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Biomedical subjects

D C Heilbron

Publications and source records attributed to D C Heilbron.

35 records · Page 2Linked to original sources
PubMed1983

Choroidal melanoma growth patterns.

Thirty patients with choroidal melanoma in whom tumour thickness was found to increase on serial examination were retrospectively studied. Often when tumours started to increase in thickness, after a period of relative quiescence, the growth rate was relatively rapid. Increased tumour thickness was associated with increased tumour growth. During the phase of active tumour growth the height of the lesion tended to increase more than exponentially. Possible inadvertent biases in the selection of the patients studied prohibit wide-ranging conclusions from these data.

Choroid Neoplasms↗
PubMed1982

Chlamydia trachomatis and cervical neoplasia.

We tested 383 women with and 500 women without cervical neoplasia for antibodies against Chlamydia trachomatis or herpes simplex virus (HSV). Exposure to both agents was related to sexual activity, with the highest prevalence of antibodies found in women with more sex partners and who had first coitus at an earlier age. When subjects were matched for several risk factors (age, race, marital status, parity, number of sex partners, and history of venereal disease), a significant excess of antibodies against C trachomatis was found in cases as compared with control subjects (76.5% v 58.4%, respectively; n = 149). Because matched-pair analysis lost a substantial proportion of women with neoplasia (largely because they were older), linear logistic analysis was performed. This also showed an excess of antichlamydial antibody in cases, with an estimated odds ratio of approximately 2 for the association of antichlamydial antibody and the risk of being a case. Neither analysis found an excess of antibodies to HSV type 2 in cases.

Adolescent↗
PubMed1981

Factors influencing survival after therapeutic shunts. Results of a discriminant function and linear logistic regressions analysis.

Data on 100 consecutive patients undergoing portasystemic shunt at three hospitals of the University of California, San Francisco, were analyzed retrospectively to look for variables portending poor immediate and long-term outcome. As a determinant of early mortality after portacaval shunt, the Child's classification of the patient remains the single most important factor. If the patient is in Child's class C and has a hematocrit of less than 32 percent, he is even less likely to survive 30 days. The malnourished male patient who resumes drinking postoperatively is least likely to survive 1 year. Though short- and long-term mortality did not correlate with type of shunt, the prosthetic interposition mesocaval shunt was associated with an unacceptably high thrombosis rate of 20 percent in our institutions, and represented a technical failure to achieve the goal of preventing further variceal bleeding. No matter what type of shunt was performed, however, the 30 day mortality of Child's class C patients exceeded 50 percent. In the latter patients methods of treatment other than portasystemic shunts should be evaluated.

Adolescent↗
PubMed1981

The drainage of subretinal fluid: a randomized controlled clinical trial.

A randomized controlled clinical trial was conducted on a series of 120 consecutive cases of rhegmatogenous retinal detachment. One group of 60 eyes, randomly selected, was managed with a scleral buckling operation that included the drainage of subretinal fluid. The other group of 60 had a similar operation without drainage. A new method for evaluating complications, the "Complications Score," was devised. The score was higher (P = 0.005) for the drainage group, but this did not decrease the final anatomic or visual results. Eighty-seven percent of the drainage group was reattached with one operation, a figure not significantly different from the 83% reattached in the nondrainage group. The final cure rate after reoperations was 97% for both groups. The best corrected visual acuity, measured six months after operation, was not significantly different for the two groups. This study concludes that equally good results can be obtained with either a drainage or nondrainage operation.

Body Fluids↗
PubMed1981

Mycosis fungoides: diagnostic criteria based on quantitative electron microscopy.

Quantitative electron microscopy can provide objective measurements of nuclear atypia in lymphoid cells in skin biopsies during early stages of infiltration of the skin as part of inflammatory or neoplastic processes. This potentially provides a method for establishing reproducible criteria for determining whether an individual skin biopsy represents mycosis fungoides or is unlikely to represent mycosis fungoides. To investigate such criteria, quantitative electron microscopic studies of skin biopsies from 109 patients were performed. Seventy-seven patients had benign disorders, 16 patients had early mycosis fungoides, and 16 patients had controversial lesions. Measurements were made of lymphocyte nuclear profile perimeter and areas in electron micrographs. A nuclear contour index was calculated. On the basis of the mean degree of nuclear convolution alone, mycosis fungoides was not adequately distinguished from benign disorders. Better discrimination was achieved when the proportion of cells with a anuclear contour index of 9.0 or more was considered as an additional actor. When statistical methods were used to select discriminating factors, the best electron microscopic discrimination between benign and mycosis fungoides groups occurred when the proportion of cells with a nuclear contour index of 7 or more and the proportion of cells with a nuclear profile area greater than 30 sq. micrometer. were used together. Nomograms are presented which demonstrate the use of these criteria for a given case.

Aged↗
PubMed1980

In vivo oxygen dissociation curves in transfused and untransfused newborns with cardiopulmonary disease.

