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Biomedical subjects

H Johansson

Publications and source records attributed to H Johansson.

At least 217 records · Page 12Linked to original sources
PubMed1986

Calcium-activated calcium permeability in parathyroid cells.

The Ca2+ receptor mechanism of the parathyroid cell was studied using La3+ as a probe. La3+ was found to bind to the cell surface without further penetration. Measurements of 45Ca fluxes and the cytoplasmic Ca2+ concentration (Ca2+i) revealed a stimulatory component in the action of La3+ on Ca2+ permeability resulting in a rise in Ca2+i. These effects mimicked those obtained when raising the extracellular Ca2+ concentration from 0.5 to 3.0 mM, but the actions of La3+ and Ca2+ were not additive. The results suggest the existence of a novel Ca2+ permeability physiologically activated by binding of Ca2+ to an external receptor.

Animals↗
PubMed1986

Hypertensive crisis immediately after complete removal of phaeochromocytoma.

A hypertensive crisis with an arterial blood pressure of 280/180 mmHg developed immediately after an apparently successful removal of a phaeochromocytoma. The blood pressure could not be lowered by phentolamine and not until the administration of dihydralazine and furosemide was the systemic pressure normalized. In addition to residual high concentrations of vasoactive substances, the hypertension may have been due to an overloaded vascular bed. Careful peroperative volume substitution in patients treated preoperatively with modern sympathetic blocking agents appears to be of great importance.

Adrenal Gland Neoplasms↗
PubMed1986

Histologic parathyroid abnormalities in an autopsy series.

The parathyroid glands from 422 subjects without clinical, biochemical, or advanced histologic signs of renal disease were dissected at autopsy. The glands were evaluated histologically in relation to the subjects' age, sex, histologic renal features, other diseases, and medical therapy. Normal parathyroid glands generally had diffuse cellular arrangements, with variable fat cell content. Increased nodularity was observed, especially in enlarged parathyroid glands. Hyperplasia was present in 7 per cent and adenomas in 2.4 per cent. Hyperplastic glands were often nodular and asymmetric, and numbers of oxyphil cells were frequently increased. Some large nodules were histologically indistinguishable from adenomas. Serum calcium levels were elevated in subjects with adenomas or with hyperplastic glands containing large nodules. The findings seem to indicate that nodularity of the parathyroid tissue is a sign of abnormality and that adenomas may arise from such nodular hyperplasia. Hyperplasia and adenomas were more common in elderly subjects and in those with slight or moderate nephrosclerosis. Other diseases or medical therapy were not found to be correlated with parathyroid weight or histologic features.

Adolescent↗
PubMed1986

Alteration in density, morphology and parathyroid hormone release of dispersed parathyroid cells from patients with hyperparathyroidism.

Dispersed parathyroid cells from normal human and bovine glands and from 10 patients with primary (7 adenomas, 3 hyperplasias) and 4 patients with uraemic hyperparathyroidism (HPT) have been investigated with respect to density, morphology and parathyroid hormone (PTH) release. Percoll density gradients enabled an efficient isolation of viable parathyroid cells which generally banded between 1.035-1.090 g/ml. The average density was significantly higher in cells from the normal than the abnormal glands. The pathological glands contained large chief cells, oxyphil and transitional oxyphil cells and, in one case, water-clear cells which were enriched in fractions with densities below 1.055 g/ml. Measurements of cell diameters revealed an increased proportion of enlarged cells in the preparation of abnormal glands. Nuclear diameters were similar in the normal human glands, adenomas and hyperplasias, but the variability was greater among the adenomas. In comparison to normal bovine parathyroid cells, PTH release of cells from the pathological human glands was reduced and abnormally insensitive to extracellular calcium. The oxyphil and water-clear cells secreted similar amounts of PTH as the chief cells of the abnormal glands. The disturbed PTH release in secondary HPT seemed to be confined mainly to cells within nodules of the hyperplastic glands. The results show that the disturbed hormone regulation in HPT is related to morphological changes of the cells and that buoyant density gradients can be used to accumulate the abnormal cells.

Adenoma↗
PubMed1986

Fusimotor reflexes in triceps surae muscle elicited by stretch of muscles in the contralateral hind limb of the cat.

