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Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 235 records · Page 13Linked to original sources

Epidemiology of domestic burns related to products.

Of 4357 home accidents in a 1-year period related to products, a total of 338 burn injuries were prospectively studied with respect to age, sex, the time and cause of the burn accident and the product involved in the burn injury. The survey showed the highest incidence (26 per cent) in the age group 0-5 years and that most burns were caused by scalds or contact. The male to female ratio was 1:1. Activities related to cooking and making/drinking hot beverages constitute the majority of the domestic burns. A trend of more burns occurring during the weekends and the dark winter was found, but monthly or seasonal differences were not significant (0.10 less than P less than 0.20 and 0.20 less than P less than 0.30).

Accidents, Home↗

Endurance capacity and longevity in women.

The aim of our study was to compare the cardiovascular and metabolic adjustments of 8 female and 8 male subjects to similar situations of physical stress, which involved muscle contractions at various intensities, and to link the results with the fact that in Scandinavia, women survive men by an average of 5-10 years. The mean age of subjects was 25 years old, and all were in good health. It was concluded that the cardiovascular and metabolic reactions to comparable regimens of physical stress differ markedly between female and male subjects: The women demonstrated the healthier adjustments, with lesser blood pressure elevation and a higher degree of lipid utilization. Both reactions are linked to protective mechanisms with respect to developing ischemic heart disease. We suggest that these adjustments are linked to longevity in women, and that part of the explanation of the sex differences in physiological adjustments to physical stress and in longevity lies in the fact that women through life are subjected to a higher degree of physical activity.

Adult↗

Treatment of panic and agoraphobia. An integrative review.

There is now agreement about the clinical features of panic disorder and agoraphobia but less agreement about treatment because of controversy over whether the disorder is primarily biological or psychological. The authors were requested to produce an impartial review for continuing education and peer review. We chose to do this by using a quantitative review procedure, by providing a bibliography of studies, and by a literature review. We found that symptoms of panic and phobia did not change significantly while on wait-list control or while receiving placebo. The evidence for the efficacy of the low-potency benzodiazepines or of monoamine oxidase inhibitors was limited. It was also clear that only limited improvement can be expected from behavior therapies that do not involve exposure to the symptoms of panic or to the feared situation. Symptoms of panic, as well as the frequency of spontaneous panic, were shown to be substantially improved following imipramine, high-potency benzodiazepines such as alprazolam, exposure in vivo (especially if a cognitive anxiety management procedure was used), and the combination of imipramine and exposure in vivo. The effects on panic produced by the exposure therapies (with or without imipramine) were maintained over long follow-up periods. Imipramine, alprazolam, exposure therapy, and imipramine plus exposure each produced significant improvements in phobias. In the short term and in the long term, the larger improvements in phobias were associated with exposure therapy, particularly if used in combination with imipramine. We conclude that it would be unwise to theorize about the etiology of this disorder on the basis of response to a specific treatment because, both at the meta-analytic level and from the review of individual studies, it is clear that both drug and nondrug therapies can produce substantial and long-lasting changes in panic and in phobias.

Agoraphobia↗

Uptake of glycine into synaptic vesicles isolated from rat spinal cord.

Glycine was taken up by a synaptic vesicle fraction from spinal cord in a Mg-ATP-dependent manner. The accumulation of glycine was inhibited by carbonyl cyanide-m-chlorophenylhydrazone (CCCP) and nigericin, agents known to destroy the proton gradient across the vesicle membrane. Vesicular uptake of glycine was clearly different from synaptosomal uptake, with respect to both the affinity constant and the effect of Na+, ATP, CCCP, and temperature. Oligomycin and strychnine did not inhibit the vesicular uptake, showing that neither mitochondrial H(+)-ATPase nor binding to strychnine-sensitive glycine receptors was involved. It is suggested that the vesicular uptake of glycine is driven by a proton gradient generated by a Mg2(+)-ATPase. A low concentration of Cl- had little effect on the uptake of glycine, whereas the uptake of glutamate in the same experiment was highly stimulated. High concentrations of gamma-amino-n-butyric acid and beta-alanine inhibited vesicular glycine uptake, but glutamate did not. Accumulation of glycine was found to be fourfold higher in a spinal cord synaptic vesicle fraction than in a vesicle fraction from cerebral cortex.

Adenosine Triphosphate↗

Hypothalamic-pituitary and thyroid function in chronic alcoholics with neurological complications.

