Biomedical subjects

J Nielsen

Publications and source records attributed to J Nielsen.

At least 325 records · Page 18Linked to original sources

PubMed1990

Mortality and cancer morbidity in workers exposed to low levels of vinyl chloride monomer at a polyvinyl chloride processing plant.

To study whether exposure to low levels of vinyl chloride monomer (VCM) causes increased risk for cancer morbidity and death from ischemic heart disease, a cohort study was performed among 2,031 male workers at a polyvinyl chloride (PVC) processing plant who had been employed for at least 3 months during the period 1945-1980. An almost significantly increased total mortality (SMR = 116, 95% CI 99-136) was found. Deaths caused by violence or intoxication were significantly increased (SMR = 153, 95% CI 109-213), but not deaths from ischemic heart disease (SMR = 100, 95% CI 73-135). A significant increase in total cancer morbidity was observed (SMR = 128, 95% CI 101-161). Respiratory cancers were significantly increased (SMR = 213, 95% CI 127-346). Furthermore, six brain tumors (vs. 2.6 expected) were observed. This increase, however, was not significant (SMR = 229, 95% CI 84-498). No liver hemangiosarcoma was observed. Applying a latency period of greater than or equal to 10 years from start of employment did not change the risk patterns. There were no significant exposure-response associations between exposure estimates for VCM, asbestos, and plasticizers and cancer morbidity.

Adult↗

PubMed1990

Sensitivity of monosynaptic test reflexes to facilitation and inhibition as a function of the test reflex size: a study in man and the cat.

In parallel experiments on humans and in the cat it was investigated how the sensitivity of monosynaptic test reflexes to facilitation and inhibition varies as a function of the size of the control test reflex itself. In man the monosynaptic reflex (the Hoffmann reflex) was evoked in either the soleus muscle (by stimulation of the tibial nerve) or the quadriceps muscle (by stimulation of the femoral nerve). In the decerebrate cat monosynaptic reflexes were recorded from the nerves to soleus and medial gastrocnemius muscles; they were evoked by stimulation of the proximal ends of the sectioned L7 and S1 dorsal roots. Various excitatory and inhibitory spinal reflex pathways were used for conditioning the test reflexes (e.g. monosynaptic Ia excitation, disynaptic reciprocal inhibition, cutaneous inhibition, recurrent inhibition, presynaptic inhibition of the Ia fibres mediating the test reflex). It was shown that the additional number of motoneurones recruited in a monosynaptic test reflex by a constant excitatory conditioning stimulus was very much dependent on the size of the test reflex itself. This dependency had the same characteristic pattern whatever the conditioning stimulus. With increasing size of the test reflex the number of additionally recruited motoneurones first increased, then reached a peak (or plateau) and finally decreased. A similar relation was also seen with inhibitory conditioning stimuli. The basic physiological factors responsible for these findings are discussed. Finally, the implications for the interpretation of experiments in man with the H-reflex technique are considered.

Adolescent↗

PubMed1990

Biological monitoring of isocyanates and related amines. II. Test chamber exposure of humans to 1,6-hexamethylene diisocyanate (HDI).

Five male subjects were exposed to 1,6-hexamethylene diisocyanate (HDI) atmospheres for 7.5 h. The exposures were performed in an 8 m3 stainless steel test chamber, and the HDI atmospheres were generated by a gas-phase permeation method. HDI in air was determined by an HPLC method utilizing the 9-(N-methylaminomethyl)-anthracene reagent, and by a continuous monitoring device (MDA 7100). The average air concentration was ca 25 micrograms/m3, and the inhaled dose of HDI for the different subjects was estimated at ca 100 micrograms. The related amine 1,6-hexamethylene diamine (HDA) was after acid hydrolysis of urine and plasma, determined as a heptafluorobutyric derivative, by glass capillary gas-chromatography and selected ion monitoring (SIM), in a chemical ionization mode using ammonia as reagent gas. The cumulated urinary excretion of HDA during 28 h was 8.0 to 14 micrograms, which corresponds to ca 11 to 21% of the inhaled dose of HDI. The urinary level of HDA, in samples collected immediately after the end of the exposures, was on average 0.02 mmol/mol creatinine (range 0.01-0.03 mmol/mol creatinine). The urinary elimination was rapid, and half-time (t 1/2), for the concentration of HDA in urine, showed an average of 1.2 h (range 1.1-1.4 h). No specific IgE and IgG antibodies to HDI were detected before and after provocation; nor were spirometry or bronchial reactivity changed immediately and 15 h after provocation. Analysis of HDA in hydrolysed urine, as a marker of short-time exposure to HDI, is proposed.

