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Biomedical subjects

H Petersen

Publications and source records attributed to H Petersen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Transcranial magnetic stimulation in patients with Rett syndrome: preliminary results.

Transcranial magnetic stimulation was used to investigate Rett patients (n = 31, age 2-38 years). The results were compared to healthy control persons (n = 112, age 1 month-35 years). The peripheral conduction time showed no difference between the patients and control persons. The mean central conduction time, however, was shorter in the younger patients with Rett syndrome, and this is particularly evident in the youngest. This phenomenon could be interpreted as cortical and/or spinal hyperexcitability which occurs during the early stages of Rett syndrome.

Adolescent↗
PubMed1996

Relational database for drug-use review of Tennessee Medicaid claims.

The development of a relational database from Tennessee Medicaid files for the purpose of retrospective drug-use review (DUR) and application of the database for DUR of angiotensin-converting-enzyme inhibitors (ACEIs) are described. Computer queries were designed to create profiles of physicians' or pharmacies' experiences from claims data and other Medicaid data. Outlying patients (patients for whom at least one DUR criterion was unmet) were grouped according to their physicians or pharmacies. Thresholds for defining outlying physicians and pharmacies (i.e., those with more than a specified number of outlying patients) were based on the provider population instead of the patient population as a whole; aggregating patient outliers by provider allowed trends of inappropriate practices to be detected. As the threshold for outlying providers rose, the number of such providers fell, as did the number of outlying patients with whom they were associated. Stratification of the outliers by provider for specific drug-drug interactions and drug-disease complications afforded the option to set individual thresholds for outlying providers based on individual subsets; for example, for ACEIs, a threshold of greater than five patient outliers could be set for the criterion of no concurrent potassium supplements and a threshold of greater than three, for the criterion of no unmonitored concurrent lithium therapy. Tennessee patients formerly covered by Medicaid are now enrolled in managed care plans, and the flexibility of the database has allowed it to be modified accordingly. The relational database allows flexibility in the analysis of certain patterns of drug use. Such a database may be useful to other Medicaid programs that are converting to managed care models.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Auditory feedback regulation of perturbed stance in stroke patients.

The effect of auditory input on impaired postural control perturbations was evaluated in two groups of stroke patients participating in a rehabilitation programme after a recent (< 12 months) and single episode of stroke, or less recent (> 12 months), and multiple episodes of stroke. Auditory input took the form of feedback signals generated by the forces actuated by the feet on a force platform in response to the patient's postural movements. Vibratory stimuli applied to the calf muscles induced sudden perturbations which the patients had to counteract to maintain an upright stance. The effect of auditory feedback in facilitating the maintenance of stance was measured in terms of sagittal torque variance (body sway) recorded on a force platform. In the presence of auditory feedback, body torque variance in response to perturbed posture was significantly reduced in the recent stroke group, whereas in the less recent stroke group the auditory feedback did not prove effective. Moreover, learning seems essential to utilize the auditory feedback.

Acoustic Stimulation↗
PubMed1995

Postural control and vestibular function in patients selected for cochlear implantation.

Postural control and vestibular and eye motor function were evaluated in 7 postlingually deaf patients before cochlear implantation as vibration toward the calf muscles or galvanic electrical stimulation of the vestibular nerves perturbed stance. The patients were compared with 21 control subjects. Vibration-induced bodysway was increased in the patients compared to the normals. Galvanic stimulation induced a bodysway that was not significantly different from that of the control group suggesting that the patients selected for cochlear implantation, and with otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. This finding may contribute with a complementary hypothesis to the causes of dizziness among cochlear implant patients.

Adult↗
PubMed1995

Vestibular stimulation perturbs human stance also at higher frequencies.

The effect of primary vestibular disturbance on postural control was investigated in 11 normal subjects exposed to perturbation by bi-polar binaural galvanic stimulation of the vestibular nerve. The stimulus consisted of 30 s of sinusoidal galvanic stimulation at frequencies of 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 3.0 and 4.0 Hz, with a current of +/- 1 mA, the subject standing with open or closed eyes and the response evoked being recorded with a force platform. As compared with resting values, i.e. no stimuli, variance of lateral body sway was significantly greater at all frequencies tested in the closed eyes condition and at frequencies of 0.2, 0.5, 1.0, 3.0 and 4.0 Hz in the open eyes condition; using a high pass filter with a cut-off frequency of 0.1 Hz, variance of lateral body sway was significantly greater at frequencies 0.2, 0.3, 0.5, 1.0 and 2.0 Hz in the closed eyes condition and at frequencies 0.5 and 2.0 Hz in the open eyes condition. These findings suggest that in the lateral plane vestibular input affects and probably contributes to human postural control over a wider frequency range than suggested by findings in previous studies. Moreover, the visual contribution appears to enable the subject to suppress vestibular input causing lateral body sway only in the lower frequency range (here at 0.2 and 0.3 Hz). This evidence of vestibular contribution to postural control in the lateral plane is consistent with the response characteristics of the vestibulo-ocular reflex.