Experiments were performed on twenty-one cats anaesthetized with alpha-chloralose. The aim of this study was to investigate the reflex effects on triceps surae and plantaris fusimotor neurones elicited by tonic stretch of the contralateral posterior biceps and semitendinosus (p.b.s.t.) and the contralateral triceps surae and plantaris muscles, to compare these effects with the effects evoked by flexion or extension of the intact contralateral hind limb (Appelberg, Hulliger, Johansson & Sojka, 1984) and to clarify the interactions between the reflexes from contralateral and ipsilateral muscles. Activity in fusimotor neurones was studied indirectly by recording from primary muscle spindle afferents of the triceps surae and plantaris muscle. The mean rate of firing and the modulation of the afferent response to sinusoidal extension of the triceps surae and plantaris muscles was determined. Control measurements were made with the ipsilateral p.b.s.t., the contralateral p.b.s.t. and the contralateral triceps and plantaris muscles relaxed. Tests were made with tonic stretch of one of these muscles alone or with two of them simultaneously. With stretch of the contralateral p.b.s.t. ten out of eighty-four primary afferents (11.9%) showed predominantly dynamic reflexes (six out of forty-one in spinalized preparations: 14.6%), twenty-two (26.2%) showed mixed or predominantly static effects (one spinalized: 2.4%) and fifty-two units (61.9%) showed no effect (thirty-four spinalized: 83.0%). The reflex effects could be reproduced by electrical stimulation of the cut contralateral p.b.s.t. nerve either at group II or at group III strength. With stretch of the contralateral triceps and plantaris muscles seventy out of seventy-six (92.1%) primary muscle spindle afferents showed no effect and six (7.9%) mixed or predominantly static reflex effects. In general, the reflex effects were not accompanied by detectable electromyographic (e.m.g.) activity in the ipsilateral triceps and plantaris (recorded with surface or needle electrodes), indicating that the reflexes mainly involved gamma-motoneurones. The difference in efficacy between contralateral flexor (p.b.s.t.) and extensor (triceps and plantaris) muscles seems to be in accordance with the response pattern found with extension or flexion of the intact contralateral hind limb (Appelberg et al. 1984).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Actions on gamma-motoneurones elicited by electrical stimulation of joint afferent fibres in the hind limb of the cat.

Effects on seventy-one single lumbar gamma-motoneurones, evoked by graded electrical stimulation of fibres running in the posterior articular nerve of the ipsilateral knee joint (p.a.n.), were studied by micro-electrode recording in twenty-one cats anaesthetized with alpha-chloralose. Sixty-seven of the gamma-cells were classified indirectly as dynamic (thirty-seven) or static (thirty) using the method of mesencephalic stimulation (cf. Appelberg, Hulliger, Johansson & Sojka, 1982). A high general responsiveness (i.e. number of cells with effect/number of cells tested) was found for the whole sample of gamma-cells (91.9% for dynamic and 93.3% for static cells). The thresholds for the effects were related to the stimulation intensity at which the early negative cord dorsum potential appeared (T). For all subpopulations of gamma-cells (dynamic and static, flexor and extensor cells) excitatory as well as inhibitory effects were observed at 0.9-1.1 T, probably corresponding to 1.1-1.4 times the threshold for evoking a compound action potential in p.a.n. (cf. Discussion). In addition, a considerable number of high-threshold effects were found. Some cells were influenced only from low-threshold joint afferents, some only from high-threshold joint afferents and some cells were influenced from both low- and high-threshold joint afferents. No statistically significant differences in thresholds were found between dynamic and static cells. Among flexor gamma-cells excitatory effects were found to predominate, while for extensor gamma-cells excitation and inhibition occurred with about equal frequency. The shortest latencies for excitatory effects on dynamic gamma-motoneurones were compatible with a trisynaptic pathway, while the routes for excitation of static units and for inhibition of both types of gamma-cells seemed to be longer. The possible functional significance of the findings is discussed. The findings seem to support the idea, as suggested by Freeman & Wyke (1967b), that the joint receptors may contribute to the 'co-ordination of muscle tone in posture and movement' via the gamma-loop. It is furthermore suggested that the latter mechanism may serve to regulate joint stiffness and joint stability.

Action Potentials↗
PubMed1986

Fine needle biopsy and scintigram in the preoperative diagnosis of thyroid lesions.

Fine needle biopsies (FNB) of the thyroid were examined from 860 patients. In 703 cases follicular cells without atypia were found and in this group of patients the clinical diagnosis was nodular goitre. Operations were performed in 138 patients and in 97 cases the cytological finding could be correlated to the histopathological diagnosis. In 33 of these patients thyroid carcinoma was histologically verified. In 26 of the carcinoma cases cytologic examination showed grave atypia or changes indicating carcinoma. The cases in which the cytological diagnoses were falsely negative are discussed. Moderate cellular atypia occurred in one case with papillary carcinoma. In two cases the cytological examination gave a false positive diagnosis of cancer, both representing thyroiditis of the lymphoid type. The scintigrams in patients with thyroid carcinoma are also presented. Cold nodules were found in 10/19 patients and a hot nodule in .1 patient. In 3 patients the scintigrams were normal and in another 5 inconclusive. The results indicate that thyroid scintigrams can only be used as a supplement to the physical examination and a guidance for FNB. The contribution of FNB in the decision to operate is discussed and it is concluded that FNB is a valuable adjunct in preoperative diagnosis of thyroid lesions. The best diagnostic results are obtained when there is a close cooperation between clinician, radiologist, cytologist and pathologist.

