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Biomedical subjects

K D Bock

Publications and source records attributed to K D Bock.

At least 19 recordsLinked to original sources

Angioplasty of renal arteries: a report of ten year's experience.

Report of PTA of renal arteries in 288 patients. Primary results show good to optimal dilatation of the arteries (60.6% to 78.6%). One third of all cases achieved optimal blood pressures. In about 40% antihypertensive drugs had to be administered, in about 30% blood pressure remained unchanged although PTA was effective. PTA of renal arteries is the best method of treating renal hypertension, also because of the low rate of complications.

Angioplasty, Balloon

[General insecurity, "false" and "real" security: arguments for the routine study of hospital patients for anti-HIV].

HIV infection has become an important risk for medical personal. Use of sufficient preventive measures with all patients and patient materials is time consuming, expensive and impracticable. In the present epidemiological situation anti-HIV testing of all hospital patients will give correct information on the presence or absence of HIV infection for 999 of 1000 patients. In addition to the increased safety of medical personal, testing will have several other advantages, some for the HIV infected persons: (1) In patients with HIV-related diseases time consuming delays in diagnosing the disease can be avoided. An earlier start of therapy will improve prognosis. (2) In HIV-infected persons a therapy can be chosen which exerts the least stress to the immune system. This may delay manifestation or progression of HIV-related diseases. (3) By medical surveillance of HIV-infected persons prophylaxis and immediate therapy of opportunistic infections is possible, which may prolong survival time. (4) Counselling of persons previously unaware of their HIV infection will slow down spread of HIV in the population. (5) Missing data on prevalence and incidence of HIV infection in different geographical areas will be available. Apart from the considerable cost reduction by reducing the use of extensive preventive measures to less than 10% of patients, routine screening of all patients is already economic if testing of 10,000 patients will prevent one single new infection by counselling of people with previously unknown HIV infection.

AIDS Serodiagnosis

Alpha- and beta-adrenoceptors in hypertension. II. Platelet alpha 2- and lymphocyte beta 2-adrenoceptors in children of parents with essential hypertension. A model for the pathogenesis of the genetically determined hypertension.

To study whether changes in alpha- and beta-adrenoceptors in human essential hypertension (EHT) might be genetically determined, we assessed platelet alpha 2- and lymphocyte beta 2-adrenoceptor density in 48 normotensive children of normotensive parents (NT) and in 41 normotensive children with one EHT-parent. Both groups did not differ in age, body weight and height, blood pressure, heart rate, plasma catecholamine levels, plasma renin activity (PRA), and lymphocyte beta 2-adrenoceptor density. Platelet alpha 2-adrenoceptor density, however, was in EHT-children significantly higher than in NT-children. In NT-children, platelet alpha 2-adrenoceptors were significantly, inversely correlated with PRA, indicating that they might mirror renal alpha 2-adrenoceptors which inhibitorily regulate renin release. In contrast, in EHT-children PRA was not at all related to platelet alpha 2-adrenoceptors, suggesting an early (even in the normotensive stage) disturbance of the alpha 2-adrenoceptor-mediated regulation in renin release. From these results and those obtained in the experimental rat models of acquired hypertension, a model for the pathogenesis of the genetically determined hypertension is proposed in which a very early step in the development of hypertension is a genetically determined increase in renal alpha-adrenoceptors that causes enhanced sodium retention. This initiates a chain of events that finally results in increased peripheral vascular resistance and, hence, blood pressure. On the other hand, beta-adrenoceptor changes seem to be secondary phenomena due to the elevation in blood pressure.

Adolescent

Intraperitoneal heparin in peritoneal dialysis and its effect on fibrinopeptide A in plasma and dialysate.

In 6 patients on continuous ambulatory peritoneal dialysis we investigated the inhibition of intraperitoneal fibrin formation by heparin. A continuous addition of 500 U of heparin per liter dialysate was used for 52 h. In plasma no heparin activity could be detected, even 52 h after intraperitoneal administration of heparin. The fibrin formation was determined by fibrinopeptide A, a thrombin-induced split product of fibrinogen. In patients under regular continuous ambulatory peritoneal dialysis we determined the fibrinopeptide A concentrations in plasma. The values were comparable with the fibrinopeptide A concentrations measured in disseminated intravascular coagulopathy. They decreased during intraperitoneal administration of heparin from 63.2 +/- 11.8 to 4.9 +/- 1.7 ng/ml. The fibrinopeptide A concentration in the 4-hour intraperitoneal dialysate (155.8 +/- 15.7 ng/ml) decreased after heparin administration to 8.5 +/- 2.0 ng/ml and was always higher than in plasma. We conclude that 500 U heparin per liter dialysate prevents the intraperitoneal fibrin formation. The low antithrombin III concentration (0.44 +/- 0.13 mg/dl) in protein-poor dialysate seems to be sufficient to inhibit the thrombin activity after acceleration by heparin.

Ascitic Fluid

Changing prescription patterns: impact on costs.

