Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 19 recordsLinked to original sources

PubMed1992

[Hepatocellular adenoma after oral contraception].

Raised serum basic phosphatase was found incidentally in a woman aged 43 years. Investigation with biopsy revealed a hepatocellular adenoma. The tumour regressed after withdrawal of Neogentrol oral contraception which the patient had consumed for 17 years. The patient did not desire invasive treatment. Employment of oral contraceptive steroids for more than two years is associated with increased occurrence of hepatocellular adenomata. The hepatocellular adenoma is a clearly delimited, most frequently solitary, benign tumour with limited malignant potential but with a considerable risk of rupture with haemorrhage even after withdrawal of oral contraception. The hepatocellular adenoma has no malignant tumour vessels (in contrast to hepatocellular carcinoma) and it appears as a cold region on scintigraphy (in contrast to focal nodular hyperplasia), but the diagnosis can only be established with certainty by histological examination. The hepatocellular adenoma consists most frequently of large pale hepatocytes in trabeculae surrounded by a net of reticulin and separated by sinusoids. Biliary passage and portal spaces do not occur. The best treatment consists of excision of the tumour or embolisation. If invasive treatment is postponed, regular scanning should be performed to observe regression or progression of the tumour and oral contraception and pregnancy should be advised against on account of the risk of growth of the tumour.

Adult↗

PubMed1992

[Elimination of human chorionic gonadotropin in serum and urine after uncomplicated induced abortion during the first trimester].

Serum chorion gonadotropin was measured weekly in 12 women from the time of legal first trimester abortion until values were below 10 IU/L. The elimination followed a 2-component curve. The half-life in the first few days was 1.1 day, hereafter 4.2 days. Serum-HCG decreased to less than 10 IU/L within 22 to 40 days. The elimination of serum-HCG was found to decrease so uniformly, that values which do not decrease must be considered abnormal. A sensitive bedside urine-HCG test was found to be positive from 13 to 31 days after the abortion.

Abortion, Induced↗

PubMed1992

Age-related alterations in the strength and collagen content of left colon in rats.

The biomechanical properties and intestinal wall composition of left colon were studied in 4-month-old, 14-month-old, and 27-month-old male rats. The hydroxyproline content and hydroxyproline concentration in old rats were increased by 36% and 26%, respectively, compared with young rats and by 20% and 17%, respectively, compared with middle-aged rats. In middle-aged rats the maximum load increased by 21%, compared with young rats. In old rats, however, the maximum load decreased by 13%, compared with middle-aged rats. Histological examination showed that the mean crypt height was 9% higher in middle-aged rats and 12% higher in old rats than in young rats. In conclusion, an accumulation of collagenous proteins was found in old rats compared with middle-aged rats and this was accompanied by a decrease in the strength, which may deteriorate the functional integrity of the left colonic wall with age.

Aging↗

PubMed1992

The ontogeny of the uptake systems for glutamate, GABA, and glycine in synaptic vesicles isolated from rat brain.

The ontogeny of the uptake of glutamate, GABA and glycine into synaptic vesicles isolated from rat brain has been investigated. The vesicular uptake of the three amino acids increased with developmental age in parallel with synaptogenesis, indicating a functional role of uptake of the amino acids by synaptic vesicles in the nerve terminals. Uptake of the amino acids by plasma membrane particles (synaptosomes) in brain homogenate showed a somewhat different developmental profile. The uptake of glutamate increased markedly with developmental time, while the uptake of GABA showed only a slight increase. Uptake of glycine by plasma membrane particles was very low and therefore not registered. The observed developmental increase in uptake of glycine by synaptic vesicles isolated from brain, supports previous reports indicating that glycine can be taken up by vesicles from non-glycine terminals.

Adenosine Triphosphate↗

PubMed1992

Cholinergic 'blockade' as a model of the cognitive deficits in Alzheimer's disease.

