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Biomedical subjects

H Johansson

Publications and source records attributed to H Johansson.

At least 91 records · Page 5Linked to original sources
PubMed1998

The information transmitted by ensembles of primary spindle afferents is diminished when ketamine is used as a pre-anaesthetic.

The effect of pre-anaesthetic ketamine on ensemble coding of different stimuli consisting of muscle stretches of various amplitudes was studied for ensembles of simultaneously recorded primary muscle spindle afferents (MSAs). The experiments were conducted on 8 alpha-chloralose anaesthetised cats. Three of the cats received a pre-anaesthetic dose of ketamine (25 mg/kg) injected subcutaneously (ketamine group), while the remaining five animals did not (non-ketamine group). Data for ensemble coding were collected both before and after cutting the ventral root. A method based on principal component analysis and algorithms was used to quantify stimulus discrimination and an ANOVA tested differences between groups as well as differences due to ventral root cutting. When the fusimotor supply was intact, a general trend of an increase in the ability to discriminate stimuli with increasing ensemble size was observed for both groups, however, this trend was significantly greater for the non-ketamine group as compared to the ketamine group. When the ventral root was cut, the discrimination pattern for the non-ketamine group decreased significantly (as compared to before ventral root cutting), however, no change occurred for the ketamine group. Consequently, no difference in discrimination pattern was detected between groups after ventral root cutting. The reduction in information transmitted by ensembles of primary MSAs when ketamine is used as a pre-anaesthetic may suggest that ketamine elicits an adverse affect on the fusimotor system.

Afferent Pathways↗
PubMed1998

Bradykinin and muscle stretch alter contralateral cat neck muscle spindle output.

The objective of this study was to investigate the activity of primary and secondary muscle spindle afferents (MSAs) in neck muscles, when the contralateral splenius or trapezius muscles were (1) exposed to i.m. injection of bradykinin (BK) (6-86 microg/ml), (2) stretched, (3) stretched during exposure to BK or (4) stretched after exposure to BK. It was found that injection of BK, muscle stretch and the combination of the two stimuli significantly excited primary and secondary MSAs via reflex effects onto static fusimotor neurones. BK, alone, and in combination with muscle stretch, induced more frequent, potent and long lasting effects as compared to muscle stretch. The effects of muscle stretch was significantly increased after exposure of BK, indicating that stretch-sensitive nerve-endings within neck muscles are sensitised by BK. The results are discussed in relation to the disturbances in motor co-ordination and proprioception found in patients suffering from chronic muscle pain in the cervical region.

Animals↗
PubMed1998

Alterations in information transmission in ensembles of primary muscle spindle afferents after muscle fatigue in heteronymous muscle.

This study showed that fatigue of the ipsilateral medial gastrocnemius muscle caused a clear-cut reduction in the ability of ensembles of primary muscle spindle afferents from the lateral gastrocnemius muscle to discriminate between muscle stretches of varying amplitude. The results were probably caused by reflex-mediated effects from chemosensitive group III and IV afferents onto the gamma-motoneurons projecting to lateral gastrocnemius muscle spindles. The experiments were conducted on seven cats anaesthetized with alpha-chloralose and a total of 41 primary muscle spindle afferents from the lateral gastrocnemius were registered. Afferents were simultaneously recorded in ensembles of three to 10 afferents. A method based on principal component analysis and algorithms for quantification of stimulus discrimination in ensembles of muscle afferents was used prior to, immediately following and five or more minutes after muscle fatigue had been induced to the ipsilateral medial gastrocnemius muscle. It is well established that the primary muscle spindle afferents play an important role in proprioception and kinaesthesia. Therefore the decrease in the accuracy of the information transmitted by ensembles of primary muscle spindle afferents caused by fatigue in an ipsilateral muscle implies concomitant effects on proprioception and kinaesthesia.

Animals↗
PubMed1998

Central nervous system metastases of cutaneous malignant melanoma--a population-based study.

