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Biomedical subjects

J Hansen

Publications and source records attributed to J Hansen.

At least 19 recordsLinked to original sources

Formaldehyde and cancer morbidity among male employees in Denmark.

Formaldehyde, a genotoxic and potent animal carcinogen, is widespread in the working environment as well as in private homes. The risk for cancer morbidity in Denmark during 1970-84 was estimated from standardized proportionate incidence ratios (SPIR) among men whose longest employment had been held since 1964, at least 10 years before diagnosis, in 265 companies in which exposure to formaldehyde was identified. The results do not support the hypothesis that formaldehyde is associated with lung cancer (SPIR = 1.0, 410 cases). Significantly elevated risks were found for cancers of the colon (SPIR = 1.2, 166 cases), kidney (SPIR = 1.3, 60 cases), and sino-nasal cavities (SPIR = 2.3, 13 cases). For sino-nasal cancer, a relative risk of 3.0 (95 percent confidence interval = 1.4-5.7) was found among blue-collar workers with no probable exposure to wood dust, the major confounder. This study provides further evidence that occupational exposure to formaldehyde increases the risk for sino-nasal cancer.

Adult

HIV protease inhibitor HOE/BAY 793, structure-activity relationships in a series of C2-symmetric diols.

A detailed structure-activity relationship of C2-symmetric diol inhibitors of HIV-1 protease leads to inhibitor 6 (HOE/BAY 793) which is outstanding in the inhibition of the enzyme and in the inhibition of viral replication in HIV infected cell culture (IC50: 0.3 nM; EC50: 3 nM). There are well defined steric requirements for the design of the side chains P1-P3 of the inhibitors. In addition, all three side chains need to be lipophilic. While the enzyme tolerates hydrophilic substituents in some cases, drastic reductions in anti-HIV activity are observed in cell culture, most likely due to insufficient cell penetration.

Carbon

Cancer incidence in men with Klinefelter syndrome.

Many case reports have suggested an association between Klinefelter syndrome (KS) and cancer, but studies of the cancer incidence in larger groups of men with KS are lacking. A cohort of 696 men with KS was established from the Danish Cytogenetic Register. Information on the cancer incidence in the cohort was obtained from the Danish Cancer Registry and compared with the expected number calculated from the age, period and site specific cancer rates for Danish men. A total of 39 neoplasms were diagnosed (relative risk = 1.1). Four mediastinal tumours were observed (relative risk = 67); all four were malignant germ cell tumours. No cases of breast cancer or testis cancer were observed. One case of prostate cancer occurred within a previously irradiated field. No excess of leukaemia or lymphoma was found. An increased risk of cancer occurred in the age group 15-30 years (relative risk = 2.7). All six tumours in this group were germ cell tumours or sarcomas. The overall cancer incidence is not increased and no routine cancer screening seems to be justified. A considerably elevated risk of mediastinal germ cell tumours occurs in the period from early adolescence until the age of 30.

Adolescent

Selective miscarriage of Down's syndrome fetuses in women aged 35 years and older.

OBJECTIVE: To estimate the fetal loss of Down's syndrome fetuses between the time of chorionic villus sampling (10 weeks gestation) and the time of amniocentesis (16 weeks gestation) and term in women aged 35 years and older. DESIGN: The age specific prevalence rates in the first trimester of Down's syndrome were estimated using the Danish cytogenetic register in combination with results from four published studies. These were compared with the reported prevalence at the time of amniocentesis and at birth. SUBJECTS: 5927 singleton pregnancies undergoing chorionic villus sampling (71 cases of Down's syndrome and 5856 unaffected cases). This was combined with published data on a further 231 cases of Down's syndrome and 16,620 unaffected cases. MAIN OUTCOME MEASURES: Age specific prevalences at the time of chorionic villus sampling. Proportion of pregnancies lost between the time of chorionic villus sampling and the time of amniocentesis and term. RESULTS: Thirty-two percent of Down's syndrome pregnancies are lost between the time of chorionic villus sampling (10 weeks) and the time of amniocentesis (16 weeks) and 54% are lost by term. CONCLUSIONS: The high fetal loss rates of Down's syndrome between the time of chorionic villus sampling and term introduce problems when evaluating first trimester screening tests with respect to their effective detection rates at term. A recommendation for quoting term risks is made.

Abortion, Spontaneous

Increased adhesion as a mechanism of antibody-dependent and antibody-independent complement-mediated enhancement of human immunodeficiency virus infection.