The performance of 44 Alzheimer patients and 33 controls was examined on tests previously found to be differentially affected by scopolamine administration. Tests of secondary memory, performance intelligence, primary memory, semantic retrieval, procedural memory and verbal intelligence were included. It was found that Alzheimer patients performed more poorly than controls on tests of secondary memory, as measured by selective reminding, recall and recognition. Procedural memory, as measured by stem completion, homophone spelling and transformed text reading, did not differ between Alzheimer patients and controls. Semantic memory, verbal intelligence and primary memory were impaired in moderate and severe cases. However, patients with 'mild' dementia, as measured by the Mini-Mental State Examination, did not differ from controls on tests of semantic memory, verbal intelligence and primary memory. It was concluded that the pattern of anterograde memory deficits and preserved abilities in mild dementia mimicked that previously observed in scopolamine administration in young subjects.

Aged↗

PubMed1992

Nocturnal variations in human lower leg subcutaneous blood flow related to sleep stages.

Nocturnal subcutaneous adipose tissue blood flow rate was measured in the lower legs of 10 normal human subjects together with systemic arterial blood pressure, heart rate, and registration of sleep stages under ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. The sleep recordings were performed with a portable computerized sleep analysis system. In accordance with the results of previous studies, a hyperemic blood flow rate phase (mean increase 140%) for 100 min was observed approximately 60 min after the subjects went to bed. The moment of onset of the hyperemic phase was closely related to the moment of onset of the first episode of deep sleep (stages 3 and 4). There was a significant (P < 0.01) overrepresentation of deep sleep in the hyperemic phase compared with adjacent phases, and rapid-eye-movement sleep predominantly occurred in the latter part of the night, when the subcutaneous blood flow rate was stable. The results of the present study are in accordance with current theories of the interrelationship between the thermoregulatory and the arousal state control systems and, thus, might suggest that the nightly subcutaneous hyperemia represents a thermoregulatory effector mechanism.

Adipose Tissue↗

PubMed1992

Increased mechanical strength of left colon in old rats treated with growth hormone.

The effects of treatment with 2.7 mg biosynthetic human growth hormone (b-hGH; 2.7 mg/kg b.w./day) for 80 days on the biomechanical properties and collagen deposition of the left colon were studied in 27-month-old male rats. The b-hGH-treated rats increased in body weight by 17%, and the wet weight of colon by 31%. The defatted dry weight and the hydroxyproline content of the left colon were increased by 41 and 29%, respectively, compared with controls. The biomechanical analysis showed that the maximum load and stiffness of the left colonic specimens in the b-hGH-treated group were enhanced by 27 and 60%, respectively, and the strain at maximum load was 24% less than in the control group. The maximum 'stress' and stiffness were 40 and 73% higher, respectively, than in the controls. Histological examination demonstrated that the mean crypt heights was 9% higher in the b-hGH-treated rats than in the controls. Consequently, treatment of old rats with b-hGH may increase the strength, collagen deposition and mucosal crypt height of the left colon.

Aging↗

PubMed1992

Dose-dependent stimulatory effect of human growth hormone on the strength and collagen deposition of colonic anastomoses in the rat.

The effects of treatment with four different doses of biosynthetic human growth hormone (b-hGH; 0.125 mg kg-1 d-1, 0.5 mg kg-1 d-1, 2.0 mg kg-1 d-1, 8.0 mg kg-1 d-1) on the bursting strength and collagen deposition of rat colonic anastomoses were studied. Rats receiving 2.0 mg and 8.0 mg b-hGH demonstrated increases in the pre- and postoperative body weights, and the bursting strength and hydroxyproline content of the anastomotic segments in these groups were significantly higher than controls on day 4 postoperatively. The serum levels of insulin-like growth factor I (IGF-I) were significantly higher than the controls after four days of preoperative treatment in the groups receiving 2.0 mg and 8.0 mg b-hGH, and postoperatively the IGF-I levels were significantly higher than those of the controls in the groups receiving 0.5 mg, 2.0 mg and 8.0 mg b-hGH per kg. Consequently, positive correlations were found between treatment doses of b-hGH and anastomotic defatted dry weight, hydroxyproline content and bursting strength of colonic anastomoses.

Anastomosis, Surgical↗

PubMed1992

Serum amylase levels in gynecologic patients with acute abdominal pain.

Total amylase and salivary (S) type isoamylase were measured in serum from 80 women with acute abdominal pain admitted to the Department of Gynecology. Fifty-seven patients had verified gynecologic diseases, including 21 patients with inflammation of the internal genitals and 11 with ectopic pregnancy. Twelve patients had an intrauterine pregnancy in the first trimester. None of the 80 patients showed hyperamylasemia.

