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Biomedical subjects

J Newell

Publications and source records attributed to J Newell.

At least 73 records · Page 4Linked to original sources
PubMed1984

Portal systemic encephalopathy.

Portal systemic encephalopathy is a neuropsychiatric disorder that occurs secondary to chronic liver disease. It is a chronic and disabling disorder that must be treated concurrently with liver disease. In chronic liver disease, the regenerative capacity of the liver to produce new cells is eventually hampered and scar tissue develops. Scarring reduces blood flow through the liver. The vein most affected is the portal vein which contributes 75 percent of the blood to the liver as it evolves from tributaries off the abdominal organs. To eliminate the high pressure in the portal vein caused by the reduced blood flow, the portal vein develops collateral vessels that bypass the liver and drain directly into the inferior vena cava. When blood is not cleared, or when hepatic functioning fails, toxins accumulate in the circulation and affect the central nervous system. The neuropsychiatric manifestations that occur represent the symptoms seen in portal systemic encephalopathy. With renewed understanding of the disease and its neuropsychiatric manifestations, both clinicians and patients are able to minimize its untoward effects. This article reviews the pathogenesis, stages, diagnosis and treatment of the disease and aims at giving nurse practitioners a thorough review so they can better teach patients how to help themselves.

Anti-Bacterial Agents↗
PubMed1983

Molecular anatomy of the antibody binding site.

The binding region of immunoglobulins, which includes the portion of the molecule having the most variability in its amino acid sequence, is shown to have a surprisingly constant structure that can be characterized in terms of a simple, well-defined model. The binding region is composed of the antigen combining site plus its immediate vicinity and arises by noncovalent association of the light and heavy chain variable domains (VL and VH, respectively). The antigen combining site itself consists of six polypeptide chain segments ("hypervariable loops") which comprise some 80 amino acid residues and are attached to a framework of VL and VH beta-sheet bilayers. Having analyzed refined x-ray crystallographic coordinates for three antigen-binding fragments (Fab KOL (Marquart, M., Deisenhofer, J., and Huber, R. (1980) J. Mol. Biol. 141, 369-391), MCPC 603 (Segal, D., Padlan, E. A., Cohen, G. H., Rudikoff, S., Potter, M., and Davies, D. R. (1974) Proc. Natl. Acad. Sci. U. S. A. 71, 4298-4302), and NEW (Saul, F. A., Amzel, L. M., and Poljak, R. J. (1978) J. Biol. Chem. 253, 585-597] we use the results to introduce a general model for the VL-VH interface forming the binding region. The region consists of two closely packed beta-sheets, and its geometry corresponds to a 9-stranded, cylindrical barrel of average radius 0.84 nm with an average angle of -53 degrees between its two constituent beta-sheets. The barrel forms the bottom and sides of the antigen combining site. The model demonstrates that the structural variability of the binding region is considerably less than was thought previously. Amino acid residues which are part of the domain-domain interface and appear not to be accessible to solvent or antigen contribute to antibody specificity.

Amino Acid Sequence↗
PubMed1981

Correlation of patterns of subendocardial reperfusion and left ventricular performance after ischemia.

Ninety-three dogs were studied with normothermic or hypothermic ischemia for 60 or 90 minutes, with or without potassium cardioplegia. Radioactive-labeled microspheres (9 +/- 1) were injected into the aortic perfusion cannula just prior to aortic cross-clamping and at 2, 6, and 10 minutes after the clamp was released. Left ventricular (LV) function was analyzed with a right heart bypass model before and 45 minutes after the ischemia period. Changes in LV function were defined as the arithmetic difference in the center of mass between preischemia and postischemia computer-drawn Sarnoff curves. Regardless of technique of myocardial protection, increased subendocardial flow 2 minutes after ischemia correlated strongly with preservation of LV function (p less than 0.01). Well-preserved hearts showed a rapid return to normal levels of coronary blood flow (p less than 0.01). In contrast, a delay in the peaking of subendocardial flow to 10 minutes was associated with poor function (p less than 0.01). There was a high correlation between ultrastructural morphology and LV function. While well-preserved hearts showed early preferential subendocardial perfusion, the poorly protected myocardium is unable to restore adequate subendocardial flow early in the reperfusion period.

Animals↗
PubMed1978

Unexplained in-hospital fever following cardiac surgery. Natural history, relationship to postpericardiotomy syndrome, and a prospective study of therapy with indomethacin versus placebo.

