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Biomedical subjects

J Miller

Publications and source records attributed to J Miller.

At least 973 records · Page 54Linked to original sources
PubMed1982

The viscosity of acrylic bone cements.

The viscosity of the acrylic bone cement used in total joint arthroplasty is an important material property for determination of the proper handling characteristics and interlock with bone. In this article the rheological properties of the three leading bone cements were determined over a three-decade range of shear rates. In addition, four other cements were tested at a single shear rate. The results indicate that all the acrylic bone cements are non-Newtonian, pseudoplastic materials with significant differences between them. It is shown that the viscosity increases at different rates with respect to increases in time. For the majority of cements there is a steady or increasing rate of viscosity change with time.

Biomechanical Phenomena↗
PubMed1982

Binding of crocetin to plasma albumin.

The binding of the carotenoid crocetin to human and bovine plasma albumin was studied using absorption and fluorescence techniques. Shifts in the absorption spectrum of crocetin, quenching of the albumin fluorescence, and competitive binding studies all provided information about the binding of crocetin to albumin. These studies suggest that crocetin binds to plasma albumin by occupying the free fatty acid binding sites. The binding constants for the first two binding sites are in the 10(5)-10(7) M-1 range and are an order of magnitude less than the values reported for other conjugated polyene fatty acids. The importance of this strong plasma albumin binding to the pharmacology of crocetin is discussed.

Animals↗
PubMed1982

A method for large-scale, high-yield isolation of canine pancreatic islets of Langerhans.

A modified collagenase digestion method is described for the isolation of large numbers of islets from the canine pancreas (approximately 3,500 islets/g). The islets isolated by this technique remained viable and released insulin in response to secretagogues after one week of maintenance in tissue culture. Islets isolated from a single donor pancreas were re-implanted into the spleen of the same animal made diabetic by subtotal pancreatectomy and two injections fo streptozotocin. Hyperglycemia was corrected in two dogs and decreased in a third dog followed for 30 days. The islet isolation method is described, therefore, provides a sufficiently large yield of viable islets from one donor pancreas to correct or improve diabetes in a recipient animal.

1-Methyl-3-isobutylxanthine↗
PubMed1982

High-frequency jet ventilation in oral and maxillofacial surgery.

The oral and maxillofacial surgeon faces many situations in which maintenance of the patient's airway can be a problem. Facial trauma, severe infection, and trismus all can compromise the airway and pose a dangerous situation. The use of high-frequency jet ventilation (HFJV) via transtracheal puncture offers excellent airway protection with minimal patients discomfort prior to induction of anesthesia. The use of a large, cuffed endotracheal tube for blind awake nasal intubation, or in conjunction with tracheostomy, can be eliminated in many situations. HFJV offers minimal trauma to nasal passages and larynx while preventing aspiration. During emergence, discomfort is reduced to a minimum, and the patient can communicate verbally. These same advantages apply to patients who receive outpatient oral surgery. Therefore, in the choice of an anesthetic technique, HFJV should be a definite consideration.

Adult↗
PubMed1982

Stool viruses in babies in Glasgow. 4. Further hospital studies.

The events occurring during the time in hospital of 24 babies were recorded in detail, particularly those related to bowel function. The babies were admitted to a general paediatric unit with various diagnoses a total of 27 times during a six month period. The purpose of the study was to fill gaps in the records of a previous study (Scott et al. 1979) and to try to relate excretion of viruses detectable by electron microscopy to disturbances of bowel function (diarrhoea and/or vomiting). The results showed that a variety of viruses were associated with gastroenteropathy, that virus excretion could occur without disease and that hospital acquisition of virus is not uncommon. Antiobiotic treatment did not appear to precipitate diarrhoea in this small number of babies.

Anti-Bacterial Agents↗
PubMed1982

Discrete versus continuous stage models of human information processing: in search of partial output.