Adult↗

PubMed1990

Coital frequency and twinning.

In a comparative study to enquire whether parents of twins, especially of dizygotic twins, have a higher frequency of sexual intercourse than parents of singleton infants, data on sociodemographic status, coital frequency and other variables were collected using a postal questionnaire. Parents of all twins born alive in Denmark in 1984 or 1985 were included as cases and a random sample of parents of singleton infants born in the same period were controls. No evidence of any difference in coital frequency was found between parents of twins (neither dizygotic twins nor monozygotic) and parents of singleton infants.

Adult↗

PubMed1990

Total i.v. anaesthesia with propofol-alfentanil or propofol-fentanyl.

In combination with propofol, alfentanil was compared with fentanyl for total i.v. anaesthesia in 29 women (ASA classes I, II) admitted for elective hysterectomy. Infusion rates of propofol and fentanyl were determined from the literature and from pilot studies, while alfentanil was given according to a computer program. Dosage was: propofol, bolus 1.5 mg kg-1, infusion 9 mg kg-1 h-1 for 10 min and thereafter 6 mg kg-1 h-1; fentanyl, bolus 7.5 micrograms kg-1, infusion 15 micrograms kg-1 h-1 reduced successively to 1.8 micrograms kg-1 h-1; alfentanil, bolus 60 micrograms kg-1, infusion 240 micrograms kg-1 h-1 reduced successively to 100 micrograms min-1. Induction was smooth and maintenance easy to manage in both groups. Plasma concentrations were stable with a ratio of alfentanil to fentanyl of 100:1. Recovery times were equal and short, but recovery tests performed 3 h after operation showed that alfentanil produced a greater effect on ability to concentrate and fine co-ordination.

Adult↗

PubMed1990

Specific antibodies to methyltetrahydrophthalic anhydride in exposed workers.

A group of 145 workers exposed to methyltetrahydrophthalic anhydride (MTHPA) was investigated. They were working in a plant which, since 1983, handled an epoxy resin with MTHPA as a hardener. Specific IgE antibodies (RAST) to a conjugate between MTHPA and human serum albumin (HSA) were statistically significantly increased (P = 0.001; 26 subjects = 18% positive) in the exposed group, compared to a non-exposed control group (n = 33). One positive worker was only exposed for 2 months. Twenty-three exposed subjects were also skin-prick test positive to MTHPA-HSA. The exposed group was divided into three different exposure categories, according to their contact with the epoxy resin. The average exposure levels at the time of the investigation were, in zone I 0.085 mg/m3, in zone II 0.014 mg/m3, and in zone III 0.010 mg/m3, though the exposure probably had been higher earlier. There was an association between exposure intensity and RAST-positive persons (P = 0.0025, chi-square trend test). Forty-four persons (30%) were smokers, and 16 (11%) atopics. No association between sensitization and either atopy or smoking was found. There was an association between exposure intensity and specific IgG antibodies (P = 0.0003, chi-square trend test). Specific IgG4 antibodies were closely related to specific total IgG antibodies (P = 0.0001). These findings demonstrate that MTHPA is a sensitizing agent at low levels of exposure.

Antibody Specificity↗

PubMed1990

Standards for growth and final height in Turner's syndrome.