Adolescent↗
PubMed1995

The prevalence of gastro-oesophageal reflux disease.

Estimation of the prevalence of gastro-oesophageal reflux disease (GORD) is difficult because of the lack of an accepted definition and a gold standard. Based on the occurrence of reflux symptoms and on the use of antacids in the population, the prevalence of GORD may be estimated at about 10%. The 1-year incidence of endoscopic oesophagitis has been shown to be 1.2%. In an endoscopic population study, oesophagitis was found in about 10% of the adult population. However, the criteria used for the diagnosis were disputable. The true prevalence of oesophagitis is probably about 5%, higher in males than in females. The severity of GORD tends to increase with age, with regard to both symptoms and oesophagitis.

Adult↗
PubMed1995

The clinical significance of hiatus hernia.

A close association has been found between hiatus hernia (HH) and reflux symptoms, oesophagitis, and other abnormalities known to be related to gastro-oesophageal reflux disease (GORD). However, GORD is not always associated with HH and HH is not always associated with GORD. If a patient suffers from symptoms compatible with GORD, the finding of a HH may be taken to support the diagnosis. In a patient with an established diagnosis of GORD the finding of a HH may emphasize the severity of the disease, particularly so if the HH is large.

Gastroesophageal Reflux↗
PubMed1995

The natural course of peptic ulcer disease and its predictors.

BACKGROUND: Little is known about today's natural course of peptic ulcer disease (PUD). METHODS: A follow-up study based on a structured telephone interview was attempted in 728 patients with an endoscopic diagnosis of peptic ulcer in 1980-84. RESULTS: Seven patients (1%) died because of PUD during the 8- to 10-year follow-up period. Of the 441 interviewed patients 15.2% had experienced no further clinical manifestations of PUD, 10.9% had had bleeding and 0.7% perforation, and 17.5% had been operated on. The operated patients reported fewer symptoms (p < 0.01) during the last 2 weeks before the interview than those not operated on. On an average the unoperated patients had had symptoms and had used histamine-2-receptor antagonists (H2RA) 12 and 10 weeks per year, respectively. Long-term treatment with H2RA was reported by 18%. More than one-third (36%) of the unoperated patients stated that the symptoms had had a significant negative impact on their lives. Age at onset of disease and index ulcer, family history, use of anti-inflammatory drugs and alcohol, bleeding, and another chronic disease were found to be significant predictors of the course. CONCLUSION: In more than one-third of the patients with PUD the course is still burdened with many symptoms and complications.

Adolescent↗
PubMed1995

Postural control and vestibulospinal function in patients selected for cochlear implantation.

Postural control, vestibular and eye motor function were evaluated in seven postlingually deaf patients before cochlear implantation and were compared with 21 control subjects. Vibration to the calf muscles or galvanic electrical stimulation of the vestibular nerves, perturbed stance and body sway velocity, statistical variance of antero-posterior body sway and identification of characteristic parameters of postural dynamics were all evaluated. Vibration-induced body sway was increased among the patients compared with the normal subjects and there were differences in characteristic parameters of postural dynamics, indicating decreased postural control. Galvanic stimulation induced a body sway not significantly different from the control group suggesting that the patients selected for cochlear implantation, and with an otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. Thus, postlingually deaf subjects who perceive a sensation of sound at electrical promontorial stimulation also respond with increased body sway to electrical stimulation aimed at the vestibular nerves. This finding may contribute an additional hypothesis to the causes of dizziness among cochlear implant patients, complementary to the that of wrongly placed electrodes and peroperative vestibular lesions.

Adult↗
PubMed1995

Critical issues in the management of gastroesophageal reflux disease.

