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Biomedical subjects

G Heine

Publications and source records attributed to G Heine.

At least 19 recordsLinked to original sources
PubMed1993

Responses of fatigable and fatigue-resistant fibres of rabbit muscle to low-frequency stimulation.

This study investigates early adaptive responses of fast-twitch muscle to increased contractile activity by low-frequency stimulation. Changes in metabolite levels and activities of regulatory enzymes of carbohydrate metabolism were investigated in rabbit tibialis anterior muscle after 24 h of stimulation. In addition, changes elicited during a 5-min lasting acute stimulation experiment were compared between 24-h-prestimulated and contralateral control muscles. Stimulation for 5 min reduced energy-rich phosphates and glycogen, and increased lactate in the control muscle. A transient elevation of fructose 2,6-bisphosphate demonstrated that activation of phosphofructokinase 2 was an immediate response to contractile activity. Prestimulated muscles displayed nearly normal values for ATP, phosphocreatine and glycogen, and did not augment lactate. Increased activities of hexokinase and phosphofructokinase 2 and permanently elevated levels of fructose 2,6-bisphosphate pointed to enhanced glycolysis with glucose as the main fuel in the prestimulated muscle. Isometric tension of the control muscle decreased rapidly a few minutes after the onset of stimulation. In the prestimulated muscles, tension was almost stable, but amounted to only 30%-40% of the initial tension of the control muscle. In view of the fibre type distribution of rabbit tibialis anterior, these findings suggested that a large fibre fraction of the prestimulated muscle, possibly the glycolytic type IID fibres, did not contract. Therefore, the possibility must be considered that the metabolite pattern of the 24-h-stimulated muscle primarily reflected metabolic activities of the contracting, less fatigable fibres, most likely type IIA and type I fibres.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

Modulith SL 10/20--experimental introduction and first clinical experience with a new interdisciplinary lithotriptor.

More than 20 second-generation lithotriptors have been introduced for extracorporeal shock-wave lithotripsy. Despite great technical progress, each machine still has its specific short-comings. In cooperation, Storz Medical (Kreuzlingen, Switzerland) and the Department of Urology (Klinikum Mannheim, FRG), have developed a new lithotriptor designed to overcome these drawbacks. Energy source: Electromagnetic cylinder with paraboloid reflector (40 cm) for focusing, providing a wide range of pressure (190-1,000 bar) and a focal zone of 28 x 6 mm. The focal depth is maximally 15 cm. Coupling and positioning: Water cushion with patient lying on a specially designed 'acoustic cradle' consisting of an impedance-adapted foil. This is integrated in either a manually or automatically operated table. Localization: Coaxial ultrasound probe for real-time scanning and integrated C arm with pulsed fluoroscopy using a virtual focus (moved along x-axis) for stone localization. In 1989, we commenced with the first treatment based on our own in vitro and in vivo studies to determine the range of energy required for safe application. We treated 137 stones (100 caliceal, 19 pelvic and 18 ureteral) in 88 patients. The mean generator voltage was 16 kV (10-18 kV). Successful disintegration was achieved in 83 patients (95%) employing an average of 2,359 impulses (940-3,500). Thirteen percent of the treatments were performed without any anesthesia on lower generator voltage (10-15 kV), whereas the majority of calculi were treated under intravenous analgesia. The 5 failure cases included 2 stones in a caliceal diverticulum. Moreover, 12 patients with biliary calculi (11 gallstones and 1 bile duct stone) were successfully treated; 1 of these cases required a second treatment session.

Animals↗
PubMed1988

Biological effects of shock waves: kidney haemorrhage by shock waves in dogs--administration rate dependence.

The effect of shock waves on normal canine kidneys was examined in two groups of dogs whose right kidneys were exposed to 3000 shock waves generated with 20 kV and 40 nF in a Dornier HM II lithotripter. The groups differed only in the rate of shock wave administration which was 100 and 1 per second, respectively. Autopsy was performed 24 to 30 h later. Macroscopically and histologically, significantly more haemorrhages occurred in the kidney parenchyma if shock waves were administered at a rate of 100 waves per second. Haemorrhages were diffuse, the outer medulla was most heavily affected. The results show that kidney damage is dependent on the rate of shock wave administration. They argue against a direct shock wave effect and favor cavitation as the mechanism of shock wave damage although thermal effects cannot be excluded.

Animals↗
PubMed1987

Biological effects of shock waves: lung hemorrhage by shock waves in dogs--pressure dependence.

The most serious side effect observed during the destruction of gallstones by shock waves in dogs was lung bleeding. To determine the conditions leading to lung damage, pressure probes were implanted into dogs between the lung and the diaphragm. The distance between the lung and the focal point of the pressure field was determined at which 1000 shock waves caused no more lung hemorrhage. On the long axis it is greater than 15 cm and perpendicular to the long axis it is 4 cm. Shock wave pressures over 2 MPa could be administered safely, whereas a pressure of 10 MPa caused bleedings in beagles, but probably not in boxers.

Animals↗
PubMed1982

[Alveolar differentiation in rabbits].

Lung tissue of the white New Zealand rabbit was examined by transmission and scanning electron microscopy from the 23rd to the 30th day post conception (p.c.). The following results were obtained: 1. About day 23 p.c., when the development of capillaries increases, the "canalicular period" starts. This is followed by the "terminal sac period" characterized by the beginning of alveolarisation. On day 28 p.c. typical alveoles can be found. 2. The Pneumoplast is the stem cell of the pneumocyte type I as well as type II. They differentiate parallel in either one or the other. This stem cell of the entodermal origin has a single cilium. During the period of single cilia growth the cell is not mitotic. 3. The maturation of the lamellar body, typical of the pneumocyte type II, can be accomplished in a direct as well as in a indirect way of synthesis. Transitions between both are possible. 4. The most important factors of differentiation are collagenic induction substances beside nerval and humoral factors. Those humoral factors can be transported easier into the cells with advancing capillarisation as a result of the shortened distance of diffusion.

Animals↗
PubMedDate not supplied

[Modulit SL-20. Its development and clinical trial].

Modulit SZ-20 represents the third lithotriptor generation comprising the advantages of high disintegration efficacy, operation without anesthesia, combined system of ultrasonic and fluoroscopic localization of the concrements, provision with multifunctional platform. The impulse is generated by a cylindrical electromagnetic spiral with a paraboloid reflector. The waves go through a water cushion and impedance-adapted layer in which the patient is placed. Localization of the concrements is conducted by a special ultrasonic detector operating on-line, or fluoroscopically by an integrated arm C of the x-ray unit. In vitro and animal experiments have given evidence for high efficacy of the above lithotriptor, make it possible to evaluate dose-related and reversible renal trauma, to compare similar traumas induced by other lithotriptors. Since 1988 Modulit-SZ-20 has been tested for localization of nephroliths and ureteroliths. Then the attention of the designers was focused on concrement disintegration. After improving the X-ray guidance, the voltage of the generator, analysis of the experience gained, the percentage of disintegration has risen to 94. The authors achieved completed disappearance of the stones in 88% of their patients. SZ-20 Modulit proved effective against choleliths and stones in the biliary ducts as well. This device is recommended as high effective stone-crushing modality of the third generation.

Animals↗