Data on birth, growth and final height were collected retrospectively for 78 women with Turner's syndrome born 1955-66. Seventy-one had received estrogen treatment from a mean age of 17.7 years (SD = 2.0 years), while 7 were spontaneously menstruating. At birth Turner girls were 440 g lighter (p less than 0.001) and 1.4 cm shorter (p less than 0.001) than 46,XX girls. Standards for untreated growth were established for the age period 6.5-17.5 years, while growth after 17.5 years was described in both untreated and estrogen treated women. Analysis of growth pattern showed that though no pubertal growth spurt was present, the steady decrease of height velocity (HV) was interrupted at the age of 9 years. HV was then constant until 12 years of age, whereafter it slowly decreased. Mean final height (FH) was 146.8 cm (SD = 5.8 cm, n = 76) compared to 166.8 cm in the general female population. No difference was found between 45,X women and women with other karyotypes (p greater than 0.7). Correlations between FH and parental heights, birthweight and birthlength were similar to those reported for normal women (19). FH varied with age at diagnosis. Those diagnosed after 17 years of age had a mean FH = 151.3 cm, while those diagnosed before had a mean FH = 145.8 cm (p less than 0.001).

Adolescent↗

PubMed1990

Regional variations in analgesic efficacy of EMLA cream. Quantitatively evaluated by argon laser stimulation.

The effect of EMLA cream (a eutectic mixture of local analgesics) applied for 30, 60, 90 and 120 min on the forehead, cheek, back, cubital fossa, and dorsum of the hand was studied. Analgesic onset, efficacy and duration were evaluated by sensory and pain thresholds to laser stimulation measured before, and 5, 60, 120, and 180 min after the cream was removed from the skin. Cutaneous blood flow was measured and found to be 4-5 times as high on the face as on the other locations. On the forehead the analgesic efficacy decreased with increased application time. For all other locations, efficacy increased with increasing application time. On the back, onset was rapid and sufficient analgesia could be obtained, but analgesias began to wane immediately after removal of the cream. In the cubital fossa and on the hand, onset was tardy, and efficacy continued to increase for 60 min after cream removal, followed by a slow decline. Blood flow, epidermal and dermal thickness are important factors affecting onset, efficacy and duration of EMLA analgesia.

Adult↗

PubMed1990

Follow-up of 25 unselected children with sex chromosome abnormalities to age 12.

Twenty-five unselected children with sex chromosome abnormalities have been followed to a mean age of 12 years. The IQ distribution was slightly below the normal level at the age of 4 to 7, but at the age of 8 to 11 the IQ distribution had improved to within normal limits. We interpret this to be due to the provision of information and counseling to the parents, and use of all available resources for stimulation of the children, including both parental resources and kindergarten, school, and social system resources. All the children attended regular schools. Remedial teaching was given to slightly more than one-third of the children in mathematics and reading. The children were average or above average at school, irrespective of karyotype, if they had a very good home with parents who had been willing and able to follow our counseling, and if the children had been given stimulation, remedial teaching, and speech therapy as and when needed. Parents with a child with a sex chromosome abnormality usually need information, counseling, and assistance. The type and magnitude of this assistance depend on the individual child, the specific sex chromosome anomaly, and the parents' own resources, psychologically, socially, and otherwise.

Adolescent↗

PubMed1990

Sex chromosome abnormalities found among 34,910 newborn children: results from a 13-year incidence study in Arhus, Denmark.

A 13-year incidence study of sex chromosome abnormalities in Arhus, Denmark of 34,910 newborn children showed that 1 per 448 had a sex chromosome abnormality. The incidences of the most common sex chromosome abnormalities were Klinefelter syndrome, 1 per 576 boys; XYY, 1 per 851 boys; triple X, 1 per 897 girls; Turner syndrome, 1 per 2130 girls. Follow-up of children with autosomal abnormalities is not included in this study. None of the 78 surviving children with sex chromosome abnormalities was mentally retarded. All children above school age attended regular schools. Seventy-seven percent of Klinefelter, triple X, and XYY children aged 15-19 had received remedial teaching, 29% were receiving remedial teaching at the last follow-up, 32% had been in special classes at a regular school due to learning problems, and 24% were still in such classes at the last time of follow-up. There was no increased frequency of criminal activity or behavior disorders, nor was there any increased frequency of mental or physical disorders. The distribution of planned training or occupation for the 25 youths with sex chromosome abnormalities between 15 and 19 years of age was similar to that of their sibs. Testosterone undecanoate treatment has been given to Klinefelter boys from puberty and growth hormone treatment to Turner girls from the age of 7, and very small doses of estrogen were given to these girls from around the age of 12 when FSH was increasing to postmenopausal levels. Prevention or reduction of deviations in mental development from the normal range in children with sex chromosome abnormalities is possible if educational and social resources are available and the parents are well informed and counseled regularly. Information in Denmark has been given in part by publishing four booklets about triple X, XYY, Turner, and Klinefelter syndrome. Information, support, and stimulation to self-help have, to a certain extent, been given through contact groups. Parents having a child with a sex chromosome abnormality need information, counseling, and assistance. The type and magnitude of this assistance depend on the individual child, the specific sex chromosome abnormality, and the parents' own resources, psychologically, socially, and otherwise.