The cost of treating hypertension is high. In the Federal Republic of Germany the total sales of antihypertensive compounds increased, from 1981 to 1984, from 1075 million to 1525 million DM per year, corresponding to 7.4 and 9.1%, respectively, of total drug expenditure. Economists have calculated that about two-thirds of this increase is caused by structural changes within the market, i.e. changing prescription patterns. The proportion of prescribed daily doses of reserpine combinations dropped from 52 to 34% whereas that of most other compounds increased. The approximate daily costs of treatment vary from 0.5 DM (reserpine combinations) to 2.5 DM [angiotensin converting enzyme, (ACE) inhibitors], but the decline of the cheaper compounds and their substitution by newer and more expensive drugs has resulted in additional costs of 309-328 million DM. The higher prices of the new drugs should be justified by greater benefits compared with conventional compounds. Assessment of new antihypertensive drugs should include potency, efficacy, number and quality of adverse effects, and impact on quality of life. The evaluation should be performed separately for mild and for more severe forms of hypertension. Some advantages or drawbacks of the newer drugs may be important for small subgroups only.

Antihypertensive Agents

Urinary enzyme excretion after a single dose of phenacetin and paracetamol (acetaminophen) during antidiuresis and during water diuresis.

2 g phenacetin or paracetamol in a single oral dose were administered to five healthy persons under the conditions of antidiuresis and subsequent water diuresis. Excretion of the brush border enzyme GGT, the cytoplasm enzyme LDH, and the lysosomal enzymes, NAG and GAL, was analysed before, during and after ingestion of the analgesics. Increased excretion of LDH and GGT indicated a similar moderate damage of the tubular epithelia after phenacetin and paracetamol. The state of diuresis appeared to have no influence.

Acetaminophen

[Factitious disease. Observations on 44 cases at a medical clinic and recommendation for a subclassification].

From 1971 to 1985, 44 cases of self-induced factitious disorders were observed in the Medical Department of a University Hospital. The diseases were often severe, one patient even died. The various symptoms and diseases presented by the patients, the methods of producing them, and the diagnostic and therapeutic aspects of these cases are described. Patients were analysed with regard to age, sex, profession, psychosocial adaptation, number and duration of hospitalisations, presentation of complaints, behaviour on the ward, relation to the doctor, self-destructive tendencies, readiness to suffer and possible motivations. According to the criteria of the DSM-III, seven patients were malingerers (DSM-III: V 65.20) and 37 had a "chronic factitious disorder with physical symptoms" (DSM-III: 301.51). However, the findings in the patients of the latter group strongly suggest that they form an extremely heterogeneous population. Therefore we propose a subclassification of the DSM-III category 301.51 as follows: Type A. Muenchausen syndrome in the proper sense; dramatic deception of mainly acute illness; pseudologia fantastica; social maladaptation, chaotic life situations; many, mostly short hospitalisations; many interventions; at first well adapted, later hostile; mostly men. Type B. Self-induced, mainly chronic illness; behaviour adequate, highly compliant; often little emotion, contrasting with the sometimes severe illness; socially adapted; history remarkably blank with regard to psychosocial stress; several often longlasting hospitalisations and many interventions; almost exclusively younger women from (para-)-medical professions. Type C. Willfull interference with the healing of wounds, cutaneous ulcers, abscesses or dermatological artefacts; history with marked personal losses or severe chronic medical problems; at first well adapted, later hostile, passive/aggressive; women prevail. A conversion syndrome (DSM-III: 300.11) was not observed. In contrast to malingering, the basis of the disorder in types A, B and C is unconscious in origin, thus similar to the conversion syndrome. Contrary to the latter, however, the production of physical symptoms is under voluntary control. The proposed subclassification represents a hypothesis for testing which might facilitate the analysis of the basic personality disorder, so far lacking. The investigation of the psychopathology of these patients and their treatment is difficult if not impossible because most refuse psychiatric exploration and therapy. Consequently follow-up studies and data on the prognosis are rare.

Adolescent

Differential changes in lymphocyte beta 2-adrenoceptor density by beta-blocker administration: role of intrinsic sympathomimetic activity.

To study the role of intrinsic sympathomimetic activity (ISA) in beta-blocker-induced changes of beta-adrenoceptors, the effects of administration of several beta-blockers for 9 days on lymphocyte beta 2-adrenoceptor density--assessed by 125iodocyanopindolol binding--were investigated in 47 normotensive volunteers. Propranolol (unselective; no ISA; 4 X 40 mg/day) increased beta 2-adrenoceptor density by 25-40%; after withdrawal beta 2-adrenoceptor density declined slowly, being still elevated for 3 days. In contrast, the unselective beta-blockers pindolol (ISA (isoprenaline = 1.0) = 0.39; 2 X 5 mg/day) and mepindolol (ISA = 0.27; 2 X 5 mg/day) decreased beta 2-adrenoceptor density by 50% and 35%, respectively, while alprenolol with weak ISA (=0.066; 4 X 100 mg/day) had no effect. Among the beta 1-selective blockers studied, celiprolol with ISA (=0.32; 1 X 200 mg/day) decreased beta 2-adrenoceptor density by 30% whereas bisoprolol without ISA (1 X 10 mg/day) had no effect. It is concluded that the ISA determines the direction and amount of beta-adrenoceptor alterations induced by beta-blockers. Furthermore, changes in human lymphocyte beta-adrenoceptors reflect subtype-selective changes in beta 2-adrenoceptors, since the beta 1-selective blocker bisoprolol without ISA--in contrast to propranolol--did not affect lymphocyte beta 2-adrenoceptors. Accordingly, the fact that the beta 1-selective blocker celiprolol with ISA decreased lymphocyte beta 2-adrenoceptors, is consistent with the hypothesis that celiprolol possesses in addition to its beta 1-antagonistic activity a beta 2-agonistic activity.