Adult↗
PubMed1986

Late results of operation for primary hyperparathyroidism in 441 patients.

The late results of operation for primary hyperparathyroidism (HPT) were analyzed in 441 patients operated on 4 to 27 years earlier (mean follow-up time, 7.7 years). A conservative surgical approach was mainly used, attempting if possible to visualize all four parathyroid glands and extirpate only the enlarged glands. Subtotal resection was performed in patients with hyperplasia. The histopathologic diagnosis was adenoma in 77% and hyperplasia in 18%. In 5% of the patients, the histopathologic classification was uncertain. Hypercalcemia persisted after operation in 8% of all patients. This generally occurred because of an incomplete neck exploration or too limited a resection in the patients with hyperplasia. Recurrent hypercalcemia occurred in 16% of the patients operated on for hyperplasia and was noted 1 to 19 years after surgery. Recurrences were also seen in 3% of the patients with adenomas but not earlier than 9 years after the operation. These findings suggest that primary HPT may even in patients with adenomatous disease, sometimes affect all parathyroid glands. Nevertheless, it was obvious that most of the patients with adenomas would not have benefited from a more radical procedure. On the other hand, it was evidently important to obtain a correct histopathologic diagnosis intraoperatively so that patients with hyperplasia could be identified and adequatley treated.

Adenoma↗
PubMed1986

Adrenal gland surgery. Preoperative location of lesions, histologic findings and outcome of surgery.

The accuracy of various techniques for preoperative location of adrenal lesions was studied in 55 consecutive cases, and the perioperative course and outcome of surgery were analyzed. CT correctly located 94% of all adrenal tumours, was less accurate (42%) in hyperplasia and gave no false-positive results. Selective angiography revealed 75% of the tumours, but was likewise diagnostically inadequate in adrenal hyperplasia. Adrenal venous sampling correctly located 80% of tumours and of hyperplasia. In hyperplasia it was the single most successful procedure for detecting the site of adrenal hyperfunction. Phlebography gave misleading information in almost 45% of cases. The perioperative complications included splenic rupture necessitating splenectomy (3 cases), superficial wound infection (2), pneumonia (4) and subphrenic abscess (1). There were no perioperative deaths. The study indicated CT to be the principal procedure for preoperative location of adrenal disorders. In some cases with adrenal hyperfunction, venous sampling should be added. Adrenal surgery can be performed with low morbidity and no mortality and with favourable long-term outlook in cases of benign lesion.

Adolescent↗
PubMed1985

Paradoxical effects of K+ and D-600 on parathyroid hormone secretion and cytoplasmic Ca2+ in normal bovine and pathological human parathyroid cells.

The effects of K+ and the Ca2+ channel blocker D-600 on parathyroid hormone (PTH) release and cytoplasmic Ca2+ activity (Ca2+i) were measured at different Ca2+ concentrations in dispersed parathyroid cells from normal cattle and from patients with hyperparathyroidism. When the extracellular Ca2+ concentration was raised within the 0.5-3.0 mM range Ca2+i increased and PTH secretion was inhibited. There was also a stimulatory effect of Ca2+ on secretion as indicated by a parallel decrease of Ca2+i and PTH release when extracellular Ca2+ was reduced to less than 25 nM. Addition of 30-50 mM K+ stimulated PTH release and lowered Ca2+i. The effect of K+ was less pronounced in the human cells with a decreased suppressability of PTH release. The Ca2+ channel blocker D-600 had no effect on Ca2+i and PTH release in the absence of extracellular Ca2+. However, at 0.5-1.0 mM Ca2+, D-600 increased Ca2+i and inhibited PTH release, whereas the opposite effects were obtained at 3.0 mM Ca2+. The transition from inhibition to stimulation occurred at a higher Ca2+ concentration in the human cells and the right-shift in the dose-effect relationship for Ca2+-inhibited PTH release tended to be normalized by D-600. It is suggested that K+ stimulates PTH release by increasing the intracellular sequestration of Ca2+ and that the reduced response in the parathyroid human cells is due to the fact that Ca2+i already is lowered. D-600 appears to have both Ca2+ agonistic and antagonistic actions in facilitating and inhibiting Ca2+ influx into the parathyroid cells at low and high concentrations of extracellular Ca2+, respectively. D-600 and related drugs are considered potentially important for the treatment of hyperparathyroidism.

