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Biomedical subjects

P Hoffmann

Publications and source records attributed to P Hoffmann.

At least 199 records · Page 11Linked to original sources
PubMed1989

[Thoracic peridural anesthesia in childhood].

Local and regional anesthesia, especially peridural anesthesia, is a rarely used method in pediatric anesthesia. That cannot be explained by children's physis, since it shows in general neither a different margin of therapeutic safety nor a different effect/side-effect ratio than in adult. Nevertheless, psychologic alteration of children through operation and anesthesia necessitate simultaneous endotracheal narcosis during peridural anesthesia. The following characteristics of regional anesthesia in children should be regarded: The younger the child the higher is the ratio between extracellular water and body weight. Thus higher doses of local anesthetics in relation to body weight can be applied. The smaller diameters of children's nerves support diffusion of local anesthetics and, therefore, allow the use of lower concentrations. Increased perfusion of tissues and high cardiac output lead to rapid resorption and accelerated increase of anesthetic blood levels. This disadvantage can be avoided by use of lower concentrations of anesthetics. Even an extended sympathetic block during peridural anesthesia hardly causes any negative effect on circulatory parameters. We performed thoracic epidural anesthesia during thoracic and upper abdominal surgery in 40 5-15-year-old children. In many of the patients additional risks had already occurred through atelectasis or lung fibrosis. Before introducing the epidural catheter we always carried out endotracheal anesthesia with relaxation to achieve perfect conditions for the puncture. This puncture was made between Th 6 and 10, mostly between Th 7/8, the patient lying on one side. An extension of analgesia between Th 3 and Th 12 was intended, which, however, could not be controlled because of simultaneous endotracheal anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

A new tremelloid yeast isolated from Asterophora lycoperdoides (Bull.: Fr.) Ditm.

Reports of a yeast stage of the homobasidiomycete Asterophora lycoperdoides were reexamined. Substantial differences in the physiological description and a gap of 11% G + C content were detected between the yeast and the mycelium. On the basis of nDNA reassociation experiments and restriction enzyme cleavage patterns of mtDNA using two different enzymes it has been concluded that the yeast strains and the mycelia are probably not the same species. The results of earlier reports about the life cycle, however, cannot be explained with these data. This yeast is newly described, because it shows unique physiological properties and no significant homology in DNA-DNA reassociation experiments to species it would normally be identified with in the literature. Because of its dolipore with cup-shaped parenthesome, we prefer the term tremelloid over assigning the strains to any existing genus, because no sexual structure or ballistospore has been observed so far.

Culture Media↗
PubMed1988

Quantitation of neurochemically identified neurons in reaggregate tissue cultures.

The study of cellular interactions during the development of the nervous system is facilitated by the use of the reaggregate tissue culture system. In this system, embryonic neurons are dissociated from one another and allowed to reaggregate in rotatory culture, where they resume their normal differentiation. Reaggregates provide a model for studying neuronal development and cell interactions under conditions which allow for the control of a large number of variables, such as the numbers of cells which are allowed to interact, the presence or absence of appropriate target cells, and the chemical environment in which the neurons develop. For quantitative purposes, it is necessary to estimate the numbers of cells of a given neurochemical or morphologic type. Here we describe a computer-assisted counting system which allows one to determine the numbers of neurochemically identified neurons within reaggregate cultures from the counting of such neurons in a randomly selected sample of thirty 10-micron sections from the reaggregates in a given flask. These sections represent less than 0.5% of the total number of sections derived from the reaggregates in a single flask. In addition, the system allows one to quantitatively compare differences in the numbers of such neurons between experimental flasks utilizing appropriate statistical methods. A comparison of the number of central dopaminergic neurons estimated by this method with the direct counting of such neurons in serial sections of single reaggregates resulted in excellent agreement as to the number of dopaminergic neurons within a given experimental flask.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Stimulation of human and murine adherent cells by bacterial lipoprotein and synthetic lipopeptide analogues.

Lipoprotein from the outer membrane of Escherichia coli and its synthetically prepared N-terminal lipopeptide segments Pam3Cys-Ser-Ser-Asn-Ala and Pam3Cys-Ser, as well as lipoprotein from other Enterobacteriaceae, constitute potent polyclonal B lymphocyte activators. Here, we demonstrate that these compounds were also able to stimulate human and murine leukocytes: in murine macrophages, we could show the induction of interleukin 1 release by the mitogens, as measured in the thymocyte proliferation assay. Moreover, murine peritoneal exudate cells were stimulated to secrete prostaglandins E2 (PGE2) and F2 alpha (PGF2 alpha). The effect of Pam3Cys-Ser on the murine macrophage cell line P388D1 was also tested: the compound induced an increase in proliferation, as measured by a thymidine incorporation assay. In addition, the cell line could be induced to release IL 1 into the supernatant. Correspondingly, induction of IL 1 release could also be demonstrated in human mononuclear cells. Our results demonstrate that the two novel synthetic lipopeptides are potent stimulators for human monocytes and murine macrophages. These findings may be important for the elucidation of the role of these bacterial surface components in the course of bacterial infections.

