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Biomedical subjects

J Warren

Publications and source records attributed to J Warren.

At least 145 records · Page 8Linked to original sources
PubMed1982

Application of molecular genetics to the design of live herpes simplex virus vaccines.

In principle, several avenues for attenuation of herpes simplex viruses (HSV) are now available. These include intermixing of HSV-1 and HSV-2 genes by recombination, altering the regulation of gene expression and the deletion of viral genes not required for replication of the virus in permissive cells in culture. Results of analyses of HSV-1 x HSV-2 recombinants and of mutants containing a deletion in a gene expressed early in infection showed a loss of virulence when infected by intracerebral route into adult Balb/c mice. In addition, immunization of the mice by intracerebral route with relatively low doses of virus protected the mice from challenge with high doses (3000 LD50) of virulent virus. The application of genetic engineering to the construction of live vaccines is discussed.

Chromosome Deletion↗
PubMed1982

Gas chromatographic method for determining strychnine residues in alfalfa.

A gas-liquid chromatographic procedure is described for determining strychnine in alfalfa with a nitrogen-phosphorus detector. Alfalfa samples containing strychnine residues are chopped and extracted in a blender using ethyl acetate, sodium carbonate, and sodium sulfate, and the organic extract is extracted with 0.1N H2SO4 solution, made basic, and subsequently extracted with methylene chloride. Following concentration, the strychnine residues are quantitated by peak height, using an external standard. Recoveries for 0.05 ppm spikes were 88 +/- 11%.

Chromatography, Gas↗
PubMed1981

Selection of optimal features for classification of electrocardiograms.

The forward sequential selection and backward sequential rejection algorithms and the optimal branch and bound algorithm were evaluated in selection of features for classification of electrocardiograms of 237 patients with old myocardial infarction and 299 subjects without infarction. The branch and bound algorithm proved suitable for small sets of ECG features. However, the computational effort required was orders of magnitude greater than that for the other two methods and became prohibitive with large features sets. A satisfactory and consistent overall classification accuracy was achieved by using the sequential selection algorithms for selecting continuous features by maximizing the Mahalanobis distance at each step of the feature selection process. Maximization of the association index can produce better results but requires more computing effort. Feature selection based on maximizing sensitivity at each step for a fixed level of specificity is less satisfactory when a high level of specificity is required.

Computers↗
PubMed1981

Exploitation of the redundancy of the conventional limb lead electrocardiograms for prolongation of the record length.

A method is described for duplicating the usable record length for computer analysis of the conventional limb lead ECGs. The method is based on the use of the extensive redundancy contained in the limb leads when they are recorded by sequencing in groups of two or three leads at a time. The resultant increase in the number of ECG complexes available for computer analysis facilitates noise reduction procedures and improves the precision and repeatability of ECG measurements. A similar scheme is proposed for duplicating or triplicating the useful record length of lead VI or any other chest lead used for rhythm analysis. Finally, it is noted that the present formats of grouping of the conventional ECG leads are all suboptimal and a transition to simultaneous acquisition of all eight independent components of the 12-lead ECG is encouraged.

Computers↗
PubMed1981

Risks to the offspring of patients with some common congenital heart defects.

The families of 424 adult index patients with ventricular septal defect, right ventricular outflow tract obstruction, or combinations of these two abnormalities, were visited and interviewed, and whenever possible the children of index patients were examined clinically. Congenital heart defects were present in 9 of 308 children, 8 of 899 sibs, 4 of 840 parents, and 4 of 731 nephews and nieces of the index patients. The last three figures are likely to be underestimates owing to the design of the study. Comparison of pairs of affected relatives suggests that the group of lesions studied may have genetic determinants in common.

Adult↗
PubMed1981

Skin fibroblasts in Huntington disease.

We previously reported that skin fibroblasts with Huntington disease (HD) grew to higher maximal densities and, at early culture passages, attained more population doublings per week than did fibroblasts from control individuals. We also noted that HD cells were smaller and that larger colonies developed from single cells. In view of discrepant results reported from replications of the above studies, we undertook extensive blind studies with 10 coded pairs of HD and control cells in which all the skin biopsies were obtained by the same method, and the HD and control cells were grown identically at all times. No significant differences were found between HD and control cells in any of the above parameters in the current study. Some of the possible reasons for our failure to reproduce the previous results are discussed, chief among them may be the different treatment to which the HD and control cells might have been subjected prior to coming to our hands and the utilization of skin samples from different regions of the body.

Adult↗
PubMed1980

Optimal coding of electrocardiograms for epidemiological studies. The performance of human coders - astatistical model.

A statistical model is introduced to characterize the ECG coding process when multiple coding is performed by human readers. Triplicate reading and arbitration of disagreements would considerably reduce the miss rate with a concomitant increase in cost and effort. The results suggest that the use of the majority rule (acceptance of the most common code from multiple, blinded individual codings) is inappropriate for ECG coding. The model proposed gives a plausible explanation to the observed high miss rate in coding of rare events in spite of duplicate reading and arbitration of disagreements. The main problem identified is the high individual miss rate in a fraction of "difficult" ECG records suggested that efficient use of computer programs and visual verification may be required to reduce coding errors to an acceptable level.

Electrocardiography↗
PubMed1980

AKR murine leukemia viruses and long-term bone marrow cultures from AKR and SJL mice.

