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Biomedical subjects

T Frieling

Publications and source records attributed to T Frieling.

At least 91 records · Page 5Linked to original sources
PubMed1991

Synaptic transmission in submucosal ganglia of guinea pig distal colon.

Intracellular electrical recording was used to investigate synaptic behavior of ganglion cells in the neural networks of the submucosal plexus of the guinea pig distal colon. Fast excitatory postsynaptic potentials (EPSPs), mediated by nicotinic receptors, were found in all S/type 1 neurons, 70% of AH/type 2, 75% of type 3, and 95% of type 4 neurons. Slow EPSPs were characterized by membrane depolarization, increased input resistance, enhanced action potential discharge, and suppression of hyperpolarizing afterpotentials in 64% of the S/type 1 neurons, 74% of AH/type 2, 31% of type 3, and 70% of type 4 neurons. Micropressure application of acetylcholine evoked a two-component depolarizing response consisting of an initial transient with decreased input resistance followed by a prolonged depolarization associated with increased input resistance. The transient response was suppressed by nicotinic-blocking drugs. Muscarinic antagonists suppressed the prolonged response. Acetylcholine acted also at presynaptic muscarinic receptors to suppress stimulus-evoked fast EPSPs. No stimulus-evoked inhibitory synaptic potentials were observed. Norepinephrine, applied by microejection, acted at alpha 2-adrenoceptors to hyperpolarize the membrane potential in association with decreased neuronal input resistance.

Acetylcholine↗
PubMed1991

Neural 5-hydroxytryptamine receptors regulate chloride secretion in guinea pig distal colon.

The effects of 5-hydroxytryptamine (5-HT) on epithelial short-circuit current (Isc) were determined and related to the 5-HT effects on electrical and synaptic behavior of neurons in the submucosal plexus of the guinea pig colon. 5-HT evoked a biphasic increase in Isc that was reduced by bumetanide, Cl(-)-free solutions, atropine, and mecamylamine and abolished by tetrodotoxin. The 5-HT response was mimicked by 2-methyl-5-HT, but not by 5-hydroxyindalpine, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, and 5-methoxytryptamine (5-MeOT). ICS 205-930 suppressed the 5-HT response. Electrical field stimulation of submucosal neurons evoked an increase in Isc indicative of Cl- secretion that was reduced by 5-MeOT and enhanced by 2-methyl-5-HT. Application of 5-HT to submucosal neurons by micropressure ejection resulted in membrane depolarization, augmented excitability, and repetitive spike discharge. The depolarization was biphasic, consisting of rapidly and slowly activating components. The rapidly activating component was suppressed by ICS 205-930. Fast excitatory postsynaptic potentials evoked by electrical stimulation of interganglionic connectives were suppressed by 5-HT and 5-MeOT. These results suggest that 5-HT activates 5-HT3 receptors, which mediate fast excitatory responses in submucosal neurons, leading to release of acetylcholine at nicotinic and muscarinic synapses and stimulation of Cl- secretion. Presynaptic inhibition suppresses acetylcholine release and results in attenuation of neurally evoked Cl- secretion.

Animals↗
PubMed1991

Serotonin receptors on submucous neurons in guinea pig colon.

Intracellular microelectrodes were used to investigate the neuropharmacology of 5-hydroxytryptamine (5-HT) in the submucous plexus of the distal colon of the guinea pig. Three effects resulted from application of 5-HT to submucous neurons. Two of the effects were components of a biphasic depolarization mediated by receptors on the neuronal cell body. The third was suppression of acetylcholine release at nicotinic synapses on the cell bodies and was mediated by presynaptic 5-HT receptors. The initial component of the biphasic depolarization was a rapidly activating response characterized by increased ionic conductance and a tendency for rapid desensitization. Pharmacological analysis with selective agonists and antagonists suggested mediation of this response by the 5-HT3 receptor subtype. The second component of the depolarizing response was a slowly activating and long-lasting depolarization associated with decreased ionic conductance. Analysis of this response suggested it was mediated by the 5-HT1P receptor subtype. Identification of the presynaptic receptors for 5-HT was equivocal. These receptors did not behave like 5-HT3 or 5-HT1P receptor subtypes. The putative 5-HT4 agonist 5-methoxytryptamine was equipotent with 5-HT in producing presynaptic inhibition at the fast nicotinic synapses.

Analysis of Variance↗
PubMed1991

Visceral afferent neuropathy in diabetic gastroparesis.