In Part I of this study, the in-hospital course of 219 patients who had undergone a cardiac operation is analyzed. Fever (greater than or equal to 37.8 degrees C, rectal) was present after postoperative day 6 in 159 patients (73%) and was of unexplained cause in 118. Fever decay in the population of unexplained fever patients was exponential. All patients with unexplained postoperative fever were afebrile by postoperative day 19. In-hospital pericardial rub and pleuritic chest pain, widening of the mediastinum on chest film, and pleural effusion were not specifically associated with unexplained postoperative fever. In Part II, 67 patients with unexplained postoperative fever were given indomethacin (100 mg per day) or placebo for 7 days by a randomized, double-blind protocol. Indomethacin resulted in a shorter duration of fever (2.4 vs 3.5 days, P is less than 0.01) and in a shorter duration of chest pain, malaise, and myalgias compared to placebo. Sixty-seven percent of the patients in Part I and all of the patients in Part II were contacted 2-8 months following hospital discharge. Five percent had experienced an illness that we considered to be acute pericarditis, but its occurrence was unrelated to whether the patient had had in-hospital unexplained postoperative fever, in-hospital rub or chest pain, or in-hospital administration of indomethacin.

Cardiac Surgical Procedures↗
PubMed1978

Mammographic patterns and risk of breast cancer.

A study of 171 breast cancer cases matched by age and race to asymptomatic controls was undertaken to check Wolfe's assertion [1, 2] that breast cancer risk depends strongly on the mammographic classifications N1, P1, P2, and DY. The classifications were made blindly relative to all variables, including the case-control factor. Distribution of the four categories among the breast cancer patients in this study was consistent with the distribution found by Wolfe. (P = .46). Our age-standardized risk ratio estimates of the categories, relative to N1, are 1.5 for P1, 2.7 for P2, and 7.2 for DY. While not as striking as Wolfe's estimates, the same monotone trend is evident, and the cases and controls differ significantly with respect to the distributions of the four categories (P less than .01).

Adult↗
PubMed1977

Hypertonic mannitol in the therapy of the acute respiratory distress syndrome.

Increased pulmonary artery pressure, an increase in pulmonary vascular resistance and an increase in physiologic dead space are consistent findings in patients with post-traumatic respiratory distress. Since mannitol has been shown to decrease renal vascular resistance following trauma, the effect of a bolus injection of 100 ml of 25% solution of this drug on pulmonary hemodynamics and physiologic dead space was investigated in 11 patients who had suffered multiple trauma. Five minutes after the injection, pulmonary vascular resistance fell (p less than .01), cardiac index increased (p less than .001) and physiologic dead space decreased (p less than .05). In contrast, the administration of 40 mg of furosemide produced no significant change in any of these parameters. Mannitol rapidly equilibrates in the extracellular space and exerts an osmotic effect across cell membranes. We postulate that the beneficial response to mannitol on the pulmonary vascular resistance and the improved perfusion of ventilated regions of the lung is due to a reduction in cell swelling and is not explainable by its diuretic effect. Improvement in the distribution of perfusion of pulmonary blood flow by mannitol may be a useful aid in the treatment of the post-traumatic form of the respiratory distress syndrome.

Acute Disease↗
PubMed1977

Uneven ventilation of the lung following trauma.

Ventilatory function of the lungs has been studied in 13 post-trauma patients using a two compartment analysis. The analysis is based upon a model of the lung which describes a nitrogen washout curve in terms of fast and slowly ventilated compartments. Data output from a digital computer provides values that compare the fractions of the alveolar ventilation and volume of the two compartments. All patients on initial investigation had large identifiable slow spaces. Subsequent evaluation at a time of clinical improvement showed that the ventilation of the slow space had increased significantly (P less than .003), whereas no change was evident in the volume fraction. The ventilation to volume ratio of the slow space, measured on these two separate occasions increased in twelve of the patients studied. An increase in this ratio correlated with improvement in the patient's clinical condition.

Adolescent↗
PubMed1976

Diversity among rabbit antibody light chain amino terminal sequences.

The amino terminal (positions 0 to 20) amino acid sequences of 22 rabbit antibody light chains are reported and compared with 44 amino terminal sequences previously described in the literature. Rabbit k light chains demonstrate three different amino terminal chain lengths and considerable variability at the amino terminal end. In relating amino terminal sequence to b locus allotype, allotype-specific residues (amino acid residues unique to all light chains having a given allotype) were not identified, although certain residue alternatives were unique to some of the b5 and b9 light chains. There was no correlation of antibody specificity with amino terminal sequence. In the most striking example, identical amino terminal sequences were associated with two different carbohydrate specificities (type VIII pneumococcal polysaccharide and streptococcal group A carbohydrate) and an aminophenyltrimethylammonium specificity. An obligatory association of amino terminal sequence with complete variable region framework sequences was not observed. Thus, it is not always possible to predict the framework homology among a given pair of light chains by examination of their amino terminal sequences. The limited diversity seen among the variable regions of murine myelomas that have the same antigen-binding properties is not found in the light chains of specifically elicited rabbit antibodies.

Amino Acid Sequence↗