The objectives of this population-based study were to assess putative prognostic factors for central nervous system (CNS) metastases among patients with cutaneous malignant melanoma, to assess the cumulative risk of CNS metastases in different subsets of patients with recurrent disease, and to describe patient outcome. At a median follow-up of 11 years, 201/2516 patients with melanoma had developed CNS metastases, corresponding to a cumulative risk at 5 years of 7%. In 41 of these 201 patients the CNS metastases were recorded as the first site of recurrence. In a Cox's multivariate model, primary tumor thickness and ulceration in stage I patients were independent risk factors. The cumulative rates of incidence of CNS metastases 5 years after local or regional recurrence as first event were 5 and 42%, respectively. These results may help to form an individually based risk assessment, which might be of value for melanoma patients in certain occupations.

Adult↗
PubMed1998

Neuroendocrine differentiation and nerves in human adrenal cortex and cortical lesions.

Neuroendocrine differentiation and nerve distribution were studied in sections from human cortex (n=11) and cortical lesions (hyperplasias, n=9; adenomas, n=13; carcinomas, n=14) with four markers, namely chromogranin A(CgA), synaptophysin (SYN), neuron-specific enolase (NSE), protein gene product (PGP) 9.5 and small synaptic vesicle protein (SV)2. All but two cases expressed neuroendocrine differentiation. NSE was the most commonly occurring marker and the NSE immunoreactive cells were detected in normal cortex, mainly in zona glomerulosa, as well as in adenomas and carcinomas. SYN and PGP 9.5 immunoreactive cells were especially prominent in the carcinomas, while SV2 immunoreactive cells were seen mainly in normal cortex. The difference in distribution pattern of the neuroendocrine markers between adenomas and carcinomas was not so distinct that it can be used for histopathological diagnosis. The significance of neuroendocrine differentiation in cortex and cortical lesions is uncertain, but may reflect an involvement in special hormonal functions. No obvious relationship was found between the clinical syndromes and the degree of neuroendocrine differentiation. Three of the neuroendocrine markers also visualized nerve structures. PGP 9.5, which is regarded as the most 'general' nerve marker, visualized more nerve structures than did the other markers. Normal cortex contained most immunoreactive nerves, whereas they were less numerous in hyperplasias and sparse or even absent in the neoplasms. The nerves appeared among the parenchymal cells but were particularly prominent around vessels. The results suggest that the cortical nerves influence not only the regulation of the blood supply but also the hormonal regulation at the cellular level.

Adenoma↗
PubMed1998

Occupational exposures and squamous cell carcinoma of the oral cavity, pharynx, larynx, and oesophagus: a case-control study in Sweden.

OBJECTIVES: This community based case-referent study was initiated to investigate aetiological factors for squamous cell carcinoma of the upper gastrointestinal tract. METHODS: The study was based on all Swedish men aged 40-79 living in two regions of Sweden during 1988-90. Within that base, efforts were made to identify all incident cases of squamous cell carcinoma of the oral cavity, oropharynx and hypopharynx, larynx, and oesophagus. Referents were selected as a stratified (age, region) random sample of the base. The response was 90% among cases and 85% among referents. There were 545 cases and 641 referents in the final study group. The study subjects were interviewed about several lifestyle factors and a life history of occupations and work tasks. The exposure to 17 specific agents were coded by an occupational hygienist. The relative risk (RR) of cancer was calculated by logistic regression, standardising for age, geographical region, and alcohol and tobacco consumption. RESULTS: Exposure to asbestos was associated with an increased risk of laryngeal cancer, and a dose-response relation was present. The RR was 1.8 (95% confidence interval (95% CI) 1.1 to 3.0) in the highest exposure group. More than eight years of exposure to welding fumes was associated with an increased risk of pharyngeal cancer (RR 2.3 (1.1 to 4.7)), and laryngeal cancer (RR 2.0 (1.0 to 3.7)). There were indications of a dose-response for duration of exposure. Associations were also found for high exposure to polycyclic aromatic hydrocarbons (PAHs) and oesophageal cancer, RR 1.9 (1.1 to 3.2). Exposure to wood dust was associated with a decreased risk of cancer at the studied sites. CONCLUSIONS: Some of the present findings confirm known or suspected associations--such as asbestos and laryngeal cancer. The study indicates that welding may cause an increased risk of pharyngeal as well as laryngeal cancer. The findings corroborate an association between exposure to PAHs and oesophageal cancer.