Enhancement of human immunodeficiency virus (HIV) infection by complement alone or in conjunction with antibodies was studied experimentally and theoretically. Experimental studies showed that while HIV-positive sera neutralize HIV infection, the addition of fresh complement abrogated neutralization and could even cause enhancement. Enhancement was blocked by anti-complement receptor 2 antibodies, and infection under enhancing conditions could be blocked by soluble CD4. Antibody-dependent complement-mediated enhancement (C'ADE) was dependent on the alternative complement activation pathway, as factor B-deficient serum could enhance only after the addition of factor B. The observed enhancement was also antibody dependent, since the addition of antibodies increased the level of enhancement. Under C'ADE conditions, infection reached a plateau within 5 min and was not caused by activation of cells by factors in the human serum. On the contrary, preincubation of cells with complement decreased the level of enhancement. A theoretical model of HIV infection in vitro which exhibited similar enhancement in an antibody- and complement concentration-dependent way was developed. Model studies indicated that the enhanced infection process could be explained by the fact that virions, because of complement deposition on the surface, bind more efficiently to cells. The model also indicated that the saturation of the enhanced infection process seen after a few minutes could be caused by saturation of the complement receptors. The effect of neutralizing antibodies can thus be overcome by the enhancing effect of complement that facilitates the contact between gp120 and CD4. These studies demonstrate that the main features of the complement-dependent enhancement phenomenon can be understood in terms of a simple mathematical model.

CD4 Antigens

Skeletal muscle vascular responses in human limbs to isometric handgrip.

Studies of whole limb blood flow have shown that static handgrip elicits a vasodilatation in the resting forearm and vasoconstriction in the resting leg. We asked if these responses occur in the skeletal muscle vascular bed, and if so, what is the relative contribution of local metabolic versus other mechanisms to these vascular responses. Blood flow recordings were made simultaneously in the skeletal muscle of the resting arm and leg using the Xenon-washout method in ten subjects during 3 min of isometric handgrip at 30% of maximal voluntary contraction. In the arm, skeletal muscle vascular resistance (SMVR) decreased transiently at the onset of exercise followed by a return to baseline levels at the end of exercise. In the leg SMVR remained unchanged during the 1st min of handgrip, but had increased to exceed baseline levels by the end of exercise. During exercise electromyography (EMG) recordings from nonexercising limbs demonstrated a progressive 20-fold increase in activity in the arm, but remained at baseline in the leg. During EMG-signal modelled exercise performed to mimic the inadvertent muscle activity, decreases in forearm SMVR amounted to 57% of the decrease seen with controlateral handgrip. The present study would seem to indicate that vascular tone in nonexercising skeletal muscle in the arm and leg are controlled differently during the early stages of static handgrip. Metabolic vasodilation due to involuntary contraction could significantly modulate forearm skeletal muscle vascular responses, but other factors, most likely neural vasodilator mechanisms, must make major contributions. During the later stages of contralateral sustained handgrip, vascular adjustments in resting forearm skeletal muscle would seem to be the final result of reflex sympathetic vasoconstrictor drive, local metabolic vasodilator forces and possibly neurogenic vasodilator mechanisms.

Adult

Cancer morbidity among employees in a Danish pharmaceutical plant.

BACKGROUND: Workers in the pharmaceutical industry may be exposed to many potential carcinogens. We investigated cancer morbidity in a Danish plant where enzymes, insulin, antibiotics and sex hormones were produced in substantial quantities. METHODS: Altogether 10,889 people ever employed (1964-1988) at the pharmaceutical plant were retrieved from the files of a compulsory pension fund, and followed-up in the nationwide Danish Cancer Registry (1964-1989). Site-specific standardized incidence ratios (SIR) were estimated, based on cancer rates for the national population. Information on risk factors for breast cancer, e.g. number of children, age at menarche and first delivery, obesity, and non-occupational use of sex hormones was obtained from samples of the female employees, and compared to equivalent variables from the general population. RESULTS: The overall SIR for women was significantly elevated (n = 5554; SIR = 1.2). Excess risk was particularly seen for breast cancer (n = 97; SIR = 1.5), especially in a subgroup who had started work at the factory aged 30-39 and had continued to work for 1-9 years (SIR = 2.8). The SIR was near unity for men (n = 5335); however, three men with breast cancer versus 0.4 expected were found. Lifestyle components explained only about one-quarter of the excess female breast cancers. Proxy measures of intensity of occupational exposure to sex hormones or insulin showed no association with the risk for breast cancer. CONCLUSIONS: It seems unlikely that either a single occupational factor or an unusual reproductive pattern can explain the elevated breast cancer risk. Therefore, the finding requires further study.