Adrenergic beta-Antagonists

Intraperitoneal fibrin-formation and its inhibition in CAPD.

The intraperitoneal fibrin formation and its inhibition by intraperitoneal heparin (5000 U) was investigated in six patients on CAPD. The intraperitoneal heparin concentration decreased linearily from 1.78 U/ml to 1.13 U/ml during a 4-hour dwell time. The antithrombin III-concentration increased to 0.56 +/- 0.1 mg/dl, reaching 1.87% of normal plasma values. The antithrombin III-portion of total protein was 0.62% in plasma and 0.79% in dialysate. The fibrinopeptide A-concentration, a specific product of thrombin action on fibrinogen was 37.1 +/- 11.8 ng/ml in plasma (normal range: less than 2.5 ng/ml) and 153.4 +/- 16.8 ng/ml in dialysate during regular CAPD. After the addition of 5000 U heparin the fibrinopeptide A-concentration in dialysate decreased to 11.6 +/- 2.6 ng/ml during a 4-hour dwell time. In vitro experiments showed no remarkable inhibition of fibrin formation by heparin without antithrombin III in dialysate. We suggest that the fibrinopeptide A is produced intraperitoneally and the antithrombin III-concentration in dialysate is sufficient to inhibit the fibrin formation after acceleration by heparin.

Antithrombin III

Alpha- and beta-adrenoceptors in circulating blood cells of essential hypertensive patients: increased receptor density and responsiveness.

In 40 male patients with established essential hypertension (P diast greater than 95 mmHg) platelet alpha 2-adrenoceptor density (by 3H-yohimbine binding) and -responsiveness (by adrenaline-induced aggregation) as well as lymphocyte beta 2-adrenoceptor density (by (+/-)-125 iodocyanopindolol binding) and -responsiveness (by cyclic AMP responses to isoprenaline) were determined and compared with those in 40 male age-matched normotensives (P diast less than 90 mmHg). In essential hypertensive patients mean platelet alpha 2- and lymphocyte beta 2-adrenoceptor densities were significantly increased. When data from all 80 subjects were combined, significant positive correlations between mean arterial blood pressure and alpha 2- and beta 2-adrenoceptor densities, respectively, were found. The increases in alpha 2- and beta 2-adrenoceptor densities were accompanied by enhanced responsiveness to adrenergic stimulation: in platelets adrenaline-induced aggregation--via alpha 2-adrenoceptor stimulation--was exaggerated, and in lymphocytes isoprenaline produced significantly greater increases in the intracellular level of cyclic AMP. It is concluded that the increased density and responsiveness of alpha 2-and beta 2-adrenoceptors in circulating blood cells of essential hypertensive patients may reflect increased sympathetic activity, which might contribute to the elevation of blood pressure.

Adenylyl Cyclases

Acute regulation of lymphocyte beta 2-adrenoceptors is altered in patients with essential hypertension.

The effects of acute stimulation of the sympathetic activity by dynamic exercise on lymphocyte beta 2-adrenoceptor density [assessed by (-)-125iodocyanopindolol (ICYP) binding] and responsiveness [10 mumol/l isoprenaline-induced cyclic adenosine monophosphate (cAMP) increases] were studied in 10 normotensive (Pdiast < 90 mmHg) volunteers and in 10 patients with established essential hypertension (Pdiast > 95 mmHg). In normotensives, dynamic exercise on a bicycle (80% of maximum heart rate) for 15 min led to an increase in lymphocyte beta 2-adrenoceptor density from 1080 +/- 77 to 2033 +/- 152 ICYP binding sites/cell; concomitantly isoprenaline-induced increase in lymphocyte cAMP was enhanced. This effect appears to be mediated by beta 2-adrenoceptor stimulation, since the exercise-induced increase in beta 2-adrenoceptor density was markedly attenuated by pretreatment of the volunteers with propranolol (5 mg intravenously 45 min before exercise), but not by pretreatment with the beta 1-selective antagonist bisoprolol (2.5 mg intravenously 30 min before exercise). In patients with essential hypertension, lymphocyte beta 2-adrenoceptor density (1512 +/- 101 ICYP binding sites/cell) was significantly higher than in controls (P < 0.05); the same held true for isoprenaline-induced cAMP increases. In these patients, however, dynamic exercise caused only a slight increase in lymphocyte beta 2-adrenoceptor density (to 1859 +/- 154 ICYP binding sites/cell) and in isoprenaline-induced cAMP increases. From these results it is concluded that in essential hypertension acute regulation of the beta-adrenoceptor/adenylate cyclase system is impaired.

Adult