Aneuploidy↗

PubMed1990

The parental origin of the extra X chromosome in 47,XXX females.

We used X-linked DNA polymorphisms to study the parental origin of X chromosome nondisjunction in 28 47,XXX live-born females. Errors in oogenesis accounted for 26 of the cases, with the majority of these being attributable to an error at meiosis I. We observed an association between advanced parental age and meiosis I nondisjunction--but not meiosis II nondisjunction--in the maternally derived cases. In studies of recombination we found little evidence for an association between pairing failure and X chromosome nondisjunction, but our results suggest that increased recombination near the centromere may play a role in the etiology of the 47,XXX condition.

Adolescent↗

PubMed1989

[The relation of birth weight and gestational age in a group of infants in Jutland with special reference to diagnosing infants with intrauterine growth retardation].

The relationship between birthweight (BW) and gestational age (GA) in 14,276 Danish children with GA of 35 to 42 completed weeks was illustrated employing 10%, 50% and 90% percentile curves. The curves were sex-specific. The number of light for dates (LFD) children defined by means of the 10% percentile (BW below 10th percentile) was 1,351 compared to 848 children when using the curve currently employed. The latter curve was based upon foreign children and moreover was not sex-specific. It is concluded that sex-specific and updated curves representing the population studied are mandatory in the diagnosis of LFD-children.

Birth Weight↗

PubMed1989

[A study of percutaneous absorption of estradiol and progesterone in absolute alcohol in postmenopausal women].

Absorption of solutions containing 17-beta-oestradiol (E2) in absolute alcohol and progesterone (P) in absolute alcohol was investigated in six postmenopausal women. These preparations were applied to the skin of the forearm and the abdomen. 1 mg E2 was applied twice daily to the left forearm (RAS) for 28 days. After an interval of one week, the treatment was continued with 1 mg E2 twice daily for 28 days in the epigastric region (RE). From the 14th to the 28th day, this treatment was supplemented by 10 mg P twice daily partly on the right forearm and partly on the epigastrium. The 24-hour absorptions of E2 and P were investigated: E2 on the first and fourteenth days and P on the fourteenth day in both periods. On days 1, 7, 14, 21 and 28, plasma E2, oestrone (E1) and oestrone sulphate (E1SO4) were investigated for hormone application. Statistically significant absorption of E2 was found after 24 hours (p less than 0.05) and significantly greater absorption from RAS than RE (p less than 0.005). No systematic variation in plasma E2 was found during the period of investigation on RAS or RE. P was not absorbed. No local side effects were registered. It is concluded that E2 dissolved in absolute alcohol is clinically employable for treatment of postmenopausal women but that P is of no value in the dosage employed here. Further investigations of transcutaneous absorption of P are desirable.

Administration, Cutaneous↗

PubMed1989

[Breech presentation deliveries].