Animals↗
PubMed1988

Electric muscle stimulation in the hind leg of the spontaneously hypertensive rat induces a long-lasting fall in blood pressure.

The influence of prolonged low-frequency, low-intensity electric stimulation of the gastrocnemius muscle or of the biceps femoris muscle on blood pressure and heart rate was investigated in unanaesthetized, spontaneously hypertensive rats (SHR). In both groups, elevations of blood pressure and heart rate were elicited during the 60 min of muscle stimulation. After cessation of the stimulation, a depressor response developed within 60 min. Thirty to sixty minutes post-stimulation the fall in blood pressure was 19 +/- 3 and 17 +/- 4 mmHg, respectively (mean +/- SE) compared with controls. In both groups, the depressor response lasted for over 5 h. In addition, the gastrocnemius-stimulated animals also developed a post-stimulatory bradycardia. In one group of SHR the sciatic nerve was anaesthetized with bupivacaine. The arousal response during stimulation was similar to that in the other groups, but after termination of stimulation blood pressure returned to the control level without any further drop. To investigate further the neurotransmitters involved, one group of gastrocnemius-stimulated SHR was given naloxone by infusion during the stimulation. A modest post-stimulatory blood pressure fall also occurred in this group, but it lasted only 90 min. Another SHR group was pre-treated with parachlorophenylalanine, a serotonin synthesis blocker, which completely abolished the post-stimulatory depressor response. These results indicate that prolonged muscle stimulation gives rise to a post-stimulatory long-lasting drop in blood pressure and that this response is mediated by somatic nerve afferents. Involvement of the endorphin and serotonin systems is also suggested.

Afferent Pathways↗
PubMed1988

Effects of voluntary physical exercise on cardiac function and energetics in spontaneously hypertensive rats.

The influence of voluntary physical exercise in running wheels on myocardial function, cardiac oxygen utilization and cardiovascular response to emotional stress was analysed in the spontaneously hypertensive rat. After 6 weeks of exercise, a significant increase in resting cardiac output was found, which was due to an elevation of stroke volume. However, voluntary training for 12 weeks had no effect on resting blood pressure or on the blood-pressure response to mental stress. Cardiac function was also examined in vitro. At a low aortic diastolic pressure, it was markedly augmented in trained spontaneously hypertensive rats. At high aortic diastolic pressure, maximal cardiac function was similar in the two groups. Myocardial oxygen consumption (mumol min-1 g-1) for a given level of external work was reduced in trained, compared with non-exercised control spontaneously hypertensive rats. Chronic physical exercise thus greatly improved myocardial function at a subnormal perfusion pressure, suggesting better nutritional supply to the myocardium, probably created by an increased capillary surface area.

Animals↗
PubMed1988

Investigations on the mechanism of a diminished inotropic isoprenaline effect in isolated rat hearts after high linoleic acid diet.

Male Wistar rats were fed on a diet rich (13.3 J%) or poor (0.5 J%) in linoleic acid for 10 weeks. The inotropic and chronotropic effects of isoprenaline (100 ng) in isolated perfused hearts were reduced after a linoleic acid rich diet by 36% and 51%, respectively, with an accompanying reduction in isoprenaline-induced increase in the ventricular cAMP content. Moreover, the stimulation of adenylate cyclase in homogenates of ventricular tissue was diminished after linoleic acid rich diet. We postulate that the diminished adrenergic cardiac response after high vs. low linoleic acid diets could be due to alterations in the adenylate cyclase activity and cAMP formation.

Animals↗
PubMed1988

The intragastric milieu during gastric ulcer treatment with pirenzepine 50 mg b.i.d. or cimetidine 400 mg b.i.d.

