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Biomedical subjects

H Friedrich

Publications and source records attributed to H Friedrich.

At least 37 records · Page 2Linked to original sources
PubMed1992

Trichloroharmanes as potential endogenously formed inducers of Morbus Parkinson: synthesis, analytics, and first in vivo-investigations.

The hypnotic chloral reacts chemically with tryptamine and tryptophan under physiological conditions to give novel trichloro-tetrahydroharmanes ("TTHs"). These are structurally similar to the classical neurotoxin MPTP. Moreover, the TTH-precursor chloral is also a metabolite of the frequently used solvent trichloroethylene (Tri). These properties and first hints at a neuropharmacological potential of this class of substances warrent investigations whether TTHs and other chloral-derived harmanes are formed endogenously and possibly have to do with the pathogenesis of Morbus Parkinson (MP). For an investigation of these problems, some fundamental methods and results had to be elaborated first: the synthesis of several representatives of this novel class of trichloroharmanes, sensitive analytical methods for the detection of these compounds even in biological matrices, and studies concerning their biological "fate".

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

Endogenous Alkaloids in Man - Synthesis, Analytics, in vivo Identification, and Medicinal Importance*,1.

The IN VITRO and IN VIVO condensation of endogenous (or administered) reactive amines and carbonyl compounds is reported, leading to alkaloid-type heterocycles. The spectrum of the presented "mammalian alkaloids" ranges from isoquinoline derivatives, via beta-carbolines, through to thiazolidines, arising from vitamin B (6), chloral, and glyoxylic acid, respectively. Formation of these compounds may occur accidentally, but might also be induced intentionally, as a therapy for metabolic diseases.

Journal Article↗
PubMed1991

[Value of non-plethysmographic methods in determining airway resistance].

To examine whether the complicated method of body plethysmography can be replaced by non-plethysmographic methods, such as oscilloresistometry (Ros), the closing pressure method (Run) or the forced expiration volume method (FEV1), the authors studied the results obtained with 247 hospitalised patients between 18 and 81 years of age suffering from, or free from, airway obstruction. Although satisfactory correlations were obtained by linear and curvilinear regression analysis, considerable differences were seen in individual patients suffering from obstructions to a higher degree. Oscilloresistometry showed at the standard value limit of the airway resistance applicable in body plethysmography (0.30 kPa/l/s) a sensitivity of 89%, whereas the specificity was only 62%. Almost identical values of sensitivity (92%) and specificity (61%) were attained by the closing pressure method only if the standard value limit was set a little higher, namely, at 0.35 kPa/l/s. FEV1, which is easiest to measure, was able to objectivate an airway obstruction in a manner comparable to that of Ros and Run; there was in fact even a closer statistical correlation between the body plethysmographic resistance mographic methods are suitable for screening examinations on account of their sensitivity. However, if the results on the examination are not in keeping with the overall clinical findings, further diagnostic clarification must be sought by performing a body plethysmographic measurement.

Adolescent↗
PubMed1991

Endogenous alkaloids in man--synthesis, analytics, in vivo identification, and medicinal importance.

The in vitro and in vivo condensation of endogenous (or administered) reactive amines and carbonyl compounds is reported, leading to alkaloid-type heterocycles. The spectrum of the presented "mammalian alkaloids" ranges from isoquinoline derivatives, via beta-carbolines, through to thiazolidines, arising from vitamin B6, chloral, and glyoxylic acid, respectively. Formation of these compounds may occur accidentally, but might also be induced intentionally, as a therapy for metabolic diseases.

Alkaloids↗
PubMed1990

Intramedullary vascular lesions in the high cervical region: transoral and dorsal surgical approach. Two case reports.

Intramedullary vascular malformations in the high cervical region are extremely rare. Two young adult patients with vascular lesions at the level C 2 and 3, and C 2-4 are reported. In one patient selective spinal angiography revealed a combined malformation with a ventral intramedullary arteriovenous angioma and a premedullary aneurysm. This malformation was approached and removed transorally after spondylectomy of C 2. In the second patient MRI and selective angiography showed an intramedullary hemangioblastoma extending from C 2-C 4. After embolization, this lesion was surgically removed via a dorsal approach. Both patients suffered from severe neurological deficits preoperatively. MRI and selective angiography showed the exact locations of the tumors within the spinal cord and indicated a transoral approach in one case and a dorsal approach in the other. After complete obliteration and removal of the lesions, the patients showed no neurological deficits and returned to their previous professions.

Adult↗
PubMed1990

[Results of intervertebral disk surgery in advanced age].

Among 2983 patients operated upon for herniated lumbar disks from 1981 through 1985 193 were between 65 and 84 years of age. Many of them had long-standing histories of recurrent sciatica. Most patients presented with unilateral or bilateral radicular pain, motor weakness or paresis and typical sensory changes. The usual type of conservative treatment had been tried in all patients before operation was recommended. Although our patients were, due to their advanced age and medical problems less than optimal surgical risks, we did not encounter a single perioperative mortality and postoperative complications were limited. The mean duration of hospitalisation was 15.1 days. Surgical results were quite encouraging, since 80.3% of the patients reported satisfactory resolution of their preoperative pain, motor weakness and sensory changes. Since most patients can achieve relief of their preoperative pain, it is not justified to restrict operative treatment only because of advanced age despite a number of preoperative risk factors.

Aged↗
PubMed1990

[Sonographic diagnosis of gastroesophageal reflux in infancy].

