Search PubMed⌕ Search

Biomedical subjects

A Foerster

Publications and source records attributed to A Foerster.

At least 19 recordsLinked to original sources
PubMed1999

Intraspinal and behavioral consequences of nerve growth factor-induced nociceptive sprouting and nerve growth factor-induced hyperalgesia compared in adult rats.

Intraspinal and behavioral events were studied in adult rats with nociceptive nerves that were undergoing collateral sprouting into adjacent denervated skin. This sprouting, which is driven by endogenous nerve growth factor (NGF), did not cause hyperalgesia. For comparison, we studied an exogenous NGF administration that induced hyperalgesia but was too brief to evoke sprouting. When nociceptive nerves sprouted in skin, back-labeling with wheat germ agglutinin-conjugated horseradish peroxidase revealed that their projections sprouted in the cord. The sprouted peripheral nerves now activated more c-Fos-containing interneurons, which stimulus-response studies showed was not due to an increased afferent discharge. We attribute the interneuron recruitment to synaptogenesis following the intraspinal sprouting. Nociceptive stimulation of dorsal skin reflexly activates underlying cutaneous trunci muscle (CTM). When a nociceptive field expanded by nerve sprouting, so did the area of the evoked CTM reflex: this implies a recruitment of CTM motoneurons. We interpret this "matching" of response to stimulus as an adaptive phenomenon ensured by an adaptive intraspinal sprouting of the nociceptive projections. Neither the intraspinal changes nor the reflex changes occurred if peripheral sprouting was blocked by systemic anti-NGF treatment, indicating that the role of endogenous NGF was only in that sprouting. No comparable adaptive events occurred during NGF-induced hyperalgesia. Neither nociceptive fields nor CTM reflexes were affected; however there was a recruitment of c-Fos-expressing interneurons. This recruitment was not explained by peripheral sensitization, and, because sprouting was not involved here, we attribute the recruitment to "synaptic unmasking," i.e., an increased effectiveness of the preexisting excitatory circuitry.

Adaptation, Physiological↗
PubMed1999

Temperature-controlled radiofrequency catheter ablation with a 10-mm tip electrode creates larger lesions without charring in the porcine heart.

BACKGROUND: Radiofrequency catheter ablation of atrial flutter, atrial fibrillation or ventricular tachycardia may be favoured by large lesions. We compared lesions created in unipolar mode using 10-mm/8 F electrodes with those of 4-mm/7 F catheters. METHODS: Ablations were first performed in porcine hearts in vitro (70 degrees C, 60 s, tangential catheter tip-tissue orientation). Anaesthetized pigs were thereafter ablated with 10- or 4-mm catheters in the right atrial free wall (RAFW), inferior vena cava-tricuspid valve (IVC-TV) isthmus and left ventricle (LV). RESULTS: In vitro, lesion length doubled and lesion volume tripled using the 10-mm catheter. Average power supply was 69 (SD12) (10-mm tip) versus 26 (SD7) W (4-mm tip). In vivo, lesion length increased by 50% and lesion volume fivefold. Charring at the lesion surface or sudden impedance rises were not observed in vivo. Histologically, coagulation necrosis and minor haemorrhages were found. One RAFW lesion (10-mm) showed a dissection approaching the epicardium. Fibrinous platelet clots or overt thromboses covered the endocardial surface in half of all lesions. Three 10-mm electrode isthmus lesions extended to the right descending posterior artery and one LV lesion to the left anterior descending artery, but there was no damage to the arterial walls. Following six ablations with the 10-mm electrode and two with the 4-mm tip, injury to the adjacent lung tissue of 0.5 to 6.0 mm depth was found (p = 0.22). CONCLUSION: RF ablation using 10-mm/8 F electrodes created significantly larger lesions. 10-mm electrodes appeared safe in the porcine IVC-TV isthmus and LV, but not in the RAFW.

Animals↗
PubMed1998

Immunoglobulin prolongs survival of pig kidneys perfused ex vivo with human blood.

