Biomedical subjects
Publications and source records attributed to K Miller.
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The response of serum insulin, growth hormone, plasma free fatty acids, triglycerides, and blood glucose to an oral glucose load was investigated in healthy White, African, and Indian subjects. Serum cholesterol, uric acid, platelet adhesiveness, and urine insulin clearance were also measured. Each racial group responded differently. Most striking were the differences between Africans and Whites; despite similar mean blood glucose values at all times during the test, the Africans had lower serum insulin levels, a lower urine insulin clearance, a much greater rise of growth hormone, a more definite and prolonged suppression of free fatty acid release, lower serum cholesterol and uric acid levels, and a trend towards lower plasma triglyceride values.The Indians tended to resemble Whites rather than Africans with respect to their insulin, growth hormone, cholesterol, and triglyceride levels. Their glucose tolerance was decreased compared with that of the other two groups, but suppression of their free fatty acids was enhanced. Platelet adhesiveness was similar in all three groups.The reasons for these differences are unknown, but must be related to genetic and environmental differences among the three races.
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BR6 mouse mammary tumours were maintained by serial s.c. transplantation into female or castrated male syngeneic hosts. The tumours could be broadly classified according to their structure, and usually remained stable through many passages. Occasionally, sarcomatous changes were seen (64 out of 800 cases). Pulmonary metastases were found in 5 per cent of mice bearing transplants of well-differentiated acinar tumours, in 34 per cent with tumours of the acinar/ductal type, and in 97 per cent with poorly differentiated tumours. There was a similar correlation between lymph node metastases and degree of primary tumour differentiation, the incidences being 0, 0.5 and 22 per cent respectively. Sarcomatous changes were associated with a reduced incidence of metastasis. Local invasion of muscle or peritoneum occurred in 32 per cent of mice with well-differentiated tumours, and in 59 per cent with less differentiated tumours. Selection for increased metastatic potential was not achieved by transplantation of lung nodules to a subcutaneous site.
This paper reports 121 laparoscopic cholecystectomies (LC) in patients who had had previous abdominal surgery between June 1990 and August 1992. There were 93 cases with lower abdominal scar (LS) and 28 with upper or umbilicus midline scar (US). For insertion of the laparoscope in the scarred abdomen we use the conventional laparoscopic approach (CLA), the peritoneum perforation under vision approach (PP), and the open laparoscopic approach (OLA). One hundred twenty scarred abdomens were completed successfully. Conversion to an open procedure was required in one case with previous LS, because of injury of the jejunum. One postoperative intraabdominal hematoma was noted and treated with percutaneous catheter drainage. No reoperation was required and no further complications were noted. Patients who had a previous laparotomy had no substantially longer operative time or postoperative hospital stay. Revealing a total complication rate of 1.6%, this study shows that previous abdominal surgery should no longer be considered a contraindication to LC.
We report on the case of a 24-year-old white man with a history of chronic leukemia treated with unrelated bone marrow transplantation and chemotherapy who was correctly diagnosed with appendicitis rather than typhlitis. The approach to diagnosing an acute abdomen in the leukemic patient is discussed, with particular focus on appendicitis vs. typhlitis. A focused CT scan proved to be instrumental in making the correct diagnosis of appendicitis in our patient. The literature on this topic for the past 30 years is reviewed. The purpose of our report is to demonstrate that despite the recent trend toward diagnosing RLQ pain as typhlitis which requires medical management, there are still instances where it 'really is' appendicitis. Appendicitis, therefore, must always be ruled out in the leukemic patient.