AIM: To discuss some of the critical issues in the management of gastroesophageal reflux disease (GERD). OPINION: GERD is a chronic relapsing disease characterized by pathological exposure of the distal esophagus to gastric acid. Diagnosis of the condition can often be made on the basis of symptomatology alone. Endoscopy can help in assessing the degree of esophageal damage, influencing the choice of therapy, and should be performed at least once during a symptomatic patient's lifetime to exclude a diagnosis of Barrett's esophagus. However, endoscopy is mandatory at diagnosis if alarm symptoms are present. Treatment should aim to provide the lowest degree of acid suppression needed for the control of symptoms. Proton pump inhibitors (PPIs) represent the most cost-effective treatment option for the short- and long-term management of GERD. Compared with standard- and high-dose H2-receptor antagonists, PPIs result in superior and faster healing and symptom relief across all grades of esophagitis and are more effective at maintaining patients in symptomatic and endoscopic remission. Treatment with PPIs has also been shown to reduce the rate of recurrent stricture after initial dilatation. PPIs are generally well tolerated, and to date there have been no reports of gastric dysplasia resulting from their long-term use. Anti-reflux surgery should be reserved for patients who are unresponsive to continuous PPI therapy or perhaps for young patients. It will be several years before the impact of laparoscopic fundoplication as a cost-beneficial therapy for GERD can be assessed. CONCLUSION: The superior clinical efficacy of PPIs when compared with any other drug regimen for GERD make them the treatment of choice for the short- and long-term management of this troublesome condition.

Anti-Ulcer Agents↗
PubMed1995

Acoustic cues and postural control.

The effect of auditory input on postural control was evaluated in separate experiments performed in three groups of healthy volunteers. Auditory input took the form either of feedback signals generated by a force platform in response to the subject's postural control movements, or of field orientation (frame of reference) input provided by repeated clicks emitted by loudspeakers in a normally reverberative environment. The effect of these acoustic cues was measured in terms of body sway recorded on a force platform during stance perturbations induced by vibratory stimuli applied to the calf muscles either at low (120mW) or high (850 mW) intensity, the subject standing with eyes closed or open, as instructed. In the presence of feedback auditory input, body sway in response to low intensity vibratory stimulation was significantly reduced, but not that in response to high intensity stimulation. This may be due to the fact that the head and body movements induced by high intensity vibratory stimulation are so rapid and powerful that they override the information available or to the subject using other strategies for postural control in which auditory feedback, at least in the form used here, does not contribute useful information. The availability of field orientation input did not reduce body sway in response to vibratory stimulation at low intensity. This was probably due to the cognitive lag which precluded use being made of the input before the fast proprioceptive responses to vibratory stimulation had already occurred.

Acoustic Stimulation↗
PubMed1994

Antibodies of symptomatic human immunodeficiency virus type 1-infected individuals are directed to the V3 domain of noninfectious and not of infectious virions present in autologous serum.

The present study was designed to determine the antibody specificity for the human immunodeficiency virus type 1 (HIV-1) V3 domains of infectious and noninfectious virions present in the serum of AIDS patients. To accomplish this, HIV-1 was isolated in the presence of autologous antibodies from the serum samples of six AIDS patients in HIV-1-negative donor peripheral blood mononuclear cells by short-term cultivation. The isolated virus, defined as the infectious cell-free virus (iCFV), was characterized by sequence analysis of the proviral DNA coding for the third hypervariable (V3) region of the external glycoprotein gp120. This was carried out by amplifying and cloning the V3 region. In all six cases studied, 20 randomly selected V3 clones derived from the proviral DNA of the iCFV, 20 clones from patient cell-free virus, and 20 clones from cell-integrated virus were sequenced to study the distribution and frequency of the intrapatient virus population. The number of major virus variants in the six patients ranged from three to nine. The various V3 sequences found in the AIDS patients showed the typical amino acid pattern of the syncytium-inducing and non-syncytium-inducing viral phenotypes characteristic for the late stage of infection. However, only one patient-specific iCFV variant was detected within the 20 V3 clones analyzed per virus isolation. For the six patients a total of 34 V3-loop variants, either iCFV or non-iCFV, was observed. All 34 V3-loop sequences were expressed as glutathione-S-transferase fusion proteins (V3-GST). The autologous antibody response to the V3-GST fusion proteins was studied by Western immunoblot analysis. A strong antibody response to almost all non-iCFV V3-GST proteins was found in the sera of the six patients. In contrast, the autologous antibody response to the six iCFV V3 loops was undetectable (in four patients) or very faint (in two patients) compared with that to the non-iCFV V3 loops. Five of the six iCFV loops showed positively charged amino acids at positions strongly associated with the syncytium-inducing phenotype. These findings suggest that our in vitro isolation system selects for virions which are not recognized by V3-specific antibodies and are infectious both in vitro and in vivo.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Vestibular disturbance at frequencies above 1 Hz affects human postural control.