Intravenous immunoglobulin (IVIG) (Octagam), was used to determine the effect on hyperacute rejection in an ex vivo xenograft model. Six pig kidneys were perfused with IVIG and fresh human AB blood, and six control pig kidneys were simultaneously perfused with albumin and blood from the same donation. The survival of the IVIG-perfused xenografts (median, 6.5 h) was significantly (P = 0.03) longer than the albumin-perfused xenografts (median, 3.5 h). Complement was activated in both groups. The administration of IVIG to the perfused blood resulted in immediate and significantly higher complement activation in the fluid phase as compared with the albumin group. At rejection the fluid phase complement activation was higher in the IVIG group than in the albumin group for C1rs/C1inh complexes, C4bc, Bb and TCC. At the time of rejection both the albumin and the IVIG group demonstrated interstitial tubular haemorrhage, vasculitis or necrosis of glomerular capillaries and glomerular microthrombi. IgM, C1q, C3c, C4 and fibrin were located in arteries and glomeruli and IgG in the interstitium in both groups at rejection. The fluid phase findings are consistent with a modulatory effect of IVIG on complement activation by deviating the classical pathway activation towards the fluid phase. The prolonged survival of the IVIG-perfused kidneys suggests that IVIG may be useful to dampen hyperacute rejection.

Animals↗
PubMed1998

Bipolar radiofrequency catheter ablation creates confluent lesions at larger interelectrode spacing than does unipolar ablation from two electrodes in the porcine heart.

AIMS: Radiofrequency catheter ablation of atrial flutter and fibrillation may be favoured by large, elongated lesions. We compared bipolar ablation with unipolar ablation from one or two electrodes in the porcine heart. METHODS AND RESULTS: In vitro, confluent lesions were reliably created by a 'dielectrode' catheter (energy delivered simultaneously (in parallel) from two 4 mm electrodes spaced 1 mm apart, towards an indifferent electrode), and a 'bipolar' catheter (energy delivered (in series) between two 4 mm electrodes spaced 5 mm apart). Sixteen anaesthetized pigs were randomized to standard unipolar (4), dielectrode (6) or bipolar (6) ablation. Two radiofrequency current deliveries of 30 s duration (70 degrees C) were administered to the inferior vena cava-tricuspid valve isthmus and two to the right atrial free wall in all animals. After 4 h, the lesions were examined macroscopically and histologically. Mean (SD) endocardial lesion length x width x depth measured 7.4 (2.4) x 5.4 (2.2) x 2.8 (0.8) mm in the standard unipolar mode, 10.2 (1.4) x 6.3 (0.7) x 3.3 (1.1) mm in the dielectrode mode and 14.0 (3.6) x 6.0 (1.7) x 3.8 (1.2) mm in the bipolar mode. Thus lesion length increased significantly through the three groups (P < 0.001), while width and depth did not. CONCLUSION: Both dielectrode and bipolar ablation were feasible in porcine right atrial ablation, and created longer lesions than the standard unipolar mode. By allowing a larger interelectrode distance, bipolar ablation created the longest lesions and may be favourable when linear lesions are necessary.

Animals↗
PubMed1998

Radiofrequency current ablation of porcine right atrium: increased lesion size with bipolar two catheter technique compared to unipolar application in vitro and in vivo.

Interruption of atrial flutter and fibrillation by RF catheter ablation may be favored by large, elongated lesions. We administered RF current in unipolar and bipolar mode in porcine right atrium. Bipolar ablation was performed between the tip electrodes of two serially coupled catheters. With 4-mm tip electrodes in vitro, lesion length increased from a mean (SD) of 7.9 (1.2) mm at 3 mm-interelectrode distance (i.e.d.) to 13.3 (3.3) mm at 9-mm IED, but decreased at 12-mm IED due to nonconfluent lesions (P < 0.0001). With 4 mm distal electrodes and 8 mm IED, bipolar lesions were 65% longer than corresponding unipolar ablations. Switching to bipolar mode increased the lesion length more than increasing electrode tip length to 6 mm in unipolar mode. Power and temperature controlled ablation created equally sized lesions. Twelve anesthetized pigs were randomized to unipolar or two catheter bipolar temperature controlled ablation of the right atrial free wall. Bipolar ablation created confluent lesions with endocardial length x width of 13.5 (5.8) x 7.3 (3.7) mm, unipolar ablation 6.4 (2.8) x 4.6 (1.4) mm (P < 0.001 when comparing length and P = 0.013 for lesion width). The atrial lesions in both groups were transmural and extended into hilar lung lesions with maximal depth of 3.0 (1.1) and 2.6 (1.0) mm, respectively (P = 0.44). Five bipolarly and four unipolarly ablated pigs developed right diaphragmal paresis. We conclude that bipolar ablation may be preferable in situations where large, elongated lesions are favorable. The two catheter technique is feasible in porcine right atrium. Both bipolar and unipolar ablation of the porcine right atrial free wall may frequently be complicated by injury to the phrenic nerve and adjacent lung tissue.

