1%) occurred infrequently as isolated phenomena. The incidence of graft dilatation and aneurysms assumed significant proportion after 5 years (36% aneurysms and 21% dilation); the diagnosis was particularly facilitated by B-mode imaging. Nevertheless, the overall clinical impact of graft degradation remained minimal (6% after 5 years). Twenty-two of 26 graft aneurysms were excised with successful graft replacement achieved in 10. During this 10-year period, our attitudes did change with regard to the indication for UV-Gs in relation to the maturation of infrapopliteal reconstructive surgery, appreciation of the superior results attainable with in situ saphenous vein, recognition of morphologic changes in long-term UV-G implants, and the growing documentation of poor results with polytetrafluorethylene in the crural position. We believe that UV-G is an acceptable alternative to the absent or deficient autologous vein, particularly in patients with limited life expectancy and where expediency may be a critical factor.

Adolescent↗
PubMed1987

Glucose and erythrocyte ATP: distinctive effects of dipyridamole and of ticlopidine.

This experiment suggests the following points: 1. Erythrocytes in control patients and in atherosclerosis patients seem to have a variable grade of affinity for adenosine and for plasma glucose. This variable grade seems to fix the level of the adenosine triphosphate (ATP) reserves and induces the erythrocytes' deformability. 2. The drop in the level of ATP reserves that induces the poor deformability of the erythrocytes in atherosclerosis patients would appear to be caused by two consecutive shortages: first a shortage that seems to be related to a deficiency of erythrocyte adenosine as the ATP shortage disappears with dipyridamole treatment and then a shortage induced by the lack of erythrocyte glucose and suppressed by the addition of ticlopidine to the dipyridamole treatment.

Adenosine↗
PubMed1986

The effects of transcriptional regulatory sequences introduced into a retroviral genome.

Chimeric plasmids in which the herpes thymidine kinase (tk) gene replaced portions of the Rous sarcoma viral genome were used to assess the relationship between viral transcription and that of an exogenous gene located within the viral genome. The entire tk gene and portions of the gene were positioned in both orientations within the viral gag and pol genomic region (which serves as intron for viral env mRNA). Microinjection assays then determined the amount of viral genomic transcription by quantitation of the amount of viral env mRNA produced. Separate injections also assayed for the presence of tk mRNA. Both mRNAs were produced unless the 3' region of the tk gene was present within the viral genome and in the same transcriptional sense. In this case viral env mRNA production was nearly abolished.

Animals↗
PubMed1986

Clinicopathologic studies of a case of aortic arch syndrome.

The clinicopathologic features of a 62-year-old woman with the aortic arch syndrome who presented with ischemic ocular inflammation, followed by complete loss of vision, is presented. The pathophysiology and ocular manifestations of chronic ocular ischemia are discussed.

Aortic Arch Syndromes↗
PubMed1986

Ocular features of carotid occlusive disease.

This article presents the clinicopathologic features of five patients with ocular involvement secondary to carotid artery disease. Three patients had the features of hypotensive retinopathy and two had panocular ischemia. In demonstrating the possible ocular and nonocular sequelae of carotid artery disease, this study stressed the importance of the recognition of the variable ocular features associated with carotid artery occlusive disease.

Aged↗
PubMed1986

Platelet hyperaggregability, blood prostacyclin and dipyridamole.

This study demonstrates the presence of PGI2 in blood and its influence on platelet retention tests, possibly by the intermediate of a releasing system in the columns, which is followed by a proximate recuperation on the erythrocyte sites after the passage. The presence of prostacyclin on the erythrocyte sites seems to depend upon the red cell deformability in relation to the good condition of their erythrocyte ATP reserve. The load of the erythrocyte sites increases with the daily dose of dipyridamole. The maximum load of the sites appears to be reached with a daily dose of dipyridamole 450 mg. Approximately 10% of the atherosclerosis patients who have been treated by dipyridamole keep their platelet hyperaggregability and their abnormally lowered prostacyclin level.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Primary and adjunctive intra-arterial digital subtraction arteriography of the lower extremities.

Standard contrast arteriography (SCA) and intra-arterial digital subtraction arteriography (DSA) were performed during a 26-month period in 459 cases. The DSA group consisted of 22 aortoiliac studies, 66 crural-pedal arch studies, and 227 combinations. In addition, postoperative DSA was performed in 42 patients to evaluate graft patency, morphology, and inflow and runoff circulations. There were no significant differences in the quality of the preoperative aortoiliac studies performed by either SCA or DSA although, in select cases, one or the other of these techniques resulted in a superior study. Distal crural-pedal arch visualization was enhanced with DSA compared with SCA (85% vs. 65%) but when both were compared with their corresponding intraoperative completion arteriograms, the interpretive error rates resulted in comparable accuracies, false positive and negative rates, and predictive values. The likelihood of achieving graft patency in patients who have unsatisfactory preoperative visualization of the distal circulation by DSA is reasonable (11 of 27 patients) but inferior to the number obtained when there is adequate DSA visualization (40 of 53 patients). We conclude that DSA is a valuable adjunct to preoperative SCA but should not be used as the sole criterion for the assessment of operability for limb salvage. Intraoperative prereconstruction arteriography or direct surgical exploration of the crural arteries in patients with inadequate preoperative visualization will result in graft patency in a significant percentage of cases. Intra-arterial DSA for postoperative evaluation of lower limb bypass adds another dimension to analysis of graft structure and status of the host circulatory beds and also provides a method for accurate interpretation of postoperative data.