Endocrinological tests were performed in 14 chronic alcoholic men with signs of intellectual impairment and/or peripheral neuropathy. All had been abstinent from alcohol for at least 1 month. Basal serum growth hormone (GH) was consistently increased in only one patient whereas the GH responses to insulin hypoglycemia stimulation was normal in all patients. Thyroid function values (T4, T3, rT3, TSH) were normal in all patients whereas baseline serum prolactin values were significantly increased in alcoholics as compared with a control group. In a combined TRH- and GnRH-stimulation tests, GH-responses were also normal whereas TSH and prolactin responses were blunted or absent in about half of the patients, the responses correlating significantly (p less than 0.01). It is concluded that disturbances in the hypothalamic-pituitary axis may occur in chronic alcoholics with nervous impairment independently of the physical deterioration, which often is associated with chronic alcoholism.

Adult↗

Growth hormone increases the mass, the collagenous proteins, and the strength of rat colon.

The effect of growth hormone treatment on the left colon was investigated in 4-month-old Wistar rats. The animals were injected with saline (controls) or biosynthetic human growth hormone (b-hGH) in doses of 1.0 and 5.0 mg b-hGH/kg/day for 30 days. The total body weight of the rats injected with 1.0 mg b-hGH/kg/day did not differ from that of the control group, whereas the body weight of the rats injected with 5.0 mg b-hGH/kg/day was increased by 37% compared with the control group. The colonic dry weight per unit length was increased by 57% and 46% by 1.0 mg and 5.0 mg b-hGH/kg/day, respectively. The defatted dry weight was increased by 52% and 44%, respectively. The hydroxyproline content per unit length was increased by 31% and 23%, respectively. Furthermore, the biomechanical strength was increased by the b-hGH injections. No difference between the two b-hGH doses was found in any of the data.

Animals↗

Three highly sensitive "bedside" serum and urine tests for pregnancy compared.

We examined three enzyme-linked immunosorbent assay (ELISA) kits for human choriogonadotropin (hCG) (pregnancy tests) for use with urine and serum samples: the Tandem Icon II hCG Urine and Tandem Icon II hCG Serum, the NovoClone Target hCG Test, and the Abbott TestPacks hCG-urine and hCG-serum. Paired comparison of the results from each kit indicated that the NovoClone Target assay showed significantly lower diagnostic sensitivity (P less than 0.05) than did the Tandem Icon II or Abbott TestPack, both for urine and for serum samples. None of the products demonstrated any significant difference (P greater than 0.05) in diagnostic specificity, but the NovoClone Target kit showed several serious false-negative results with both urine and serum. Paired testing of urine kits vs serum kits also showed no significant differences (P greater than 0.05) in diagnostic sensitivity or specificity. We found the Abbott kits to be the most convenient to use and to read.

Adult↗

Ultrastructural study of acinar and intercalated duct organization of submandibular and parotid salivary gland.

According to some current hypotheses, the morphology and organization of the intercalated duct/acinar interface of salivary gland have implications for the induction of tumors in this organ. However, this region has received limited detailed investigation. To study the organization of the terminal ductal segments of salivary gland, conventional transmission electron microscopy of human parotid and submandibular glands and canine submandibular gland was combined with 3-dimensional observations of polymer casts of the canine submandibular ductal system; the latter were prepared by retrograde injection of acrylic resin via the main excretory duct with subsequent digestion of the gland tissue. The division of intercalated ducts, into first- and second-order branches, and acinar arrangement is more complex than previously suggested. The entire surface of each elongated second-order intercalated duct is covered with acini projecting in all directions. In the human gland, some acini abut directly on the intercalated duct surface, whereas others are connected by a short stalk of intercalated duct cells; in comparison with canine submandibular gland, the latter may be a modification producing a third-order of the intercalated duct unit. All of these features combine to produce a highly efficient secretory apparatus with a large proportion of acinar cells to each intercalated duct.

Animals↗

Power spectrum analysis of the EMG pattern in normal and diseased muscles.

The diagnostic value of analogue frequency analysis of EMG from patients with neuromuscular disorders has not been convincing. Using fast Fourier transformation it is today possible to obtain the EMG power spectrum on-line and with a better resolution. We examined the power spectrum of the EMG pattern of the brachial biceps muscle in 20 control subjects, 20 patients with myopathy, and 12 with neurogenic disorders. The electrical activity was sampled with a concentric needle electrode from 10 sites in each muscle. From each spectrum, mean power frequency, the power at 140 Hz, 1400 Hz, 2800 Hz and 4200 Hz relative to total power and the high/low ratio (1400/140) were obtained. The mean power frequency was higher at 10% than at 30% of maximal force. At a force of 30% of maximum the power spectrum analysis identified 55% and 64% of the patients with myopathy and neurogenic disorders, respectively. Although the diagnostic yield of the power spectrum analysis at a force of 10% of maximum was less than that at 30%, additional patients were identified at 10% increasing the diagnostic yield to 65% and 73% for patients with myopathy and neurogenic disorders, respectively. The best diagnostic parameters were the mean power frequency and the relative power at 1400 Hz.