Since Fusarium-derived trichothecenes have shown immunosuppressive properties in laboratory animals, the possibility that deoxynivalenol (DON) and acetyldeoxynivalenol (AcDON) might affect the in vitro production of interleukins by macrophages or lymphocytes was studied. When the effects of low and high concentrations of DON on lymphocyte proliferation were compared, phytohaemagglutinin-induced proliferation was enhanced at concentrations between 0.005 and 0.5 ng DON/ml whereas 50 or 100 ng/ml caused a decrease in proliferation. In experiments in which lymphocytes were exposed briefly to 90 ng DON/ml, the level of thymidine incorporation was increased to 130% of control levels. Both DON and AcDON were shown to induce interleukin 1 (IL-1) release in peritoneal macrophages by a mode of action similar to that of cycloheximide. In the presence of DON, cellular IL-1 did not decay, and this resulted in a marked release of IL-1 from the cell during the period of exposure to the inhibitor. This suggests that in vivo effects of trichothecenes on the immune system may vary according to the level of exposure.
For many years the calcium ion has repeatedly cropped up in research work concerning the transformation of the normal cell to the malignant state. When these results are collected together they indicate that calcium may hold the key to the solution of many of the problems concerning the cancer cell.
Recent developments in computer-integrated and robot-aided surgery--in particular, the emergence of automatic surgical tools and robots--as well as advances in virtual reality techniques, call for closer examination of the mechanical properties of very soft tissues (such as brain, liver, kidney, etc.). The ultimate goal of our research into the biomechanics of these tissues is the development of corresponding, realistic mathematical models. This paper contains experimental results of in vitro, uniaxial, unconfined compression of swine brain tissue and discusses a single-phase, non-linear, viscoelastic tissue model. The experimental results obtained for three loading velocities, ranging over five orders of magnitude, are presented. The applied strain rates have been much lower than those applied in previous studies, focused on injury modelling. The stress-strain curves are concave upward for all compression rates containing no linear portion from which a meaningful elastic modulus might be determined. The tissue response stiffened as the loading speed increased, indicating a strong stress-strain rate dependence. The use of the single-phase model is recommended for applications in registration, surgical operation planning and training systems as well as a control system of an image-guided surgical robot. The material constants for the brain tissue are evaluated. Agreement between the proposed theoretical model and experiment is good for compression levels reaching 30% and for loading velocities varying over five orders of magnitude.
The introduction of cisplatin-based polychemotherapy has led to cure rates of up to 90% for the most frequent malignant diseases seen in young men. In view of these high cure rates, increasing clinical importance is now being attached to chemotherapy-induced fertility disorders. Comparative studies examining the impact of cytotoxic chemotherapy on gametogenesis demonstrate significant cytostatic- and dose-specific differences. The extensive literature on possible teratogenic effects of chemotherapy provides no evidence suggesting that offspring of patients with a history of chemotherapy have an increased risk of malformations. However, these studies, the scope and follow-up of which may still be inadequate, have failed to eliminate the fear of such risk. Hormonal protection from chemotherapy-induced testicular damage has thus far succeeded only in animal models pretreated by application of gonadotropin-releasing hormone agonists combined with nonsteroidal antiandrogens or testosterone plus 17 beta-estradiol. The same holds true for hormone therapy aimed at stimulating the recovery of spermatogenesis after chemotherapy-induced testicular damage. Cryopreservation of germ cells can be suggested to patients undergoing cytostatic therapy. In some cases, testicular extraction of spermatozoa can also be offered as a novel approach.
Causes of chromosomal nondisjunction is one of the remaining unanswered questions in human genetics. In order to increase our understanding of the mechanisms underlying nondisjunction we have performed a molecular study on trisomy 8 and trisomy 8 mosaicism. We report the results on analyses of 26 probands (and parents) using 19 microsatellite DNA markers mapping along the length of chromosome 8. The 26 cases represented 20 live births, four spontaneous abortions, and two prenatal diagnoses (CVS). The results of the nondisjunction studies show that 20 cases (13 maternal, 7 paternal) were probably due to mitotic (postzygotic) duplication as reduction to homozygosity of all informative markers was observed and as no third allele was ever detected. Only two cases from spontaneous abortions were due to maternal meiotic nondisjunction. In four cases we were not able to detect the extra chromosome due to a low level of mosaicism. These results are in contrast to the common autosomal trisomies (including mosaics), where the majority of cases are due to errors in maternal meiosis.