OBJECTIVE: To determine whether a lack of symptoms in diabetic patients with gastrointestinal motility disorders is associated with visceral afferent neuropathy. RESEARCH DESIGN AND METHODS: We investigated cerebral evoked potentials (EPs) after esophageal stimulation in 10 patients with motor dysfunction of the gastrointestinal tract and in 10 healthy control subjects. All patients had insulin-dependent diabetes mellitus (5 men, 5 women, age range 31-60 yr, diabetes duration 8-36 yr, 10 of 10 with polyneuropathy, 6 of 10 with cardiac autonomic neuropathy). Their esophageal and gastric motor disorders had been diagnosed by scintigraphy, and gastrointestinal stenosis had been excluded by gastroscopy. Only 2 patients had severe symptoms, whereas 6 patients complained of minor discomfort (distension, bloating), and 2 patients were symptom free. RESULTS: EPs were recorded after electrical stimulation of the esophagus (32 cm from the incisors) at intensity just above the perception threshold. All control subjects exhibited regular EPs at 0.1 ms/30 mA stimulation intensity. In 6 diabetic patients, no EPs were detected at 0.1 and 0.3 ms/30 mA, and the perception thresholds were significantly elevated. In 4 patients with normal perception threshold, EPs of regular shape but decreased amplitude were recorded. These patients had mild or severe gastroparetic complaints. CONCLUSIONS: These data show for the first time an association between a lack of symptoms in diabetic gastrointestinal motility disorders and visceral afferent neuropathy.

Adult↗
PubMed1990

Cerebral electrical potentials evoked by balloon distention of the human esophagus.

UNLABELLED: Cerebral evoked potentials provide a technique for evaluation of central nervous processing of information derived from a variety of sensory modalities. Evoked potentials associated with balloon distention of the smooth muscle esophagus were studied in 14 adult volunteers. Stimulation was applied via repeated inflation and deflation of a balloon attached to a pressure pump that cycled at 0.2 Hz. Cortical electrical responses were recorded from scalp electrodes at Cz, Cz', and Pz of the international 10-20 System for electroencephalographic recording. The recording electrodes were referenced to Fpz and averaged over a 1-s period for 100 repetitions. Latencies, amplitudes, and waveforms of the evoked potentials were compared with controls consisting of pump on/balloon detached, auditory masking, and conventional somatosensory posterior tibial nerve stimulation. Polyphasic evoked potentials were obtained in all subjects, and maximum positive deflections occurring with latencies of 202-396 ms. Maximal amplitudes ranged from 2.5-8.3 microV. Latencies and amplitudes of the evoked responses were highly reproducible in each subject with considerable variation among subjects. CONCLUSIONS: (a) Reproducible evoked potentials with distinctive waveforms can be recorded in response to esophageal balloon distention in humans; (2) long latency of the evoked potentials suggests involvement of nonmyelinated visceral afferent pathways; (3) the evoked potentials are probably specific to mechanical stimulation rather than being nonspecific arousal responses; and (4) the results support this as a promising new method for investigation of the neurobiology of gastrointestinal sensation in humans that may help clarify pathological conditions of the irritable esophagus syndrome and esophagus-related chest pain.

Adult↗
PubMed1989

Cerebral responses evoked by electrical stimulation of rectosigmoid in normal subjects.

We used electroencephalographic methods to evoke and record cerebral responses to electrical stimulation of the rectosigmoid colon in eight healthy male volunteers, 20-40 years old. The stimulus was applied via a probe equipped with bipolar ring electrodes which were attached by suction to the mucosa. The probe was positioned 20 cm above the anus. Cerebral responses were recorded by EEG electrodes. Evoked potentials (EPs) in response to electrical stimulation consisted of a series of successive peaks and troughs in the EEG with good reproducibility within and between subjects. The shape and latencies of the intestinal EPs were comparable to other types of EPs reported before. It is concluded that reproducible EPs can be recorded from the scalp after electrical stimulation of the rectosigmoid. The similarity in appearance of these EPs to those previously reported suggests that visceral afferents were stimulated. The technique may become a useful tool to study visceral nervous connections to the brain in health and disease.

Adult↗
PubMed1989

Age and sex and anorectal manometry in incontinence.

Although the prevalence of fecal incontinence is greater in women compared with men and in elderly subjects compared with younger subjects, data regarding the influence of age and sex on anorectal performance in continent and incontinent patients are conflicting. The authors, therefore, investigated age- and gender-related changes in anal resting and squeeze pressure as well as in sphincter relaxation after rectal balloon distention in 75 patients with fecal incontinence of different pathogenesis and in 99 continent patients by multichannel anorectal manometry. As a group, incontinent patients usually exhibit lower pressure profiles than do continent patients regardless of age and gender; however, both the resting pressure of the internal anal sphincter and the voluntary contractile pressure of the external anal sphincter are decreased with age, and both are lowered in women compared with men. Sphincter relaxation and perception of gastrointestinal events are not altered in incontinent patients, and they are not different between men and women or between elderly and younger patients.

Adult↗
PubMed1989

Cerebral responses evoked by electrical stimulation of the esophagus in normal subjects.