Adult↗
PubMed1998

Caries development from 11 to 22 years of age: a prospective radiographic study. Prevalence and distribution.

The aim was to assess the distribution and pattern of caries development longitudinally in teenagers and adolescents whose treatment had been based on remineralizing rather than restorative strategies. A baseline cohort of 536 children was studied, using bite-wing radiographs, from 11 to 22 years of age. The results showed a slow but continuous increase in both enamel and dentin caries of approximal surfaces. At 21, 29% of all posterior approximal surfaces had enamel caries according to the radiographic diagnoses, 14% had dentin caries and another 5% were restored. At the age of 20 21, the skewed distribution of DMFS(appr) apparent at 12 and 15 had given way to a more uniform picture and the percentage of individuals with no decayed approximal surfaces (DMFS(appr) = 0) decreased from 71 at 12-13 to 28 at 20-21 years of age. The proportion of DFS(occl) in relation to all DFS decreased from 83% at 12 to 52% at 21. The occlusal, mesial and distal surfaces of the first molar accounted for 60% of all restored surfaces at 21.

Adolescent↗
PubMed1997

Secondary hyperparathyroidism: pathophysiology, histopathology, and medical and surgical management.

It is generally accepted that morphological changes of the parathyroid glands appear early in renal failure. When diffuse hyperplasia develops into a nodular type, the cells grow monoclonally and proliferate aggressively, with abnormal suppression of parathyroid hormone (PTH) secretion under high extracellular calcium. Based on histopathological and pathophysiological findings, patients with nodular hyperplasia in renal hyperparathyroidism might be refractory to medical treatment, including calcitriol pulse therapy. Thus, parathyroid surgery is indicated for individuals developing hypercalcemia, elevated PTH levels, and/or bone disease, who cannot be effectively treated medically. The detection of enlarged parathyroid glands by image diagnosis is another criterion for surgery. In our experience, parathyroidectomy is an effective treatment; however, the timing of the operation is important, because skeletal deformity and vessel calcification cannot be expected to diminish even after successful surgery. Technically, it is important to identify all parathyroid glands and, in autotransplantation, to use an adequate amount of suitable tissue, namely, a diffuse type of hyperplastic tissue, to guarantee satisfactory postoperative function.

Humans↗
PubMed1997

Increased intramuscular concentration of bradykinin increases the static fusimotor drive to muscle spindles in neck muscles of the cat.

The aim of the present study was to investigate if increased intramuscular concentrations of bradykinin (BK) in one muscle influence the activity in primary and secondary muscle spindle afferents (MSAs) originating from both ipsi- and contralateral muscles, via fusimotor reflexes. The ipsilateral trapezius (TR) and the splenius (SP) muscles were subjected to sinusoidal stretches and 2-3 MSAs were simultaneously recorded from these muscles. Responses of 29 MSAs (15 SP and 14 TR) were registered in five adult cats anaesthetised with alpha-chloralose. Intramuscular injections of 0.5 ml BK (6-86 micrograms/ml) were administered to both the ipsi- and contralateral SP and TR muscles. Similar doses of BK (5-10 micrograms) have been shown to induce muscle pain when injected into the temporal muscle in man. The responsiveness of the MSAs to the injections of BK was 86% and 87.5% from the contralateral TR and SP muscles, respectively. The effects were predominantly static onto the MSAs. The duration of the effects was on average 3.5-4 min, however some effects lasted for more than 15 min. The effects were always abolished after cutting the nerve to the injected muscle. The large majority of the spindle afferents were unresponsive to i.m. Tyrode injections (23 of 29). For the afferents that were responsive to injection of Tyrode, the effects were always considerably smaller and with shorter duration than those evoked by BK injections. Thus, increased intramuscular concentrations of BK may excite primary and secondary MSAs from ipsi- and contralateral muscles, via fusimotor reflexes evoked most probably by activity in chemosensitive muscle afferents. The results are discussed in relation to a recent hypothesis on pathophysiological mechanisms behind genesis, spread and perpetuation of muscle tension and pain in chronic musculoskeletal pain syndromes.