We used a new, rapidly responding in vivo catheter oximeter to continuously measure arterial oxygen saturation (Sao2) in 34 newborns with cardiopulmonary disease. The Sao2 was compared with the oxygen tension (Pao2) of blood sampled through the catheter in 2 groups. We evaluated the oxygen dissociation curves of 24 untransfused infants whose hemoglobin F (HbF) concentration was greater than or equal to 80%. We also examined the Sao2 curves of 20 extensively transfused infants who had greater than or equal to 80% hemoglobin A (HbA). We found a wide variation in Sao2 at levels of arterial Po2 between 30 and 90 mmHg. Although the oxygen dissociation curve of the transfused group was significantly to the right of the untransfused group, there was considerable overlapping between the 2 curves. This dispersion reflected the wide range of clinical states encountered in newborns with cardiopulmonary disease, and the changes in blood oxygen affinity. In some newborns, when Pao2 was less than 50 mmHg, Sao2 could be > 90% whereas in others, Sao2 could be < 75%. When both Pao2 and Sao2 were low, Sao2 reflected arterial oxygen contents more precisely because of the shape of the individual oxygen dissociation curves in both groups. Opinions vary as to the safe upper limit of Pao2 at which retrolental fibroplasia does not occur. The Sao2 at 2 upper limits of Pao2 (100 and 80 mmHg) was estimated by probit analysis of simultaneous measurements of Pao2 and in vivo Sao2. In both the untransfused and extensively transfused groups of newborns, Pao2 was < 100 mmHg when Sao2 was < 96%. The Pao2 was < 80 mmHg, when the Sao2 was < 92%, if the HbF was greater than equal to 80%, and when Sao2 was < 91%, if HbA was greater than equal to 80%, (95% confidence limits). The findings suggested a caveat against the practice of calculating Sao2 from measurements of pH, Pao2, and Paco2. This can be quite inaccurate when taking samples of arterial blood from newborns.

Blood Transfusion↗
PubMed1980

Prognostic significance of the pretreatment CT scan on time to progression for patients with malignant gliomas.

Case histories of 61 patients receiving multimodality therapy for primary malignant brain tumors were reviewed for factors visible on the computerized tomography (CT) scan that correlated with the interval of time from diagnosis and pretherapy evaluation to the time of documented tumor progression. The initial pretreatment CT scan of each patient was reviewed. Midline shift, peritumor low density (edema), the greatest diameter of tumor enhancement, and the greatest diameter of the intratumor low-density area were measured prior to radiation therapy and chemotherapy. Using a Weibull survival probability model, time to tumor progression was most satisfactorily fitted using two covariates, the volume of enhancing tumor (for instance, contrast-enhancing tumor less intratumor low density), and the presence of a peritumor low-density area. Patients who exhibited a small amount of contrast-enhancing tumor with peritumor low density tended to have a longer time to progression than patients with large contrast-enhancing tumor volume and no peritumor low density. Midline shift was not as important a variable as the extent of tumor contrast enhancement or peritumor low density.

Brain Neoplasms↗
PubMed1979

Relative biological effectiveness of low- and high-LET radiotherapy beams for jejunal crypt cell survival at low doses per fraction.

In order to determine the relative biological effectiveness (RBE) of various low- and high-LET radiotherapy beams of low coses, LAF1 mice were exposed to one dose and 10 equally fractionated doses of 60Co gamma rays, 137Cs gamma rays, 4-MeV x rays, 300-kVp x rays, helium ions in the plateau and Bragg-peak region, and 15-MeV neutrons; survival of jejunal crypt cells with the microcolony assay of Withers and Elkind was determined using 60Co as the standard. RBE values for the survival of 10 cells/circumference for 10 fractionated exposures (2.4 Gy [240 rad] per fraction of 60Co) were: 1.07 for 137Cs, 1.06 for 4-MeV x rays, 1.16 for 300-kVp x rays, 1.10 for helium ions in the plateau, 1.29 for helium ions in the peak, and 3.02 for 15-MeV neutrons. As LET increased, RBE increased with decrease of dose/fraction.

Animals↗
PubMed1977

A comparison of methods for quantitating fetal heart rate variability.

Fetal heart rate (FHR) variability is thought to be an important index of fetal health. In the presence of normal variability, the fetus is vigorous, but lack of beat-to-beat variability may be associated with fetal compromise. A distinction between short-term variability (STV) (beat-to-beat changes between successive beats) and long-term variability (LTV) (rhythmic fluctuations in FHR) has not been made to date. We have utilized computer programs to compare three pairs of mathematical indices and one visual index of FHR variability. Among the three pairs of indices designed for detection of STV and LTV, de Haan's short-term and long-term indices exhibited the least interdependence, and the long-term index was completely insensitive to artifically generated pure STV. Yeh's short-term and long-term indices exhibited substantial positive interdependence. Hon's visual index appears to detect LTV primarily rather than STV. When the effect of progression of labor on FHR variability was examined, no conclusions were possible because of inconsistencies between patients. Ultimately, the clinical value of any one of these indices awaits testing of their ability to define fetal well-being or fetal distress.

Analog-Digital Conversion↗