Adolescent

Direct measurement of sympathetic activity: new insights into disordered blood pressure regulation in chronic renal failure.

The ability to record sympathetic nerve activity in conscious human subjects using intraneural microelectrodes (microneurography) has proven to be a powerful clinical research tool, which has shed new light on the pathophysiology of important blood pressure problems as exemplified in studies of patients with chronic renal failure. Hypertension is present in the majority of hemodialysis patients and is a major risk factor for their excessive mortality from heart attack and stroke. Microneurographic studies indicate that there is a neurogenic component to this hypertension. In addition, severe episodic hypotension is an important complication of maintenance hemodialysis. Microneurographic studies have advanced the concept that abrupt paradoxical withdrawal of sympathetic vasoconstrictor drive is an important cause of this episodic hypotension. These microneurographic data provide the conceptual framework for systematic assessment of new therapeutic strategies.

Humans

Two divergent MET10 genes, one from Saccharomyces cerevisiae and one from Saccharomyces carlsbergensis, encode the alpha subunit of sulfite reductase and specify potential binding sites for FAD and NADPH.

The yeast assimilatory sulfate reductase is a complex enzyme that is responsible for conversion of sulfite into sulfide. To obtain information on the nature of this enzyme, we isolated and sequenced the MET10 gene of Saccharomyces cerevisiae and a divergent MET10 allele from Saccharomyces carlsbergensis. The polypeptides deduced from the identically sized open reading frames (1,035 amino acids) of both MET10 genes have molecular masses of around 115 kDa and are 88% identical to each other. The transcript of S. cerevisiae MET10 has a size comparable to that of the open reading frame and is transcriptionally repressed by methionine in a way similar to that seen for other MET genes of S. cerevisiae. Distinct homology was found between the putative MET10-encoded polypeptide and flavin-interacting parts of the sulfite reductase flavoprotein subunit (encoded by cysJ) from Escherichia coli and several other flavoproteins. A significant N-terminal homology to pyruvate flavodoxin oxidoreductase (encoded by nifJ) from Klebsiella pneumoniae, together with a lack of obvious flavin mononucleotide-binding motifs in the MET10 deduced amino acid sequence, suggests that the yeast assimilatory sulfite reductase is a distinct type of sulfite reductase.

Amino Acid Sequence

Inhibition of alpha 2-adrenergic vasoconstriction during contraction of glycolytic, not oxidative, rat hindlimb muscle.

Previous studies have produced conflicting evidence as to whether sympathetic vasoconstriction is impaired in active skeletal muscle. Because alpha 2-, not alpha 1-, adrenergic vasoconstriction is attenuated by mild acidosis, we hypothesized that alpha 2-mediated sympathetic vasoconstriction would be attenuated in contracting glycolytic muscle, which produces more acidosis than oxidative muscle. We compared effects of lumbar sympathetic nerve stimulation and alpha-adrenergic agonists on arterial pressure, femoral blood flow, and force output during contractions of oxidative or glycolytic muscles in anesthetized rats. We found that 1) sympathetic vasoconstriction was preserved during contractions of oxidative soleus muscle and during low-intensity contractions of glycolytic gastrocnemiusplantaris muscles but was abolished during maximal contractions of these glycolytic muscles; 2) this sympatholytic effect was caused by impaired alpha 2-, not alpha 1-, vasoconstriction; and 3) the increased muscle blood flow resulting from a combination of impaired vasconstriction and increased arterial pressure was paralleled by increased force of gastrocnemius-plantaris muscle contraction. Thus contraction-induced impairment of alpha 2-vasoconstriction can augment muscle blood flow and muscle contraction, but the degree of impairment depends on fiber type and intensity of muscle contraction.

Adrenergic alpha-Agonists

[Pharmacological treatment of benign prostatic hyperplasia].