Animals↗
PubMed1985

The effect of truncal vagotomy on serotonin distribution in the rat gastrointestinal tract.

The 5-HT levels in biopsies from the rat gastrointestinal tract were measured by a sensitive liquid chromatography method with electrochemical detection. The highest levels were found in the gastroduodenal and cecal regions. Sham-operated controls were compared with rats subjected to combined truncal vagotomy and pyloroplasty or pyloroplasty alone 5 weeks after surgery. Significantly decreased 5-HT levels were demonstrated in animals subjected to vagotomy + pyloroplasty or to pyloroplasty alone, compared with sham-operated controls. In the upper gastrointestinal tract of vagotomized animals significantly decreased 5-HT levels were found when compared with animals subjected to pyloroplasty alone. However, anesthesia and surgery (sham operation) per se markedly increased 5-HT levels of the gut even 5 weeks postoperatively, when compared with acutely killed rats. The underlying mechanism is still obscure. However, vagotomy largely prevented this increase. Therefore, the importance of correct controls is emphasized, since previous investigations claim to have demonstrated increased 5-HT levels in vagotomized animals, when compared with nonoperated controls.

Animals↗
PubMed1985

Stimulus-secretion coupling of parathyroid hormone release: studies of 45Ca and 86Rb fluxes.

Pieces of rat parathyroid glands were used to study fluxes of 45Ca and 86Rb. The uptake of 45Ca increased with the extracellular Ca2+ concentration up to at least 5 mM. A rise of extracellular Ca2+ had dual effects on 45Ca efflux in terms of an initial stimulation and a subsequent inhibition. However, K+ depolarization neither affected the uptake nor the efflux of 45Ca indicating a lack of voltage-dependent Ca2+ channels. The depolarization obtained with exposure to Ca2+ cannot be attributed to a decreased K+ permeability, since the 86Rb concentrating ability diminished and the efflux of the isotope increased when parathyroid pieces were exposed to a raised Ca2+ concentration. A stimulation of 86Rb efflux by the Ca2+ ionophore A-23187 indicated that the parathyroid cells possess a K+ permeability activated by cytoplasmic Ca2+. It is suggested that Ca2+ fluxes through channels sensitive to activation by Ca2+ are important both for the membrane potential and the cytoplasmic Ca2+ activity.

Animals↗
PubMed1985

Actions on gamma-motoneurones elicited by electrical stimulation of cutaneous afferent fibres in the hind limb of the cat.

The reflex actions elicited by graded electrical stimulation of hind-limb cutaneous (sural, superficial peroneal and tibial) nerves were investigated with intra- and extracellular micro-electrode recordings in gamma-motoneurones projecting to hind-limb muscles in twenty-four cats anaesthetized with alpha-chloralose. In total, reflex responses of 100 gamma-motoneurones were analysed. 82 of the gamma-cells were classified as dynamic (43) or static (39) using the method of mesencephalic stimulation (Appelberg, Hulliger, Johansson & Sojka, 1982). The general responsiveness (i.e. number of input nerves with effect/number of input nerves tested) of the whole sample of gamma-cells to stimulation of skin nerves was extremely high (94.8%). All negative observations were encountered among static and non-classified gamma-cells. Generally, the stimulation strengths needed for evoking effects in the gamma-cells were very low. A majority of the excitatory effects in the dynamic cells appeared with stimulation intensities below 1.5 threshold (T), while most static cells were excited with stimulation strengths between 1.5 and 2 T. Also a statistical comparison of the populations of stimulation strength thresholds for the excitatory effects revealed a significant difference (P less than 0.0009) between dynamic and static gamma-cells. By contrast, the thresholds for inhibitory effects in dynamic cells were slightly higher than for excitatory effects (P less than 0.0009). As regards excitation of static cells, inhibition of dynamic cells and inhibition of static cells, no statistically significant threshold differences were found. A strong dominance of excitation over inhibition was found in both dynamic and static flexor (posterior biceps and semitendinosus) gamma-motoneurones from all input nerves. In comparison to flexor gamma-motoneurones, there was a much higher incidence of inhibitory and mixed (excitatory and inhibitory) responses in extensor (triceps) gamma-motoneurones, from all nerves tested. For dynamic cells there was an about even balance between excitation and inhibition, while for static cells inhibition seemed to prevail. The latencies for excitatory effects in dynamic gamma-cells differed from those in static gamma-cells (P less than 0.027). The shortest latencies of excitatory effects found for dynamic gamma-cells indicate a disynaptic coupling, while for static cells the shortest route seemed to involve at least three synapses.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