Biomedical subjects
Publications and source records attributed to E Hagen.
The possibility of connections between Canalis mastoideus and Cellulae mastoideae is checked by means of probation in 30 human skulls and 10 selected skulls (out of this 30) by x-ray investigation. In 4 cases such connection were seen. It is evident that the migration of inflammations along such connections is possible.
The ultrastructure of the rabbit retinal nerve fibre layer was studied both in retinal centre and periphery. The central nerve fibre layer was found to contain large masses of--mostly myelinated--nerve fibres, somata and processes of astrocytes and oligodendrocytes, vitreal processes of Müller cells, and blood vessels. Astrocyte and Müller cell processes could be discriminated both by their direction and by the thickness of their intermediate filaments which was about 7 nm in Müller cells and about 10 nm in astrocytes. Some peculiarities of nuclei and cytoplasmic organelles of rabbit retinal astrocytes and oligodendrocytes are described. Myelin sheaths are demonstrated to be derived from oligodendrocytes; in some cases, two axons were found within a common myelin sheath. In the retinal periphery, only sparse thin bundles of unmyelinated axons were found in between a thick row of big Müller cell endfeet; astrocytes, oligodendrocytes, and blood vessels were missing here. In both retinal regions, node-like membrane specializations of optic axons were found; these were always surrounded by a corona of fine glial processes arising from astrocytes as well as from Müller cells. The features of myelination within the rabbit nerve fibre layer were quantified, and compared with recent literature data. A hypothesis is offered relating the production of myelin to the release of diffusable substance(s) by active axons. This hypotheses allows to account for the striking finding that relatively thick axons remain unmyelinated in the nerve fibre layer of most mammalian retinae like in the rabbit retinal periphery whereas they become myelinated in the central rabbit retina like in central nervous system in general.
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The modified Azan-staining technique improves the visibility of some histological structures. In this way it is more easy to take dates in morphometrical investigation especially to determine the nuclear-plasma-relation.
The acute hemodynamic and hormonal effects of the oral angiotensin-converting enzyme (ACE) inhibitor lisinopril (MK-521) were assessed over a period of 96 hours in 12 patients with heart failure. This compound is the lysine analogue of enalaprilat (MK-422), is biologically active following absorption, and is cleared via the urine without any known metabolic transformation. Single doses of lisinopril, ranging from 1.25 mg to 10 mg, were administered on days 1 and 3, each followed by 48 hours of intensive hemodynamic observation. Across all doses, maximal reductions in mean arterial pressure (17.2%), mean pulmonary capillary wedge pressure (28%), and systemic vascular resistance (25.6%) were observed compared to baseline values. No significant changes in heart rate were recorded. Arterial blood was sampled at frequent intervals for angiotensin II, ACE activity, plasma renin activity, renin substrate, plasma aldosterone, and serum drug levels. Right atrial blood was sampled simultaneously for angiotensin I, thus permitting assessment of the degree of pulmonary conversion to angiotensin II. The results indicate potent inhibition of the renin-angiotensin-aldosterone system along with hemodynamic efficacy over a period exceeding 24 hours. Frequent clinical follow-up on long-term chronic therapy has revealed no adverse experience.
The effect of progressive increases in ventilator rate on delivered tidal and minute volumes, and the effect of changing peak inspiratory pressure (Pmax), positive end-expiratory pressure (PEEP), and inspiration to expiration (I:E) ratio at different ventilator rates were examined. Five different continuous-flow, time-cycled, pressure-preset infant ventilators were studied using a pneumotachograph, an airway pressure monitor, and a lung simulator. As rates increased from 10 to 150 breaths per minute, tidal volume stayed constant until 25 to 30 breaths per minute; then progressively decreased. In all, tidal volume began to decrease when proximal airway pressure waves lost inspiratory pressure plateaus. As rates increased, minute volume increased until 75 breaths per minute, then leveled off, then decreased. Substituting helium for O2 increased the ventilator rate at which this minute volume plateau effect occurred. Increasing peak inspiratory pressure consistently increased tidal volume. Increasing positive end-expiratory pressure decreased tidal volume. At rates less than 75 breaths per minute, inspiratory time (inspiration to expiration ratio) had little effect on delivered volume. At rates greater than 75 breaths per minute, inspiratory time became an important determinant of minute volume. For any given combination of lung compliance and airway resistance: there is a maximum ventilator rate beyond which tidal volume progressively decreases and another maximum ventilator rate beyond which minute volume progressively decreases; at slower rates, delivered volumes are determined primarily by changes in proximal airway pressures; at very rapid rates, inspiratory time becomes a key determinant of delivered volume.
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The recent discovery of an antigenic component of the causative agent of Non-A, Non-B hepatitis, has led to the characterization of this virus--Hepatitis C Virus (HCV)--and to the identification of an antibody present in infected subjects (anti-HCV) detected by means of the C-100 antigen derived from a nonstructural region of the viral genome. Using a commercial Kit (Ortho Diagnostic Inc.), the incidence of anti-HCV antibody was studied in the Military Hospital "Dr. Carlos Arvelo" of Caracas, Venezuela with the following results: Health personnel (doctors, nurses, laboratory staff): 102 persons studied, 2 positives (1.96%); 16 patients in chronic hemodialysis: 6 positives (33%); 20 subjects with antibodies against HIV virus, confirmed by Western Blot: 7 positives (35.4%). Of 10 patients with Surface Antigen negative Chronic Hepatitis, 7 (70%) positive for anti-HCV, of 25 patients with cirrhosis: 12 positive (48%), 2 patients with hepatocarcinoma 1 positive (50%). There was also a high incidence of total anti-core antibodies in the patients studied. The results suggest that the hepatitis C virus could be playing an important role as a causative factor of liver diseases in our Country.