Cerebral responses to electrical stimulation of the esophagus were investigated in 11 healthy male volunteers, 20-40 yr old. The stimulus was applied via a probe equipped with bipolar ring electrodes. It was positioned in the middle and distal esophagus at 20 and 37 cm from the incisors, respectively, and sucked to the mucosa. Electrical stimuli (0.1-ms duration, different stimulus voltages) were applied at frequencies of 0.1-1.0 Hz or in randomized order. Cerebral responses to electrical stimulation were recorded after 20-40 stimulations and averaged on a time base of 1000 ms. Evoked potentials consisted of successive peaks and troughs in the averaged electroencephalogram with good reproducibility within and between subjects. Amplitudes of evoked potentials showed a significant reduction with electrical stimulation at 37 cm compared with 20 cm, and with stimulation frequencies of 0.5 and 1.0 Hz compared with 0.2 and 0.1 Hz. Evoked potentials from 37 cm showed longer latencies compared with those from 20 cm. Irregular stimulation and stimulation during mental distraction did not alter these responses. It is concluded that reproducible evoked potentials can be recorded from the scalp after electrical stimulation of the esophagus and that these are transferred centrally via vagal afferents. The technique may become a useful tool in the study of visceral nervous connections to the brain in health and disease.

Adult↗
PubMed1989

[Diagnosis of achalasia--comparison of methods for the evaluation of severity].

To determine the value of endoscopy, manometry, and scintigraphy in predicting the severity of achalasia, 25 patients with primary achalasia of the esophagus were posprectively studied; 17 patients could be examined prior and post pneumatic dilatation. According to the symptoms, the severity was graded from I to IV. While endoscopic findings did not well correlate with the symptom score, the lower esophageal sphincter pressure and the resting pressure in the esophageal body were significantly correlated with the severity of the disease (p less than 0.01). The esophageal retention of radioactivity rose parallel to the symptom score (p = 0.07). Both manometric and scintigraphic findings changed significantly after therapy (p less than 0.01). Manometry and scintigraphy of the esophagus can be used to measure treatment related effects in patients with primary achalasia. Endoscopic findings are not related to subjective complaints, but an endoscopic examination should always be performed to exclude malignancies of the esophago-gastric junction.

Adult↗
PubMed1988

[Achalasia as a mask of cardial carcinoma].

Increasing dysphagia and weight loss between 3 and 30 kg developed in eight patients aged 27-70 years (mean age 53 years) within a period of 1.5 to 12 months. In five patients X-ray film showed the typical pattern of achalasia with dilatation of the tubular oesophagus and a smooth taper of the terminal part. Although in all patients the cardia became patent only after the endoscope had been advanced by pushing it forward to overcome stenosis or after bougienage, and although the malignoma had always been included in differential diagnostic considerations, a malignoma was identified only three times in 30 histological examinations. Oesophageal manometry demonstrated findings characteristic of achalasia in five patients, in three patients the examination could be performed only incompletely. In six patients computed tomography revealed pathological hypertrophy of the cardiac wall. Intraoperatively all cardiac tumours were in an advanced stage.

Adult↗
PubMed1988

Family occurrence of achalasia and diffuse spasm of the oesophagus.

In view of the unknown aetiology of achalasia and diffuse oesophageal spasm we report four families (father/son, mother/son, brother/brother, cousin/cousin) with achalasia and oesophageal spasm examined by radiology, endoscopy and manometry. Family occurrence of oesophageal motor disorders supports the hypothesis that a genetic trait may play a role in the pathogenesis. The family coincidence of achalasia and oesophageal spasm supports a close relationship between the two diseases.

Adult↗
PubMed1988

[Reactions of the liver to high caloric enteral feeding with formula diets].

We studied serum hepatic enzyme alterations in 36 patients receiving continuous enteral hyperalimentation. In 50% of the patients studied a marked increase in liver enzymes could be noticed. Elevations returned to normal either spontaneously during enteral feeding or after feeding was discontinued. In 7 patients, alkaline phosphatase decreased significantly 21 +/- 13 days after institution of tube feeding. The rise in liver enzyme values could not be accounted for by preexistent hepatobiliary affection, caloric load or composition of the formula diet. Further studies are needed to determine whether cyclic isocaloric enteral nutrition will minimize complications and hepatic enzyme changes after enteral nutrition.

Adolescent↗
PubMed1988

[Anorectal motility in systemic scleroderma].

We prospectively compared esophageal and rectal motility data from 7 patients with progressive systemic sclerosis (4 females, 3 males) to esophageal recordings in 22 and anorectal recordings in 9 healthy controls. All patients with sclerosis exhibited motility disturbances in the lower esophageal sphincter (LES): LES resting pressure, LES relaxation amplitude and duration, and the number of incomplete LES relaxations were significantly different compared to the controls. All patients had alterations of anorectal motility: resting pressure, maximal squeeze pressure, and sphincter relaxation amplitude following balloon distension of the rectum were significantly decreased as compared to the control subjects. We conclude that esophageal and anorectal manometry are comparable in their sensitivity to differentiate between patients with systemic sclerosis and normal subjects.

Anal Canal↗