This article introduces a new technique designed to study the flow of information through processing stages in choice reaction time tasks. The technique was designed to determine whether response preparation can begin before stimulus identification is complete ("continuous" models), or if a stimulus must be fully identified prior to any response activation ("discrete" models). To control the information available at various times during stimulus identification, some relevant stimulus characteristics were made easy to discriminate and some were made hard to discriminate. The experimental strategy was to look for effects of partial output based on information conveyed by characteristics that were easy to discriminate. The technique capitalized on the fact, demonstrated in Experiment 1, that preparation of two response fingers on the same hand is more effective than preparation of two response fingers on different hands. The usefulness of partial output was varied by manipulating the assignments of stimuli to responses. For some mappings partial information could contribute to effective response preparation because the responses consistent with partial information were assigned to fingers on the same hand. For other mappings partial information could not contribute to effective response preparation because the responses consistent with partial information were assigned to fingers of different hands. Performance differences between these mappings were considered evidence that partial information about a stimulus was transmitted to response activation processes before the stimulus was uniquely identified, and thus were considered evidence against discrete transmission of information about the stimulus as a whole. A variety of stimulus sets were studied; the results suggest that information is transmitted discretely with respect to stimulus codes, although distinct codes activated by a single stimulus may be transmitted at different times.

Adult↗
PubMed1982

Evolution of mouse immunoglobulin lambda genes.

The mouse has four C lambda and two V lambda genes. We have isolated Charon 4A clones that contain all six lambda genes from a BALB/c germ-line library. We present here the DNA sequences of the C lambda 2, C lambda 3, and C lambda 4 genes and also correct what are apparently errors in previous reports of C lambda 1 protein and DNA sequences. In addition, we have analyzed cloned DNAs by restriction mapping and electron microscopy to determine the relationships among the various lambda genes. By heteroduplex analysis, two gene clusters containing JC lambda 3--JC lambda 1 and JC lambda 2--JC lambda 4 show homology extending from the J regions 5' of C lambda 3/C lambda 2 to just 3' of C lambda 1/C lambda 4. Other than the region between the genes, very little homology exists in the C lambda flanking regions. In contrast, V lambda 1 and V lambda 2 genes show considerable homology extending into the 5' flanking regions. Large inverted repeats are found in the 5' flanking regions of V lambda 1 and C lambda 3, as well as in the 3' flanking regions of both C lambda gene clusters. DNA sequence divergences between the C lambda genes indicate that an ancestral JC lambda x--JC lambda g gene cluster arose at about the time of the first mammals by duplication of a primordial JC lambda gene. The data further suggest that the JC lambda x--JC lambda gene cluster duplicated after the speciation of mouse and man and subsequently diverged into the present day JC lambda 3--JC lambda 1 and JC lambda 2--JC lambda 4 gene clusters. C lambda 4, a pseudogene, became inactive at about the time of duplication of the ancestral JC lambda x--JC lambda y cluster. Comparison of DNA sequence divergence between the V lambda 1 and V lambda 2 genes demonstrates an anomaly. The percentage of amino acid replacement changes is approximately the same for V lambda 1/V lambda 2 as for C lambda 3/C lambda 2, implying that the ancestral V lambda gene was duplicated at the same time, and possibly together with, the JC lambda x--JC lambda y cluster. However, there are fewer silent changes than amino acid replacement changes between the V lambda 1/V lambda 2 genes, suggesting either that a selective pressure acted on the silent sites or that V lambda genes have only recently been duplicated. We also consider the possibility of a gene conversion event subsequent ot a more ancient duplication.

Animals↗
PubMed1982

Metastatic calcification of the choroid in a patient with primary hyperparathyroidism.

This case report documents for the first time the funduscopic appearance and the fluorescein angiographic and ultrasonographic findings of what probably represents sclerouveal metastatic calcification in a patient with a past history of hyperparathyroidism. Fluorescein angiography revealed window defects centrally and mild staining of the more prominent periphery of the lesions. B-scan ultrasonography revealed marked sonoreflectivity characteristic of calcium.