Animals↗
PubMed1997

Apoptosis and growth factors in parathyroid adenomas.

Detection of apoptotic cells and of immunoreactivity to transforming growth factor alpha (TGF-alpha) and to its ligand, epidermal growth factor receptor (EGFR), was studied in 20 cases of parathyroid adenoma. The DNA nick-end labelling method revealed that 85% of these adenomas contained apoptotic cells. Detection rates of TGF-alpha and EGFR were very high, but neither TGF-alpha nor EGFR was correlated to apoptosis. As TGF-alpha exerts its effect via EGFR, the concomitant demonstration of the two factors occurring in both the adenomatous tissue and the surrounding rim of normal tissue may reflect a significant mutual association. The markers were located mainly within the cytoplasm, indicating their important role in growth regulation, cell differentiation and cell function. The synchronous expression of TGF-alpha and EGFR in both parathyroid adenomas and normal glandular parenchyma suggests that these functions may be mediated by an autocrine mechanism.

Adenoma↗
PubMed1997

Exercise tests in large groups of children are not a suitable screening procedure for undiagnosed asthma.

Schoolchildren (n = 473), 12-13 years of age, from five schools, and without known asthma, participated in a screening test for exercise-induced asthma (EIA). The children were tested in large groups of 10-15 pupils. Peak expiratory flow (PEF) was measured before, immediately after, and 6-8 min after 6 min of running exercises in a gymnasium. A fall in PEF of at least 10% on two separate test occasions was considered an abnormal result. Children with abnormal results were given an asthma questionnaire and then tested individually in hospital with a standardized exercise test measuring FEV1, PEF, and flow/volume curve. In the screening test, 23 (4.9%) of the 473 children had an abnormal result. When tested in hospital, five (1%) children had a decrease in PEF and/or FEV1 of at least 10% (10-14%) after exercise. Furthermore, three of these five children had a history indicating mild EIA. We conclude that the use of PEF measurement as a screening method for EIA in large groups of schoolchildren cannot be recommended because it yields many false-positive results.

Adolescent↗
PubMed1997

Complex co-localization of chromogranins and neurohormones in the human gastrointestinal tract.

Co-localization of chromogranin (Cg) A, B, and C has been studied in different neuroendocrine cell types in histologically normal mucosa from human gastrointestinal tract (corpus, antrum, duodenum, ileum, and colon) using single-, double-, and triple-immunofluorescence stainings. Virtually all enterochromaffin (EC) cells contained CgA, and those in the luminal two thirds of the antral mucosa and villi of small intestine often also contained CgB. A few EC cells in the duodenal crypts contained CgC. Most gastrin cells harbored both CgB and CgA, although rather more CgB than CgA, but some gastrin cells contained all three types, i.e., also CgC. Some CCK cells also contained all three chromogranins. Enteroglucagon cells in the duodenal villi contained CgA and some CgB. CgA (but not B or C) was found in some secretin, GIP, enteroglucagon/peptide YY, and neurotensin cells. A few somatostatin cells contained CgA but neither CgB nor CgC. CgA and C were found mainly in the basal cell region, whereas CgB occurred more diffusely throughout the cytoplasm. This varying distribution suggests that not all secretory granules contain CgA, or that CgB may occur in a nongranular form. The varying composition of the different chromogranins may reflect their complex functional roles in the widespread neuroendocrine system.

Cholecystokinin↗
PubMed1997

Influence of hospital- and surgeon-related factors on outcome after treatment of rectal cancer with or without preoperative radiotherapy.