The gastroesophageal reflux is a common problem in the pediatric clinical practice in the 1st year of life. Its diagnosis is mainly based on the x-ray and the measurement of the esophageal pH. Our investigation shows the possibility of the ultrasonographical diagnosis of this disturbance. We could demonstrate a good correlation between the x-ray and the ultrasonographical findings. A continuous lasting gastroesophageal reflux which takes more than 5 minutes points to a pathologic reflux pattern with the well known complications. Thus, ultrasonographical investigation should perform before an extensive diagnostic is taken into consideration.

Esophagus↗
PubMed1989

[Status of the captopril test in the diagnosis of hypertension].

The place of captopril (C) testing in the screening for renovascular hypertension is still controversial. Baseline and C-stimulated plasma renin concentrations (PRC) were measured in 113 hypertensives, who where referred for the exclusion of secondary hypertension. In addition intravenous digital subtraction angiography (DSA) and a renal scintigraphy were performed. When renal artery disease was revealed by DSA or renin was stimulated the renal arteries were visualized by direct arteriography (and treated by angioplasty if possible). 86 patients underwent each diagnostic test: 21% had renovascular hypertension. Unilateral renal artery stenosis (n = 10) was detected by the captopril test (cutoff values: baseline greater than 40 microU/ml, after C greater than 180 microU/ml, sensitivity 100%). Bilateral renal artery stenosis (n = 8) was missed when the disease was equally severe on either side (sensitivity 50%). The specificity of C testing was 82%, overall sensitivity (uni- and bilateral disease 78%, prevalence 21%, predictive value of the positive test 0.56, predictive value of the negative test 0.93). With i.v.-DSA the renal arteries were technically evaluable in 91% (82/92) of cases. The sensitivity for the detection of all renal artery stenoses was 79% (uni-lateral 100%, bilateral 40%, specificity 97%). The sensitivity of renal scintigraphy for the detection of unilateral renal artery stenoses was 50%, for the detection of bilateral renal artery stenoses 43%, specificity 81%. The present study demonstrates the usefulness of captopril for the detection of unilateral renal artery stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Man systems aspects in the design concept of the Columbus Man-Tended Free-Flyer (MTFF).

The Man-Tended Free-Flyer (MTFF) of the European Space Agency's COLUMBUS Program is a free flying pressurized laboratory in which payload processes will be performed in an automatic mode, i.e. without presence of man. Payload servicing as well as spacecraft servicing will be conducted by man i.e. when man-tended. The paper describes the effect of the temporary presence of man on the MTFF design concept, the requirements concerning functions, safety and redundancy of the vital spacecraft subsystems and the work environment for the astronauts. A next step is manned activities in space is an extended combined MTFF/HERMES Mission where, in addition to MTFF servicing, payload processing will be conducted in the MTFF, involving the HERMES crew. Man systems aspects of the MTFF for this extended mission will be addressed. In a growth scenario towards European's permanent presence of man in space, the MTFF is intended to represent a building block for an European Station. The effect of the growth requirement for the MTFF of supporting permanent manned operation will be described. The COLUMBUS Program also includes a Pressurized Laboratory Module which will be attached to the US-International Space Station (ISS). Similarities between that Module and the MTFF related to Man Systems aspects will be shown.

Equipment Design↗
PubMed1988

[Illness and threat. Forms of psychosocial coping in multiple sclerosis].

The onset of a chronic illness is synonymous with a massive breach in the stability and routine in the daily life of the patient. These individuals are thus confronted with the task of integrating the illness and its consequences into their lives in a manner that, despite and with the illness, will allow them to live as normal life as possible. Multiple Sclerosis, however, presents specific problems in the sense that it is chronic illness with uncertain prognosis whose course can neither be predicted nor influenced. The question as to how and how successfully the chronically ill cope with MS is pursued in this paper, focusing on a group of 60 MS-patients over a period of five years following diagnosis. Both the individual coping patterns as well as the occupational situation and the forms of mutual coping in the family or partner relationship are considered. These factors are decisive in determining the significance of the illness in the lives of all those involved and whether it will be possible to deal with the more grave forms of MS and their psychosocial consequences in a flexible manner.

Adaptation, Psychological↗
PubMed1987

Evoked muscle action potentials from regenerated rat tibial and peroneal nerves: synthetic versus autologous interfascicular grafts.

To compare peripheral nerve regeneration across bridging synthetic tubular implants with ordinary autologous transplantation, we recorded evoked muscle action potentials 3 months after transection, following direct stimulation of rat tibial and peroneal nerves. Significantly, with autologous transplantation we were able to evoke compound muscle action potentials in all but one case (this having a 15-mm gap). Pooling the groups together, compound action potentials could be recorded in 15 of 45 cases that had regenerated through 13- to 16-mm gaps. Potentials in the synthetic implant-treated group tended to show more temporal "scattering" in the late phases of the EMG response. No differences were found in compound muscle action potential amplitudes and duration, or terminal motor conduction velocity, between both experimental groups, between different artificial tubuli, between different gap lengths, or between the peroneal and tibial nerves. The overall values were remarkably lower than in nontransected controls, about 25% of the compound muscle action potential normal amplitude voltage and 60% of the terminal motor conduction velocity.

Action Potentials↗
PubMed1987

Nerve regeneration in synthetic and autogenous interfascicular grafts. II. Morphometric analysis.

Cross-sectional areas at different levels, number of axons, maximal diameters, and number and maximal diameters of vessels were measured comparing autologous transplants with synthetic implants and nonlesion controls in a rat nerve regeneration model. The corresponding electrophysiologic data have been reported earlier in this journal. Although similar in many aspects, transplants led to the overall more reliable and slightly superior results, still lacking a substantial percentage of numerical qualities found in normal nerve, at least within the 3-month regeneration in this study.

Animals↗