Adolescent↗

Comparison of the properties of gamma-aminobutyric acid and L-glutamate uptake into synaptic vesicles isolated from rat brain.

Rat brain synaptic vesicles exhibit ATP-dependent uptake of gamma-[3H]amino-n-butyric acid ([3H]GABA) and L-[3H]glutamate. After hypotonic shock, the highest specific activities of uptake of both L-glutamate and GABA were recovered in the 0.4 M fraction of a sucrose gradient. The uptakes of L-glutamate and GABA were inhibited by similar, but not identical, concentrations of the mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone and the ionophores nigericin and gramicidin, but they were not inhibited by the K+ carrier valinomycin. N,N'-Dicyclohexyl-carbodiimide and N-ethylmaleimide, Mg2+-ATPase inhibitors, inhibited the GABA and L-glutamate uptakes similarly. Low concentrations of Cl- stimulated the vesicular uptake of L-glutamate but not that of GABA. The uptakes of both L-glutamate and GABA were inhibited by high concentrations of Cl-. These results indicate that the vesicular GABA and L-glutamate uptakes are driven by an electrochemical proton gradient generated by a similar Mg2+-ATPase. The vesicular uptake mechanisms are discussed in relation to other vesicle uptake systems.

Adenosine Triphosphate↗

Effects of oral terbutaline in chronic airflow limitation.

A randomized, double-blind, crossover study was conducted to assess the efficacy of five weeks' treatment with terbutaline, 15 mg daily, compared with placebo in 17 evaluable patients with moderate to severe chronic airflow limitation (CAL) with a minor reversible component. A significant improvement after terbutaline treatment compared with placebo was observed in subjective assessments of breathlessness after two of the activities of daily living, and in daily peak flow measurements recorded in patient diaries. At the clinical assessment after five weeks' terbutaline therapy, 12 of 17 patients had improved pulmonary symptom scores compared with placebo, and a slight increase in FEV1 was observed relative to placebo (0.09 L, p less than 0.05). Thus, five weeks' treatment with oral terbutaline in patients with CAL resulted in significant improvements in several subjective assessments, despite a lack of effect on the majority of the objective variables.

Administration, Oral↗

Lesion of the ligamentum bifurcatum in ankle sprain.

In a consecutive study of 106 patients with a history of ankle sprain, 40.5% showed clinical signs of damage to the ligamentum bifurcatum of the midfoot. A significantly larger percentage of these patients complained of maximum tenderness localized to the instep compared with the patients without signs of damage to the ligamentum bifurcatum (P less than 0.001). Radiologic examination revealed 20 lesions related to damage to the ligamentum bifurcatum: laxity in the transverse tarsal joint, 12; avulsion from the anterior process of the calcaneus, 5; avulsion from the cuboid, 2; avulsion from the navicular, 1. The clinical importance of these findings is debatable. Previous investigations have revealed hypermobile ankles in patients with laxity in the transverse tarsal joint, as well as long convalescence time and risk of nonunion in patients with fractures of the anterior process of the calcaneus. It is therefore recommended that patients with a history of ankle sprain be evaluated concerning damage to the ligamentum bifurcatum of the midfoot.

Adolescent↗

Quantitative surface EMG during sustained and intermittent submaximal contractions.

In an earlier occupational study the EMG was found to be unchanged during a whole working day. The purpose of this study was therefore to examine EMG changes during experiments in a laboratory environment comparable to occupational work. The surface EMG of the quadriceps muscle of 16 subjects was analysed during 3 experiments: (I) 10% maximal voluntary contraction (MVC) sustained for 1 h, and with a constant work intensity of the muscle; (II) 20% MVC for 5 sec alternating with a rest of 5 sec for 1 h; (III) 20% MVC was sustained until exhaustion. In the latter the endurance time decreased with increasing MVC. The results indicated that the methods used in this study can be trusted to reveal changes in EMG due to fatigue in a group of subjects but not in the individual subject. The decrease in mean power frequency (MPF) and the increase in root mean square amplitude (RMS) were most pronounced during the first 10 min of the 10% sustained contraction, indicating a decrease in the conduction velocity along the muscle fibres or synchronization of motor unit firing. In contrast, at 20% intermittent contraction the MPF was unchanged. Between 10 and 60 min of contraction time the increase in RMS amplitudes associated with none or only slight changes in MPF indicated recruitment of new motor units for both types of contraction. The lack of EMG fatigue during a whole day in an earlier occupational study may be because the work performed required varying degrees of muscle force.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