Angiography↗
PubMed1985

Bacteriophage P4 DNA replication. Location of the P4 origin.

An electron microscopic examination of replicating bacteriophage P4 DNA molecules has revealed theta-type structures that replicate bidirectionally from a single origin. Many replicating P4 DNA molecules also contain long (2000 bases) single-strand DNA regions at the growing fork that are deployed in a trans configuration, which supports the concept of continuous leading strand and discontinuous lagging strand syntheses. The position of the P4 origin was localized by the use of a plasmid complementation test for replication in vivo, as well as by labeling of DNA replicating in vitro in the presence of a chain-terminating inhibitor. During this study we discovered a second site on the P4 genome which is essential for replication, and we have named it crr (cis region required for replication). The site is located at least 3300 bases from the origin but appears to be required for the initiation of DNA replication in vivo as well as in vitro.

Coliphages↗
PubMed1985

Omental protection of autogenous arterial reconstruction following femoral prosthetic graft infection.

Vascular graft infections in the femoral region that require synchronous revascularization are generally reconstructed with prosthetic grafts via extra-anatomic routes. If in situ revascularization is required, then autologous tissue provides optimal results. A particular challenge in this circumstance is achieving soft tissue coverage of the reconstruction where wide and radical débridement has removed the tissues ordinarily used for this purpose. If muscle flaps are not available or possible, the use of omentum is advocated. The omentum can be easily reached from behind the inguinal ligament and transposed on its bipedicled vascular base for coverage of vital structures in the femoral triangle, thereby obliterating dead space and providing a surface for both temporary and permanent skin coverage. The procedure is quite simple, can be performed rapidly, and should be considered for use in the dire situation that requires soft tissue coverage of exposed vessels in extraperitoneal locations.

Blood Vessel Prosthesis↗
PubMed1985

Adventitial cystic disease of the popliteal artery: failure of percutaneous transluminal angioplasty as a therapeutic modality.

Adventitial cystic disease of the popliteal artery is an important cause of peripheral vascular insufficiency in the young and middle-aged man. The pathologic feature is a mucinous cyst located within the adventitia of the artery that expands and secondarily compromises the vessel lumen. Although physiologically quite different, this process is easily mistaken for arteriosclerosis. The clinical history of sudden claudication in a young nonsmoking man, combined with characteristic angiographic features, are important clues to the correct underlying pathology. Treatment generally consists of cyst evacuation or local bypass. This article was prompted by the failure of percutaneous transluminal angioplasty to achieve durable success in controlling this unique type of arterial disease. Subsequent surgical intervention proved satisfactory, lending support to this modality as the treatment of choice.

Angioplasty, Balloon↗
PubMed1985

Clinical evaluation of cefotiam and cefamandole in respiratory tract infections.

Eighty-two adult hospitalized patients suffering from respiratory tract infections were treated with cefotiam or cefamandole in an open comparative study. The patients were allocated randomly to one of the two treatments. The recommended dosage regimens (i.m. or i.v.) were used for both groups (cefotiam 1 g b.i.d., cefamandole 1 g t.i.d.). The duration of treatment was 7 to 14 days according to the response of the disease condition. 80 patients were analyzed. The tolerability of both drugs was good and comparable. The clinical and bacteriological efficacy of both drugs was equivalent. The radiological examinations showed a better improvement of the patients treated with cefotiam.

Adolescent↗
PubMed1984

Improved patient selection for enzymatic lysis of peripheral arterial and graft occlusions.

Intraarterial thrombolysis by remote intravenous or direct intraarterial infusion of streptokinase is possible. The latter may be more effective with a lesser potential for systemic hemorrhagic complications because of the smaller dose administered directly in the area. Fifty patients with prosthetic graft, embolic, and renal artery occlusions were evaluated. Embolic occlusion responded dramatically, particularly since lytic therapy was initiated at an early stage. Patients with severe ischemia or those with simple localized occlusion were best treated by surgical means. Successful thrombolysis was also obtained with renal artery occlusions combined with percutaneous transluminal angioplasty. The management of patients with prosthetic graft occlusion by lytic therapy is complex. Optimal results can be obtained in patients presenting with occluded grafts after the immediate postoperative period and in those in whom previous satisfactory runoff has been demonstrated. Failure of lysis in this group is associated with a high incidence of limb loss due to unreconstructable obliterative disease. Successful lysis of occluded prosthetic grafts will often require corrective angioplasty or surgical revision.

Adult↗