In a double-blind randomised four-center trial 43 patients with gastric ulcer (20 men, 23 women; mean age 52.2 years) were treated with either pirenzepine (P) 50 mg b.i.d. (n = 24) or cimetidine (C) 400 mg b.i.d. (n = 19) during six weeks. In ten patients gastric juice was examined before and at the end of the treatment for concentration and type of the microbial flora, and for nitrite concentration. After six weeks 83% of the patients in both groups were either symptom-free or clearly improved. In 15/24 patients on P (62.6%) and in 13/18 on C (72.2%) the ulcer(s) were healed at the time of control endoscopy. In the ten patients investigated, intragastric concentrations of fungi, bacteria, and nitrite were not significantly changed by the treatment. In gastric ulcer, treatment with pirenzepine 50 mg b.i.d. or cimetidine 400 mg b.i.d. during six weeks does not result in significant microbial overgrowth or generation of nitrite.

Adult↗
PubMed1988

[Intravenous combination anesthesia using alfentanil in infants].

Intravenous anesthesia is a method rarely used during infancy. Only neuroleptanalgesia has a number of indications, especially in major surgery and for seriously ill children. There are several advantages of inhalation anesthesia in infancy: good control of anesthesia because of low fat-muscle mass, low functional residual capacity, relatively increased alveolar ventilation, and increased cardiac output. Potential disadvantages of inhalation anesthesia in infancy are numerous: The necessity of high concentrations of inhalational agents may cause myocardial depression and blood pressure drops, the analgetic potency is very low, damage to surfactant is possible, there is a prolonged awakening period in many cases, and cerebral blood flow and intracranial pressure can be increased by inhalation anesthetics. Positive results with the short-acting opiate alfentanil in adult lead us to the idea of replacing routine inhalation anesthesia by a combination of low-dose halothane and intermittent injections of alfentanil. Fifty infants undergoing corrective orthopedic surgery of the hip and lower limb were anesthetized with the combination of alfentanil and halothane described in Fig. 1. Patient data are shown in Table 2. All children were premedicated orally with flunitrazepam 0.1 mg/kg body weight and Bellafolin 1 drop/kg and were primarily anesthetized via inhalation of oxygen/N2O/halothane. After relaxation with vecuronium, intubation and administration of alfentanil, halothane concentrations were reduced to low maintenance doses. Intraoperative und postoperative circulatory parameters showed remarkable stability. Postoperative blood gas analyses--in 8 cases done using capillary blood--gave no hint of any respiratory or metabolic disorder caused by the anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil↗
PubMed1988

Bowel preparation prior to colonoscopy using a limited intake of electrolyte solution for cleansing. A comparison between peroral and rectal intestinal lavage evaluated through degree of cleansing, acceptability by the patient and nursing time involved.

In a randomised single-blind study, peroral intestinal cleansing was compared with rectal lavaging in 55 completed colonscopies. After rapid oral intake of 1.5 l cold (5-7 degrees C) electrolyte solution, a better cleansing of colon was observed than after rectal lavage. A majority of patients preferred this method. More than one hour per patient of the nurses' time was saved in the electrolyte solution group. The amount of electrolyte solution used was less than in previous studies. It did not result in undesirable fluid retention in the colon. No serious side effects were observed, and only minor changes in the patients' weight and plasma osmolality occurred in the electrolyte solution group.

Administration, Oral↗
PubMed1988

[Effect of metabolic changes in the liver on the cytotoxic activity of cyclophosphamide in the incisor of rats].

The incisor of the rat is a sensitive biological indicator which records nutritive and hormonal disorders as well as toxic influences. The present investigation was aimed to provide information whether or not the manifestation of cyclophosphamide-caused hypoplasias could be altered by an induction (phenobarbital) or inhibition (carbon tetrachloride) of the liver biotransformation capacity. Cyclophosphamide (15 or 30 mg/kg) was injected intraperitoneally. Pretreatment of the rat with phenobarbital produced an increase (35%) of the malformation, whereas carbon tetrachloride led to a dose dependent decrease (30 or 50%). Our investigations suggest that the cyclophosphamide induced defect of the incisor is due to an alteration of the metabolic liver function.

Animals↗
PubMed1987

Cardiotoxicity testing of organic solvents by coronary artery ligation in closed-chest rats.

The effect in coronary artery occlusion was investigated in closed-chest anesthetized (urethane, pentobarbital, ether) and conscious rats. The parameters measured were: arrhythmia development, heart rate changes and mortality. Lowest mortality rate and less severe arrhythmias were observed in the urethane group. In urethane-anesthetized rats single oral administration of carbon disulphide (8.3 mmol/kg), chloroform (5.7 mmol/kg), trichloroethylene (16.7 mmol/kg) and ethanol (174 mmol/kg), respectively, 1 h prior to coronary occlusion reduced survival rate accompanied by marked influences on arrhythmia development. The coronary occlusion method in closed-chest rats under urethane-anesthesia appears to be a valuable tool for investigating cardiotoxic effects of chemicals.

Anesthetics↗