We have evaluated the effects of AKR mouse retroviruses on a system of long-term bone marrow cultures which allows prolonged replication of hemopoietic stem cells (CFUs) and granulocyte-monocyte progenitors with production of mature granulocytes. Ecotropic-nononcogenic virus is expressed in all cultures and does not adversely effect stem cell replication. We found, however, that cultures established from mice treated in vivo with lymphomagenic AKR viruses (Gross murine leukemia virus and AKR SL3 murine leukemia virus) showed a more rapid decline in CFUs and CFUc than cultures from "normal" AKR mice. Only the former cultures were found to produce lymphomagenic viruses. Furthermore, it was shown that addition of lymphomagenic virus to three-week marrow cultures established from AKR and SJL mice also caused a prompt decline in progenitor cell production and granulopoiesis when compared to medium-treated control cultures. The fate of all cultures was a loss of CFUc and granulocytes with a continuous production of macrophages. The change to macrophage production occurred earlier in the cultures treated with lymphomagenic virus or in those derived from lymphomagenic virus-treated animals. A study of these bone marrow-drived macrophage cultures, as well as cultures of similar morphology but of thymic origin, showed that they could be maintained as continuous lines. Cells from three of the cultures from lymphomagenic virus-treated animals plroduced locally growing sarcoma when inoculated into mice. The macrophages from the declined marrow cultures differed in certain properties from those of the established lines.

AKR murine leukemia virus↗
PubMed1980

The role of the Emergency Medical Services in organ donation.

A potential need for more organ donors has been identified because of the improved survival rates of patients receiving kidney transplants and the reports of improving graft success rates. Because of the development of the EMS trauma program, an awareness of the potential benefit for increased organ donation could be realized by improved working relationship of the EMS trauma unit and the organ recovery agency. In the final analysis, careful planning of a regionwide program for organ recovery by the organ retrieval groups to include the EMS trauma unit should result in an increased number of cadaveric kidneys for transplantation.

Cadaver↗
PubMed1980

Synergistic effect of combined hyperthermia and a nitrosourea in treatment of a murine ependymoblastoma.

The effectiveness of heat therapy in combination with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea on a murine ependymoblastoma was investigated. Based on survival time and the number of survivors, whole-body hyperthermia (40 degrees) increased the therapeutic effectiveness of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. Heat alone did not modify the course of the tumor. Microscopic evidence of accelerated tumor destruction in hyperthermic mice was apparent within 24 hr of drug administration. A temporary drop in animal weight was observed with hyperthermia at the higher dose levels of drug. Mechanisms which may be involved in this synergism are discussed.

Animals↗
PubMed1980

Echinostome cercarial penetration and metacercarial encystment as mortality factors for a second intermediate host, Biomphalaria glabrata.

Cercarial penetration and metacercarial encystment of Echinostoma liei in Biomphalaria glabrata caused high mortality of juvenile snails (3-8 mm in diameter) after 4 to 6 days of continuous exposure to about 150 cercariae per snail per day. Larger snails (10-13 mm) withstood cercarial penetration longer, significant mortality appearing 16 days after exposure. Life-table analysis showed that the snail mortality rate per age interval increased with increasing exposure to echinostome penetration. Single exposures of 3- and 6-mm snails to 500 cercariae caused 97% mortality for the former and 84% for the latter within 2 days. Snails surviving the first 2 days did not suffer further mortality when infected with as many as 488 metacercariae. Thus, mortality seems to result from penetration and early stages of encystment, rather than the presence of large numbers of metacercariae in the pericardial region. Growth of 3-mm snails exposed to 10 or 100 cercariae and of 6-mm snails to 500 cercariae was significantly less than the growth of unexposed controls after 20 days. Cercariae rapidly located the snails, 90% penetrating within 1 hr when individual, 6-mm snails were exposed to 100 cercariae in 5 ml of water. The high rate of cercarial penetration needed to cause snail mortality suggests that echinostome penetration and encystment will not cause much mortality of snail intermediate hosts in nature unless the density of echinostome cercariae is high.

Animals↗
PubMed1979

Therapeutic effect of prolonged hyperbaric oxygen in adjuvant arthritis of the rat.

Development of adjuvant disease in the rat is suppressed if hyperbaric oxygen is administered within one day after the inoculation of an oil suspension of Mycobacterium tuberculosis and continued for 16 to 17 days. Although 10 to 40% of the rodents developed mild arthritis after discontinuance of therapy, most remained symptom-free for at least 50 days. Oxygen administered after arthritis is advanced still exerted a significant curative effect. Possible mechanisms underlying the therapeutic action of oxygen are discussed.

Animals↗
PubMed1979

Death caused by brain herniation during hemodialysis.

Brain edema with brain herniation during or after dialysis has been reported previously. However, coexisting lesions of the central nervous system (CNS) which might play a facilitating role were present in these case reports. Described here is an 18-year-old white man with renal failure who developed clinical signs consistent with brain herniation while receiving his first hemodialysis treatment. He died two days later, after discontinuation of the supportive therapy and after the confirmation of brain death. Autopsy results documented brain edema with uncal and cerebellar tonsillar herniation without other coexisting pathologic lesions. The etiology of brain edema during the initial phase of dialysis is discussed.

Adolescent↗