Abdominal Pain↗

PubMed1991

The ontogeny of the uptake systems for glycine, GABA and glutamate in synaptic vesicles isolated from rat spinal cord-medulla.

Synaptic vesicles have been isolated from rat spinal cord-medulla at different postnatal ages, and the ontogeny of the uptake of glycine, gamma-aminobutyric acid (GABA) and glutamate has been investigated. The accumulation of the 3 amino acids increased with increasing time after birth reaching adult level at about postnatal day 30. This developmental increase probably parallels the synaptogenesis and suggests a functional role of the uptake of the amino acids into synaptic vesicles in the nerve terminals. The developmental time course for these vesicular uptake systems was totally different from those of the corresponding plasma membrane uptakes.

Aging↗

PubMed1991

Uptake of glycine, GABA and glutamate by synaptic vesicles isolated from different regions of rat CNS.

Synaptic vesicle fractions have been isolated from cerebral cortex, subcortical telencephalon, whole brain and spinal cord by density gradient centrifugation. The Mg2+ ATP-dependent vesicular uptake and the Na(+)-dependent synaptosomal uptake of glycine, GABA and L-glutamate has been compared in the different regions. All these regions contain GABA as inhibitory neurotransmitter, whereas glycine only plays a dominant role as such in the spinal cord. The ratio between GABA and glycine uptake in the different vesicle fractions was similar, and the ratios differed greatly from the ratios in the synaptosomal uptake. In contrast, the ratio between glutamate and GABA uptake in vesicles from different regions differed, and these ratios corresponded to the ratios in the synaptosomal uptake. These results indicate that glycine is taken up into synaptic vesicles from non-glycine terminals, and we suggest that GABA and glycine can be taken up into the same vesicle population.

Adenosine Triphosphate↗

PubMed1991

Inhibition of gamma-aminobutyrate and glycine uptake into synaptic vesicles.

The substrate specificity of vesicular GABA and glycine uptake was studied in vesicle fractions from brain and spinal cord, respectively. Glycine, beta-alanine and gamma-vinyl-GABA were competitive inhibitors of the GABA uptake were competitive inhibitors of the GABA uptake by synaptic vesicles in brain. Likewise GABA and beta-alanine turned out to be competitive inhibitors of vesicular uptake of glycine in spinal cord. The apparent K1 values were in the same range as the respective Km values for the transport systems. Accumulation of different amino acids were examined, and the structurally related amino acids GABA, beta-alanine and glycine were all taken up by both vesicle fractions. In the present study, we suggest that there are similarities in the vesicular transporters for GABA and glycine, and the two amino acids are probably taken up into the same vesicle population. The key factor in differentiating between GABA and glycine as transmitters in the terminals could be the synthesis and the high-affinity synaptosomal uptake.

Alanine↗

PubMed1991

Molten globule intermediates and protein folding.

The background to the concept of the term "molten globule" as a description of intermediates observed in the folding of globular proteins is discussed. These compact intermediates are characterised by certain properties including the presence of secondary structure and considerable conformational mobility compared to the native, functional state. Those intermediates that are thermodynamically stable under mild denaturing conditions have many features in common with the transient intermediates that accumulate significantly during the process of folding. Attention is drawn to cases where the two types are however distinguished on grounds of their Stokes radius, in which cases there is currently no direct evidence for the involvement of the stable intermediates on the folding pathway. Experimental evidence relating to the early stages in folding is reviewed and compared, highlighting the temporal relationship between general collapse of the polypeptide chain and the formation of secondary structure. The continued use of the term "molten globule" is recommended where the minimum essential structural criteria for this state are met.

Animals↗

PubMed1991

Postoperative biosynthetic human growth hormone increases the strength and collagen deposition of experimental colonic anastomoses.