BACKGROUND: Preoperative radiotherapy reduces recurrence rates after surgery for rectal cancer but other variables may also affect outcome. The Stockholm Rectal Cancer Study Group has conducted two prospective randomized trials on preoperative radiotherapy in rectal cancer. METHODS: This study analysed postoperative morbidity and mortality, local recurrence rate and death from rectal cancer in 1399 patients, according to different hospital- and surgeon-related factors. RESULTS: Patients operated on by surgeons who were certified specialists for at least 10 years had a lower risk of local recurrence (relative risk 0.8 (95 per cent confidence interval (c.i.) 0.6-1.0)) and death from rectal cancer (relative risk 0.8 (95 per cent c.i. 0.7-0.9)). The risk was also lower for patients operated on in university hospitals (relative risk of local recurrence 0.7 (95 per cent c.i. 0.5-0.9), relative risk of death from rectal cancer 0.8 (95 per cent c.i. 0.7-1.0)) compared with community hospitals, although the results in some community hospitals were similar to those in university hospitals. The proportional reduction of local recurrence rate after preoperative radiotherapy was not significantly different for the studied institutions and surgeons. CONCLUSION: There was a significant surgeon-related variation in patient outcome, which is probably related to the surgical technique. Although improved technique may reduce the local recurrence rate, preoperative radiotherapy is still beneficial concerning local control and survival.

Adenocarcinoma↗
PubMed1996

Ensemble coding of muscle stretches in afferent populations containing different types of muscle afferents.

Ensemble coding of simple mechanical stimuli (small sinusoidal stretches) was studied in simultaneously recorded mixed ensembles of primary- and secondary muscle spindle afferents (MSAs), and Golgi tendon organ (GTO) afferents recorded from L7-S1 dorsal root filaments. The experiments were made on 48 recorded afferents (29 primary MSAs, 6 secondary MSAs and 13 GTO afferents) in chloralose anaesthetised cats. For the analyses, we used a combination of principal component analysis and algorithms for quantification of stimulus discrimination. Mixed ensembles of primary- and secondary MSAs, and GTO afferents, discriminated significantly better between different muscle stretches than ensembles of only one or two types of these afferents. All kinds of ensembles showed a successive increase in discriminative ability with increased ensemble size and this ability seemed to level at larger populations. However, the increase in discriminative ability was significantly greater for the mixed ensembles. It is hypothesised that the main reason for the greater discriminative ability achieved by mixed ensembles, might be that the variation in response profiles (sensitivity tuning) among the individual afferents of the mixed ensemble will be larger than that for ensembles of only one type of afferent. Finally, the results in the present study give experimental support to some of the teleological arguments in favour of the ensemble coding theory.

Animals↗
PubMed1996

Resection margins of 2 versus 5 cm for cutaneous malignant melanoma with a tumor thickness of 0.8 to 2.0 mm: randomized study by the Swedish Melanoma Study Group.

BACKGROUND: The traditional surgical treatment for primary malignant melanoma has often been a wide excision with a margin of about 5 cm. Since the risk of local recurrences is dependent on tumor thickness, thin tumors (<1 mm) have routinely been excised with a narrow margin. For thick tumors, the optimal resection margin is controversial, and can be determined only by prospective, randomized trials. METHODS: The Swedish Melanoma Study Group performed a prospective, randomized multicenter study to evaluate an excision margin of 2 versus 5 cm for patients with cutaneous malignant melanoma with tumor thickness > 0.8 and < or = 2.0 mm. The trial includes 769 patients. Patients with melanomas of the skin of the head, neck, hands, feet, or vulva were not included in the trial. In the event of an excision biopsy for diagnosis, radical surgery was completed within 6 weeks. The median follow-up time was 5.8 years for estimation of survival and 4.0 years for diagnosis of recurrent disease. RESULTS: No significant differences have been observed between the treatment groups regarding local or regional recurrences or survival. CONCLUSIONS: We recommend an excision with a margin of 2 cm for cutaneous malignant melanoma with a tumor thickness > 0.8 and < or = 2.0 mm.

Biopsy↗