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Biomedical subjects

J W Allen

Publications and source records attributed to J W Allen.

At least 181 records · Page 10Linked to original sources
PubMed1978

Musical murmurs: an echo-phonocardiographic study.

Five patients with muscial murmurs were studied noninvasively with simultaneous echocardiography and phonocardiograpy and phonocardiography. Three patients had aortic regurgitation, one mitral regurgitation and one tricuspid regurgitation. The frequency of the muscial murmurs ranged from 40 to 158 cycles/sec. The patient with tricuspid regurgitation manifested an inspiratory honk. Simultaneous echo-phonocardiography revealed regular valve leaflet flutter (aortic, mitral or tricuspid) at a frequency identical to that of the simultaneously recorded muscial murmur. This study demonstrates that echocardiography is a useful noninvasive tool in identifying the site of origin of musical murmurs.

Adult↗
PubMed1978

Bromodeoxyuridine tablet methodology for in vivo studies of DNA synthesis.

5-Bromodeoxyuridine (BrdU) tablets with different physical characteristics are useful in a wide variety of studies requiring detection of DNA replication in vivo. These tablets can effect a high substitution of BrdU in DNA, thereby permitting sister chromatid differentiation in chromosomes stained with 33258 Hoechst alone or in conjunction with Giemsa. Baseline and cyclophosphamide-induced in vivo sister chromatid exchange frequencies in mouse spleen, marrow, and thymus were measured and found to be significantly greater than those in spermatogonia. Sister chromatid exchange analysis was also extended to mouse liver and to Chinese hamster and Armenian hamster marrow cells. Sister chromatid differentiation was observed in Armenian hamster meiotic tissue, and evidence for interhomolog chromatid exchange obtained.

Animals↗
PubMed1978

Problems in ultrasonic estimates of septal thickness.

Problems related to cardiac anatomy and ultrasonic instrumentation affect the accuracy of echographic identification of endocardial echoes. A cadaver model and 13 patients were studied, with direct identification or with the aid of echographic contrast techniques, to identify accurately the endocardial echo. The study showed that (1) echographic contrast agents delineate an endocardial echo in the central portion of the ultransonic beam; (2) a specular reflector exists within the right ventricular cavity; (3) specular reflectors within the septum may give the false appearance of border-forming echoes; (4) septal thickness varies by 1 to 5 mm after the endocardial echo has been identified by the contrast agent; and (5) spurious echoes, related to a wide beam angle, can be confused with the endocardial echo. In light of these problems, three criteria were utilized for endocardial echo identification: the prominent notch in the left septal echo, the specular quality of the right septal echo, and the association of multiple myocardial echoes moving in parallel. With these criteria, the endocardial echoes in 11 of the 13 patients could be accurately identified without the use of a contrast agent. The identification of these problems should provide helpful guidelines in developing more accurate and reproducible criteria for septal thickness measurements.

Cadaver↗
PubMed1977

The role of serial echocardiography in the evaluation and differential diagnosis of pericardial disease.

Echocardiography is an established method for the diagnosis of pericardial effusion. Echographic findings in fibroadhesive disease have also been described. The interpretation of a changing serial echogram during the clinical course of pericardial disease has not been established. Sixteen patients with echographic evidence of pericardial effusion were followed with serial echographic studies. In seven, surgical or autopsy correlation was obtained. Because of the serial changes noted we undertook a study in dogs to clarify the problem of variability in intensity of sound reflected from the pericardial space. Three open-chested dogs were studied with rapid sequence surface echograms as blood introduced into the pericardial space was converted from the unclotted to the clotted state. In all three dogs blood clooting increased the intensity or sound reflected from the pericardial space. Our study of two patients with fibroadhesive pericardial disease documents serial changes in echoes from the pericardium and pericardial space accompanying the clinical evolution of the disease process, and suggests a method for avoiding the commonly encountered difficulty in proper identification of the pericardial and epicardial echoes. Our preliminary studies suggest that serial echograms should play an important role in the management of patients with pericardial effusion; further surgical/pathological correlations are required.

Adult↗
PubMed1977

A simplified technique for in vivo analysis of sister-chromatid exchanges using 5-bromodeoxyuridine tablets.

A small tablet of 5-bromodeoxyuridine (BrdU), implanted subcutaneously in a mouse, provides sustained release of base analog sufficient to effect substitution of DNA throughout an entire replication period. As illustrated by studies of mouse bone-marrow and spleen cells in the presence or absence of cyclophosphamide, this depot method of BrdU administration greatly simplifies in vivo analysis of sister-chromatid-exchange formation.

Animals↗
PubMed1976

In vivo BrdU-33258 Hoechst analysis of DNA replication kinetics and sister chromatid exchange formation in mouse somatic and meiotic cells.

BrdU (5-bromodeoxyuridine)-33258 Hoechst methods have been adapted for in vivo analyses of replication kinetics, sister chromatid differentiation and sister chromatid exchange (SCE) formation in mice. Sufficient in vivo BrdU substitution for cytological detection was effected with multiple intraperitoneal injections of the analogue. The combination of centromere staining asymmetry and sister chromatid differentiation at metaphase permits unambiguous determination of the number of replications in BrdU and dT (deoxythymidine) undergone by individual cells. Late-replicating regions in marrow and spermatogonial chromosomes are highlighted by bright fluorescence after sequential incorporation of BrdU followed by dT during a single DNA synthesis period. SCEs are analyzed in marrow and spermatogonial metaphases after successive complete cycles of BrdU and dT incorporation. Significant induction of SCE was observed with both mitomycin C and cyclophosphamide; the latter drug requires host-mediated activation to be effective. In meiotic metaphase cells harvested two weeks after BrdU incorporation, satellite DNA asymmetry, sister chromatid differentiation and SCE could be detected in a few chromosomes, most frequently the X and the Y.

Animals↗
PubMed1975

Evaluation of cardiovascular and pulmonary changes during meperidine-diazepam anesthesia.

Studies were conducted in 189 oral surgery out-patients to evaluate the combination of meperidine hydrochloride and diazepam for anesthesia and to determine its effect on the cardiovascular and pulmonary systems. Results showed that neither ventricular cardiac arrhythmias nor clinically significant respiratory depression occurred in the sedated patients; meperidine-diazepam proved to be satisfactory for oral surgical procedures.

Adolescent↗