This study examined the effects of preoperative treatment with 2.0 mg biosynthetic human growth hormone (b-hGH)/kg/day on the bursting strength and collagen deposition of experimental left colonic anastomoses, and of intact colon from sham-operated rats. The anastomotic bursting pressure was 55% higher in the b-hGH treated animals on day 2 (p less than 0.05) and 79% higher on day 4 (NS; p = 0.056), and the bursting wall tension was 65% higher on day 2 (p less than 0.05) and 112% higher on day 4 postoperatively (p less than 0.05), than saline-injected controls. The hydroxyproline content of the anastomotic segment in the b-hGH treated rats increased by 56% on day 4 (p less than 0.005) and by 30% on day 6 postoperatively (p less than 0.05), compared with controls. At 3 cm proximal to the anastomoses the defatted dry weight and hydroxyproline content of the healing colons were increased after 6 days compared with the sham-operated rats. There was, however, no difference between the b-hGH treated rats and the paired controls, indicating that growth hormone is not involved in this process.

Anastomosis, Surgical↗

PubMed1991

Explicit and implicit memory in dementia and normal ageing.

In two experiments, young subjects, healthy elderly subjects (spouses), and highly intelligent elderly subjects (elite elderly), were compared with dementia patients in a variety of explicit and implicit memory tasks, to investigate two issues: whether priming in Alzheimer-type dementia is contingent upon the presence of pre-existing representations, and whether intelligence modulates performance in explicit memory tasks in healthy ageing. Dementia patients performed as well as spouses in a homo-phone-spelling task. Moreover, they established new contextual associations when memory was tested by word-stem completion. The hypothesis that priming in dementia is contingent upon pre-existing memory representations was not supported. Spouses, elite elderly, and young subjects did not differ in their ability to recognize correctly recently heard stimuli or to complete word stems. However, recall of lists of words and paired associates was better in both young and elite elderly subjects than in spouses. It is concluded that intellectual capacity rather than chronological age in healthy subjects modulates performance in explicit-memory tasks.

Aged↗

PubMed1991

Is age kinder to the initially more able? A study of eminent scientists and academics.

Elderly eminent academics and blue-collar workers were compared with Doctor of Philosophy students and trade apprentices to investigate whether intelligence and memory deteriorate at a slower rate in persons with high ability. The elderly groups showed decline on tests of perceptual-motor speed, visuospatial reasoning, inferential thinking and memory relative to the young subjects. Initial ability determined the level of intellectual performance, such that elderly academics maintained their initial advantage over the elderly blue-collar workers. However, with the exception of the Similarities subtest of the Wechsler Adult Intelligence Scale, the rate of change on tests of memory and intelligence did not differ for the high- and low-ability groups. The hypothesis that high ability is associated with a slower rate of cognitive decline was not supported.

Academies and Institutes↗

PubMed1991

Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans.

Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease in mean arterial blood pressure (P less than 0.001) were observed. The duration of this hyperemic phase was 116 min. A highly significant reduction of the subcutaneous vascular resistance (50%) was demonstrated during the hyperemic blood flow rate phase compared with the surrounding phases (P less than 0.0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.

Adult↗

PubMed1991

Bronchodilator and corticosteroid reversibility in ambulatory patients with airways obstruction.

With the aim of characterising subgroups, we analysed reversibility tests from 1,048 patients with airways obstruction (baseline FEV1 less than 60% of predicted normal (%pred), and FEV1 to FVC ratio less than 0.6). Spirometry before and after inhalation of salbutamol 0.3 mg and ipratropium bromide 0.06 mg was performed before and after one week of treatment with prednisone 30 mg daily. The changes in FEV1 after bronchodilators showed unimodal distribution (mean = 7.0 %pred, st.dev. = 6.6 %pred). The responses to corticosteroid were more spread out (mean = 6.3 %pred, st.dev. = 13.8 %pred). The correlation between bronchodilator responses before and after corticosteroid treatment was poor (r = 0.30), although highly significant (p less than 0.000,001). The responses to bronchodilators were virtually independent of the steroid reversibility. The corticosteroid response was inversely related to age (r = -0.20, p less than 0.000,001) and smoking habits (r = -0.17, p less than 0.000,001), and moderately associated with blood eosinophilia (r = 0.34, p less than 0.000,001). The frequency distribution of the bronchodilator responses and the steroid response and combinations of the responses were all unimodal, making any distinction between nosologic subgroups arbitrary. It is clear from the study that criteria other than just response to therapy must be employed for distinction of subgroups among patients with airways obstruction.

Adolescent↗