Over the last five to ten years, new treatment modalities have appeared at an increasing pace. The emerging pharmacological treatment modalities have all been used on a large scale. The exact indications and limitations of these methods have not yet been definitely established. Careful analysis of the symptomatology is crucial in counseling the patient. The Danish Prostatic Symptom Score model (DAN-PSS) is proposed. However, treatment benefits should exceed harm and there must be a reasonable cost-effectiveness. Pharmacological agents that reduce prostatic size and/or the tone in the prostate are effective in treatment of benign prostatic hyperplasia. Selective alpha-1 blockers seem to be useful in patients with uncomplicated benign prostatic hyperplasia and mild to moderate symptoms. The side effects of hormone therapy are prohibitive for use in patients with a benign disease. Data currently available indicate a yet to be defined role for 5-alpha-reductase inhibitors.

Adrenergic alpha-Antagonists

Autologous transplantation with peripheral blood mononuclear cells collected after administration of recombinant granulocyte stimulating factor.

Peripheral blood mononuclear cells (PBMC) were collected after the administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and used as the sole source of hematopoietic stem cells after myeloablative therapy with busulfan (Bu) and cyclophosphamide (Cy). These studies were performed in 12 patients with malignancies (4 non-Hodgkin's lymphoma, 5 breast cancer, 1 testicular carcinoma, 1 Wilm's tumor, and 1 undifferentiated carcinoma) who had bone or bone marrow disease or had low marrow cellularity. rhG-CSF (16 micrograms/kg/d) was administered for 5 to 7 days by subcutaneous injection and PBMC were collected for 2 to 5 days beginning on day 4 after initiation of rhG-CSF, using continuous-flow blood-cell separators that processed 10 to 12 L of whole blood. From a median of three collections, a mean of 24.0 x 10(8) (+/- 10.5 SD) total nucleated cells/kg containing 12.6 x 10(8) (+/- 4.5 SD) mononuclear cells/kg, 7.3 x 10(6) (+/- 4.3 SD) CD34+ cells/kg and 20.5 x 10(4) (+/- 28.1 SD) granulocyte-macrophage colony-forming units (CFU-GM)/kg were harvested and cryopreserved. After the administration of Bu 14 to 17 mg/kg and Cy 120 to 150 mg/kg, PBMC were thawed and infused. One patient received rhG-CSF after the infusion of PBMC and the remaining 11 patients did not receive postinfusion growth factors. Mean days to recovery of neutrophil levels of 0.1, 0.5, and 1.0 x 10(9)/L were 11.4 (range, 9 to 13), 12.7 (range, 10 to 15), and 13.6 (range, 11 to 16) and the mean day to platelet transfusion independence was 13.3 (range, 7 to 49). Time to recovery of neutrophils to 0.5 and 1.0 x 10(9)/L and platelets to 20 x 10(9)/L was more rapid than in historical patients treated with Bu and Cy who received marrow alone or marrow followed by the posttransplant administration of rh-G or GM-CSF. No graft failures have been observed with a follow-up of 4 to 12 months. These results indicate that PBMC collected after rhG-CSF lead to rapid hematopoietic recovery after myeloablative chemotherapy.

Antigens, CD

Synthesis and collagenase inhibition of new glycosides of aranciamycinone: the aglycon of the naturally occurring antibiotic aranciamycin.

Glycosides of aranciamycinone were prepared by glycosylation with sugar acetates and trimethylsilyl triflate in dichloromethane. Glycosides of the following sugars were prepared: alpha-L-rhamnopyranose, beta-D-glucopyranose, beta-D-ribopyranose, beta-D-xylopyranose, alpha-L-fucopyranose, 2-azido-2,6-dideoxy-alpha-L-mannopyranose, 2,6-dideoxy-alpha-L-arabino-hexopyranose, 3,6-dideoxy-alpha-L-arabino-hexopyranose, and 4,6-dideoxy-alpha-L-lyxo-hexopyranose. The new glycosides were tested for inhibition of Clostridium histolyticum collagenase and Yoshida Sarcoma tumor cells.

Animals

Inhibition of collagenase by aranciamycin and aranciamycin derivatives.

Aranciamycin (1), an anthracycline antibiotic, was found to be an inhibitor of Clostridium histolyticum collagenase, with an IC50 = 3.7 x 10(-7) M. Elastase and trypsin were not inhibited at concentrations less than or equal to 10(-5) M. A number of aranciamycin derivatives 2-13 were prepared and tested for collagenase inhibition. While loss of activity was found for derivatives modified in the sugar ring or rings B and D of the aglycone, increased potency was found when the tertiary alcohol at C-9 was esterified. All compounds 1-13 were found to inhibit DNA synthesis of Yoshida sarcoma tumor cells.

Animals