A total of 5,519 consecutive single deliveries at term were analysed for maternal and foetal factors associated with breech presentation (UK). The protocol in this department for breech deliveries which permits vaginal delivery of foetuses estimated to be between 2,400 and 3,800 g in cases where the pelvis was considered to be clinically normal, was also evaluated. Breech presentation was found in 173 cases. In 102 of these circumstances were present which permitted trial of vaginal delivery. Seventy-seven were delivered vaginally. An increased frequency of low Apgar scores (less than 8) after one minute was demonstrated among infants delivered vaginally in the breech presentation on comparison with infants delivered by Caesarean section, whereas low scoring after five minutes occurred with the same frequency. One infant died during delivery. Follow-up of infants delivered in breech presentation (mean period of observation two years) showed developmental disturbances in three of the vaginally delivered infants and in five of those delivered abdominally. Two of the infants delivered abdominally had severe cerebral paresis and psychomotor retardation without evidence of intrauterine or severe neonatal asphyxia. On comparison with the population delivered in cephalic presentation (HST), significantly increased frequencies of primiparity and light-for-dates infants were found in the breech presentations. Low Apgar score after one minute was significantly more frequent in breech presentations while low Apgar scoring after five minutes occurred with the same frequency. The perinatal mortality rates in breech and cephalic presentations were 17.3 and 4.7 per 1,000 respectively. Following correction for lethal malformations, the rates were 5.8 and 3.8 per 1,000, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Apgar Score↗

PubMed1989

Methodological implications of the post activation depression of the soleus H-reflex in man.

A long lasting inhibition (greater than 8 s) of the soleus Hoffmann reflex (H-reflex) was evoked by a preceding soleus H-reflex, by a brief voluntary ankle flexor or extensor muscle contraction or by a tap applied to the Achilles tendon. The time course of this long lasting inhibition was similar in all these cases, suggesting that the same spinal mechanism is involved. Furthermore, it was shown that the post-activation depression may interfere with the determination of inhibitory or facilitatory effects on the H-reflex. It is stressed that when the onset of inhibitory or facilitatory effects on the soleus H-reflex is to be determined in relation to start of an ankle movement, either very long stimulus intervals (greater than 8 s) must be used, or the onset must be determined in relation to a reference value of the soleus H-reflex, which may be influenced by the long lasting inhibitory effect, but not yet by the succeeding muscle contraction.

Adult↗

PubMed1989

Small airways function in workers processing polyvinylchloride.

In a polyvinyl chloride (PVC) processing plant, 20 workers employed as machine attendants and calender operators, and thus exposed to PVC thermal degradation products (PTDP) and phthalic acid esters (PAE; up to 2 mg/m3), were studied. The control group was 19 unexposed workers. The exposed subjects had more symptoms from eyes and upper airways than the controls, probably mainly associated with PTDP. Two (10%) exposed workers had mild work-related asthma vs no control; five (25%) vs one (5%) symptoms of unspecific bronchial hyperreactivity. One exposed subject had a significantly raised level of IgG against phthalic anhydride, indicating that sensitization can occur in PVC processing. No significant differences were found between exposed and control subjects with regard to spirometry (VC, FEV1, FEF50, FEF75) or volume of trapped gas (VTG, an indicator of small airways disease) before or after metacholine inhalation. Thus, we could not find effects of PTDP or PAE on the small airways.

Adult↗

PubMed1989

Infection studies in mink with seal-derived morbillivirus.

Morbillivirus derived from diseased harbour seals (Phoca vitulina) has characteristics of acute virulent canine distemper virus infection in mink. The infection induced a disease resembling the acute systemic and nervous form of canine distemper.

Animals↗

PubMed1989

Lymphokine activated killer (LAK) cells in antibody dependent cellular cytotoxicity (ADCC) using MAb 17-1A: a combination of potential usefulness in tumor therapy.

Peripheral blood lymphocytes (PBL) stimulated by interleukin-2 (IL-2) for 48-96h, generated killer cells against the human colon cancer cell line SW948. The killing capacity increased significantly when the specific mouse monoclonal antibody (MAb) 17-1A was present during the lytic process. The chimeric antibody 17-1A determined a significantly stronger cytotoxicity compared to mouse MAb 17-1A. MAb BR55-2 which recognizes a different antigen on SW948 target cells mediated a similar cytotoxicity as MAb 17-1A. Presence of alpha-interferon (IFN) during the lytic assay significantly enhanced the killing of the tumor by lymphokine activated killer (LAK) cells as well as by LAK cells and mouse MAb 17-1A. However, when chimeric MAb 17-1A and LAK cells were used alpha-IFN failed to increase the lytic activity, probably due to already maximum lysis in the system. Combinations of various biological response modifiers such as monoclonal antibodies, IL-2/LAK cells and alpha-IFN carry great promise to improve this kind of therapy for cancer patients.

Animals↗