Animals↗
PubMed1997

Safety of rapid-rate transcranial magnetic stimulation: heart rate and blood pressure changes.

We examined the influence of rapid-rate transcranial magnetic stimulation on heart rate and blood pressure in 13 healthy volunteers. In a first series three different cortical magnetic stimuli were applied: over C3, C4 and Fz (10/20 system), in a second series additionally over Pz. We also used a stimulus over the brachial plexus and a sham stimulus. Five stimuli of each location were applied with a Cadwell high speed magnetic stimulator using a focal point circular coil. Stimulus train duration was 500 ms, stimulus frequency 20 Hz. Stimulus strength was 70-90% of maximum stimulator output, 20% of maximum stimulator output above subjects' individual motor threshold. The subjects assessed stimulus inconvenience immediately after stimulation. ECG and blood pressure (Finapres) were recorded continuously during the 1 h test. In all subjects there was a clearly marked autonomic response with heart rate acceleration and decrease in blood pressure after all stimuli. There was no difference in responses between cortical stimuli. Blood pressure decrease after sham stimulation was significantly smaller than after cortical stimulation, it was more marked after brachial plexus stimulation. Autonomic reaction correlates well with subjective estimation of stimulus inconvenience. We conclude the observed effect of rapid-rate transcranial magnetic stimulation to be associated to rather an unspecific arousal reaction than to a direct stimulation of autonomic cortex areas. We did not observe any clinically relevant side-effects.

Adult↗
PubMed1997

Development of a biodegradable ureteric stent: surface modification and in vitro assessment.

The aim of the present study was to develop a short bioresorbable ureteric stent and to characterize the chosen polymers with respect to surface modification, biocompatibility, and loading of a biologically active compound. As materials for the stent, poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) were chosen. Degradation experiments were carried out and analytical data were obtained by contact angle measurement, X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy in the attenuated reflection mode (FTIR-ATR). Gas loading technology was used to incorporate biologically active compounds, and biocompatibility of the polymers was assessed by in vitro cellular assays, applying measures such as cell morphology, proliferative activity, and membrane integrity. Our results indicate that surface modification of bioresorbable polymers is a suitable and efficient approach to improve the surface properties. Incorporation of biologically active compounds was possible without loss of activity, and in vitro assessment of cellular responses demonstrated the biocompatibility of the chosen polymers and modifications.

Absorption↗
PubMed1997

Premorbid social functioning in schizophrenia and bipolar disorder: similarities and differences.

OBJECTIVE: This research examined social functioning in childhood and adolescence among patients with schizophrenia and patients with bipolar disorder compared with healthy subjects and investigated the relation between premorbid adjustment and risk factors for psychosis. METHOD: Maternal recall was used to assess the premorbid adjustment of patients with schizophrenia (N = 70) and patients with bipolar disorder (N = 28) recruited from a survey of consecutive hospital admissions for psychosis and of healthy comparison subjects (N = 100) drawn from the same catchment area. RESULTS: The patients with schizophrenia had significantly poorer premorbid adjustment in childhood and adolescence than the comparison subjects and were impaired in both sociability and school adjustment. The patients with bipolar disorder exhibited poorer social impairment in adolescence than the comparison subjects, though to a lesser degree than the schizophrenic subjects, but functioned well at school. There were significant linear trends in the risk of psychosis with worsening premorbid functioning, which was most marked in the schizophrenic group, and a specific linear relation between low birth weight and poor premorbid adjustment among the schizophrenic patients. CONCLUSIONS: Impaired premorbid social functioning is not specific to schizophrenia and is seen also in bipolar disorder. The data support the view that poor premorbid social adjustment is one manifestation of vulnerability to adult psychotic disorders. These results are consistent with other findings pointing to early developmental deficits in patients who subsequently develop psychosis.

Adolescent↗
PubMed1996

HLA-DR matching reduces rejection rate in heart transplantation.

We have studied the influence of serological matching for ten HLA-DR antigens on the occurrence of acute cellular rejection in heart transplantation by correlating the findings in routine endomyocardial biopsies taken during the first posttransplant year with the results of HLA typing of all recipients of a first cardiac graft and their donors during 1983-1994 at our center. We found that recipients of HLA-DR matched hearts had a lower frequency of acute cellular rejection, especially so for the moderate/severe rejection grades. Also, rejection appeared earlier in the DR-mismatched combinations. Whether the mismatch was for one or two DR antigens did not make a significant difference, neither could we demonstrate any influence of HLA-A or -B mismatches. The survival of DR-matched cardiac grafts tended to be higher at 1 year than DR-mismatched grafts, but the difference did not reach statistical significance.