The effect of primary vestibular disturbance on postural control was investigated in 11 normal subjects exposed to perturbation by bi-polar binaural galvanic stimulation of the vestibular nerve. The stimulus consisted of 30 s of sinusoidal galvanic stimulation at a frequencies of 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 3.0 and 4.0 Hz, with a current of +/- 1 mA, the subject standing with open or closed eyes, the response evoked being recorded with a force platform. As compared with resting values, i.e. no stimuli, variance of lateral body sway was significantly greater at all frequencies tested in the closed eyes condition and at frequencies of 0.2, 0.5, 1.0, 3.0 and 4.0 Hz in the open eyes condition; using a high pass filter with a cut-off frequency of 0.1 Hz, variance of lateral body sway was significantly greater at frequencies 0.2, 0.3, 0.5, 1.0 and 2.0 Hz in the closed eyes condition and at frequencies 0.5 and 2.0 Hz in the open eyes condition. These findings suggest that in the lateral plane vestibular input affects and probably contributes to human postural control over a wider frequency range than suggested by findings in previous studies. The trends in sagittal body sway were similar. Moreover, the visual contribution appears to enable the subject to suppress vestibular input causing lateral body sway only in the lower frequency range (here at 0.2 and 0.3 Hz), but with regard to the concomitant sagittal body sway at a much wider range of frequencies (here at all frequencies tested except 1.5 Hz).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Glucagon-like peptide-1 7-36 amide and peptide YY from the L-cell of the ileal mucosa are potent inhibitors of vagally induced gastric acid secretion in man.

BACKGROUND: Glucagon-like peptide (GLP-1) 7-36 amide and peptide YY (PYY) from the L-cell of the ileal mucosa are potent inhibitors of gastric acid secretion in man. It is not clear, however, by which mechanism(s) they inhibit acid secretion. In dogs the inhibitory effect of PYY on acid secretion may be mediated mainly through neural pathways. The mechanism of action of GLP-1 might be similar. The aim of the present study was to examine the effects of GLP-1 might be similar. The aim of the present study was to examine the effects of GLP-1 and PYY on the vagally induced gastric acid secretion in man. METHODS: A modified sham feeding technique, chew and spit, was used. Six healthy volunteers were randomly assigned to receive intravenous infusion of saline, GLP-1 (41 pmol/kg/h), or peptide YY (50 pmol/kg/h). RESULTS: The infusion of GLP-1 and PYY resulted in plasma concentrations of 60 +/- 9 pmol/l and 84 +/- 11 pmol/l, respectively. GLP-1 and PYY both significantly inhibited the intergrated acid output by 67 +/- 6% and 68 +/- 9%, respectively, compared with the integrated outputs in a control experiment with saline infusion. Serum gastrin and plasma somatostatin concentrations remained unchanged during saline, GLP-1, and PYY infusions. CONCLUSIONS: GLP-1 and PYY are both potent inhibitors of the cephalic phase of acid secretion, indicating that at least part of the inhibitory effect of GLP-1 and PYY in man is mediated through neural pathways. Furthermore, the inhibitory effect seems to be independent of circulating concentrations of gastrin and somatostatin.

Adult↗
PubMed1993

[Consequences of reduced working hours for continuing education of physicians].

Since 1960 the working hours for hospital doctors in training have been reduced by 12.5 hours per week. A questionnaire was sent to all departments in Norway involved in the education of specialists, asking them about the consequences of this reduction. The survey showed that the working time actually paid for today is not so short (42-46 hours per week). It showed indirectly, however, that the time available for education must have been reduced. About 50% stated that the reduction in working hours has had a negative effect on the extent and quality of the education. Nearly all confirmed a conflict of priorities between clinical routines and education. There were seldom opportunities to read medical literature or do research during working hours. There has been no reduction in routine work nor any increase in staff, in spite of a considerable increase in duties connected with the education of specialists.

Education, Medical, Continuing↗