Aged↗
PubMed1982

Studies on the survival of simultaneous canine renal and segmental pancreatic allografts.

Prolonged survival of the vascularized free-draining intraperitoneal pancreatic segmental allografts (FDPS) has been observed previously in immunosuppressed beagle littermates matched for low mixed lymphocyte culture (MLC) reactivity. When rejection (hyperglycemia) did occur, it was abrupt, unpredictable, and irreversible. This contrasts with renal allograft rejection in which elevations of serum creatinine are reversible with increased immunosuppression. In the present experiments, low MLC-reactive littermate pairs underwent simultaneous transplantation of kidney and FDPS allografts from the same donor. Increases in serum creatinine from 0.5 mg/dl to 1.5 mg/dl (renal rejection) occurred 4 to 5 days after transplantation (mean = 20.5 +/- 4.1) and preceded the onset of hyperglycemia by 6 to 22 days (mean = 1.06 +/- 4.6) in nonimmunosuppressed animals. At the onset of kidney rejection but before hyperglycemia developed, renal allograft biopsies revealed generalized mononuclear infiltration, while FDPS biopsies showed diffuse interstitial infiltration, but islets of Langerhans appeared to be spared. Treatment intervention with azathioprine and corticosteroids at the time of creatinine elevation prevented the onset of hyperglycemia from 46 to greater than 260 days in four of nine animals. Biopsies after 2 weeks of therapy showed resolution of the lymphoid infiltrates in the kidney and limitation of infiltrates to perivascular areas in the FDPS allografts. Immunological monitoring of peripheral blood lymphocyte function demonstrated the development of positive in vitro cell-mediated lymphocytoxicity shortly before the onset of hyperglycemia but only after creatinine elevation was well established and biopsies revealed evidence of rejection in both the renal and FDPS allografts.

Animals↗
PubMed1982

Transient and residual stresses and displacements in self-curing bone cement - Part I: characterization of relevant volumetric behavior of bone cement.

In this first part of a two-part report, some aspects of the volumetric behavior of bone cement during its curing process are examined as a prelude to an analysis for the transient and residual stresses and displacements in stem fixation systems. Experiments show that stress generation in the cement is associated with its temperature while curing and that during the cooling phase, the stresses are mainly due to thermal as opposed to bulk shrinkage. The appropriate coefficient of thermal expansion of bone cement has been evaluated from measurements in a simulated fixation system in conjuction with a thermoelastic analysis.

Acrylates↗
PubMed1982

Transient and residual stresses and displacements in self-curing bone cement - Part II: thermoelastic analysis of the stem fixation system.

In this second part of a two-part report, an idealized model of the stem fixation system is analyzed to determine the adverse effects of the thermal stresses and displacements of bone cement during its curing process. The Shaffer-Levitsky stress-rate strain-rate law for chemically hardening material has been used. The results show that if the cement is surrounded by cancellous bone, as opposed to cortical bone, then transient tensile circumferential stresses in the cement and similar radial stresses at the stem/cement interface are generated. The former may cause flaws and voids within the still cement, while the latter may cause gaps at the interface.

Bone Cements↗
PubMed1982

Cross validation of serum to saliva relationships of caffeine, theophylline and total methylxanthines in neonates.

We have previously described the relationships of serum and saliva concentrations of caffeine, theophylline and total methylxanthines in premature infants. We have now extended the previous studies in order to validate the previously derived relationships with new data. The new serum to saliva relationships, derived using regression and ratio models, are cross validated against the relationships from the previous data, and vice versa. A good cross validation was observed for caffeine and total methylxanthine concentrations in infants treated with caffeine. In the theophylline treatment group, theophylline concentrations did not cross validate well, whereas the total methylxanthine concentrations did. Since in vivo conversion of theophylline to caffeine and vice versa may affect the individual methylxanthine relationships, the total methylxanthine equations are recommended for predicting serum concentrations from salivary concentrations.

Apnea↗