Adolescent↗
PubMed1996

When to suspect and how to diagnose pulmonary lymphangioleiomyomatosis.

The objective of this study was to present clinical and radiological data of eight women with histologically proven lymphangioleiomyomatosis (LAM) diagnosed between 1984 and 1994, and to suggest a diagnostic strategy when LAM is suspected. A review of case reports, including results of biopsies, lung function and radiological procedures was undertaken. The mean age of the women at start of symptoms was 36 years, and the mean age at time of diagnosis 42 years. The most frequent presenting complaint was dyspnea, either in conjunction with pneumothorax (3), chylothorax (2) or on exertion (2). All patients had airflow limitation and markedly reduced gas transfer. Five patients had 16 episodes of pneumothorax. In seven patients multiple cysts were observed on the surface of the lung during thoracotomy while computerized tomography (CT) scans revealed numerous cysts evenly distributed throughout the lung parenchyma. The procedures that confirmed the diagnosis included transbronchial lung biopsy (4), open lung biopsy (2), thoracoscopy (1), thoracotomy (3) and autopsy (1). Three specimens had to be revised before the histological diagnosis was confirmed. It was concluded that the important clues to a diagnosis of LAM are recurrent episodes of pneumothoraces in fertile women, progressive air-flow limitation, markedly reduced gas transfer and characteristic findings on thoracic CT scans. A specific request to the pathologist to stain lung tissue specimens for smooth muscle cells is mandatory.

Adult↗
PubMed1996

Cardiac findings in generalized lipodystrophy.

The cardiac findings in eight patients, two of whom were female, with total lipodystrophy (Berardinelli-Seip's disease) are reported. One of them had the acquired form of the disease. Four patients died at a mean age of 32 years. As far as we know, at least three of them most likely died for cardiac reasons, one shortly after recovering from an attempted suicide. All eight patients had hypertrophic hearts, mostly with deranged diastolic, but also systolic, function. One had pulmonary hypertension. We conclude that generalized lipodystrophy is a serious disease with cardiac affection leading to cardiac dysfunction and early death. There is no specific cardiac treatment, and the treatment should be according to the general guidelines for patients with hypertrophic, dysfunctioning hearts.

Adult↗
PubMed1996

Polypectomy of adenomas in the prevention of colorectal cancer: 10 years' follow-up of the Telemark Polyp Study I. A prospective, controlled population study.

BACKGROUND: The efficacy of polypectomy in preventing colorectal cancer (CRC) has never been demonstrated in a controlled, prospective study. This must be done by randomization within a population with a high prevalence of colorectal polyps, and the feasibility and safety of endoscopic screening examination is a prerequisite for this type of study. METHODS: The present study is a randomized, controlled study of the feasibility and safety of flexible sigmoidoscopic screening of a normal population sample of 799 men and women aged 50-59 years, findings at 2 and 6 years' colonoscopic follow-up, and the appearance of clinical colorectal cancer (CRC) after 10 years. RESULTS: The attendance rate was high, and there were no complications. After 10 years 1 of 400 in the screening group had developed CRC (in the group of 76 (19%) not attending for screening examination). Four of 399 controls developed CRC. CONCLUSIONS: Poor yield of polyps at follow-up, slow growth of in situ polyps, and no clinical CRC among screenees after 10 years provides support to infrequent or no colonoscopic follow-up after initial polypectomy in individuals with otherwise average risk of CRC.

Adenomatous Polyposis Coli↗
PubMed1995

[An answer to an inquiry on diffuse panbronchiolitis. Now it has found its way here!].

Diffuse panbronchiolitis (DPB) is a disease characterised by chronic inflammation in the region of respiratory bronchioles. The condition has mainly been observed in Japanese patients, though isolated cases have been reported from other countries. In a review published in Läkartidningen (37/94), the question was raised of why this disease had not been seen in Scandinavia, and whether this might be the result of missed diagnosis. The diagnostic criteria were listed, and the question was posed of whether (Scandinavian) physicians existed who had encountered patients with chronic sinusitis, persistent cough and inexplicable nodular changes in lung x-rays. As a direct result of this enquiry, the present article reports what may well be the first Scandinavian patient to fulfil all the diagnostic criteria of DPB. The patient responded with improved lung function and normalised blood gases to a combined treatment regimen comprising immunosuppression (cyclophosphamide and prednisolone) and nebulised antibiotics (gentamicin).

Adult↗