Psychophysiologic aspects in essential hypertension

Epidemiologic and experimental studies disclosed that the sympathetic nervous system might play a pivotal role in the pathogenesis of essential hypertension. Although systolic pressure exhibits a weak endogenous rhythm, diurnal fluctuations of arterial pressure are provoked primarily by physical or emotional stress factors. The magnitude of the cardiovascular response, however, varies widely from individual to individual. Subjects at high risk of future hypertension,--such as those with a positive history of familial hypertension, high resting heart rate, or transient increase in arterial hypertension--revealed blood pressure hyperresponsiveness to stress stimuli mediated by an overreactivity of the sympathetic nervous system. Furthermore, cardiovascular reactivity to mental arithmetic tasks and to traffic noise put a patient at high risk of developing arterial hypertension. In women, exaggerated cardiovascular response to stress stimuli appeared to be mitigated by estrogens, whereas oral contraceptives overrode this 'protective' effect of estrogens. At a certain point, repeated episodes of high stress blood pressure could produce structural vascular changes finally inducing sustained hypertension.

Specificity of a cysteine proteinase of Entamoeba histolytica towards the alpha 1-CB2 peptide of bovine collagen type I

The cysteine proteinase of Entamoeba histolytica was shown to hydrolyze the cyanogen bromide peptide alpha 1-CB2 of calf skin collagen type I yielding two split products. Amino acid analyses of the formed peptides and estimation of the amino-terminal residues revealed that the alpha 1-CB2 peptide was exclusively cleaved between Gly10 and Leu11 within the sequence -Arg9-Gly10-Leu11-yielding two peptides with 7 and 29 amino acids, respectively. Under identical conditions the ratio of hydrolysis of the Gly10-Leu11 bond in the alpha 1-CB2 peptide to the Gly23-Phe24 bond within the internal sequence -Arg22-Gly23-Phe24- of bovine insulin B-chain was 100:65. The enzyme was found to split both benzyloxycarbonyl-Arg-Arg-methoxy-2-naphthylamide and benzyloxycarbonyl-Arg-Gly-2-naphthylamide. The ratio of hydrolysis of these substances was 100:11.6. Benzyloxycarbonyl-Gly-Arg-2-naphthylamide was a very poor substrate for the enzyme.

Hemodynamic abnormalities in borderline hypertension during mental stress

Cardiovascular reactivity to mental stress was studied in 41 male borderline hypertensives in comparison with 37 male normotensives of the same age. In addition to a higher near-basal blood pressure, the borderline hypertensive group showed stronger absolute and percentage increases of systolic and diastolic blood pressure during stress. The increases of heart rate and cardiac output and the decreases of total peripheral resistance were also greater in borderline hypertensives. Stroke volume showed a slight increase only in this group. The reaction of mean arterial pressure correlated in both groups with the increase of cardiac output. The relationship between the reactions of cardiac output and total peripheral resistance was high both in normotensives and borderline hypertensives, and the regression line in normotensives was shifted to the right in borderline hypertensives. The results indicate an increased integrated change of circulatory parameters during mental stress in borderline hypertension, with a dominantly stronger cardiac reaction. They underline the significance of an autonomic imbalance for the pathogenesis of borderline hypertension.

Long-term ambulatory treatment of metastatic colorectal adenocarcinoma by continuous intravenous infusion of 5-fluorouracil

To delineate the efficacy of continuous intravenous 5-fluorouracil (5-FU) infusion therapy for advanced colorectal adenocarcinoma, a study of 36 patients with measurable metastatic disease was conducted. Patients received a daily intravenous infusion of 300 mg/m2 5-FU over a 24-h period utilizing portable infusion devices and central venous catheters. In a population characterized by substantial pretreatment exposure to radiotherapy, chemotherapy, and other indicators of poor prognosis, 13/36 (36%) patients achieved an objective response. An additional 10/36 (28%) patients manifested stable disease (no change) and experienced survival comparable to that of patients with objective response. Toxicity was minimal; patients were able to continue 5-FU infusions 95% of the total time on protocol. There were no adverse hematologic effects or catheter complications. Because previously untreated patients benefited more frequently (positive response, 50%), continuous intravenous infusion should be evaluated further as a primary modality option when 5-fluorouracil antitumor chemotherapy is contemplated.