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Biomedical subjects

H Michels

Publications and source records attributed to H Michels.

At least 55 records · Page 3Linked to original sources
PubMed1990

Autoantibodies to nonhistone chromosomal proteins HMG-1 and HMG-2 in sera of patients with juvenile rheumatoid arthritis.

IgG antibodies against the high mobility group (HMG) nonhistone chromosomal proteins HMG-1 and/or HMG-2 were detected in the sera of 49 (39%) of 126 antinuclear antibody (ANA)-positive patients with juvenile rheumatoid arthritis (JRA), by immunoblotting. Clinical diagnosis classified these patients in 2 major groups, 105 with pauciarticular-onset JRA and 21 with polyarticular-onset JRA. Anti-HMG-1 and/or anti-HMG-2 antibodies were found in 8 (25%) of 32 pauciarticular-onset JRA patients with uveitis and in 34 (47%) of 73 patients without uveitis, whereas anti-HMG-1 and/or anti-HMG-2 antibodies were found in 4 (24%) of 17 children with polyarticular-onset JRA without uveitis. Among 53 sera from ANA-negative JRA patients, 3 (6%) were positive for anti-HMG-1 and/or anti-HMG-2 antibodies, whereas no reactivity to HMG-1 or HMG-2 proteins was observed in 48 sera from age-matched children with nonrheumatic diseases.

Adolescent↗
PubMed1988

Thyroid hormone response to thyrotropin releasing hormone after cold treatment during pre- and postnatal development in the domestic fowl.

The purpose of the present study was to compare the effect of periodic cooling during the establishment of a functional pituitary-thyroid axis at days 11-14 of incubation and at other developmental stages, on the subsequent thyroid hormone response to thyrotropin releasing hormone (TRH). In the first and second experiment chick embryos were cooled for 6 hr/day to 30 degrees C from day 11 till 14 and from day 15 till 18 respectively, whereas control groups were incubated throughout at 37.8 degrees C. In both experiments the thyroxine (T4) response upon TRH in 19 day-old embryos was higher in the previously cold treated embryos, according to the percentages of increase. However, the higher T4 response in the cold treated animals disappeared in 1 or 7 day-old chicks hatched from the 2nd experiment, but remained present in chicks of the same ages in the 1st experiment. In a third experiment the T4 response to TRH injection immediately and 3 and 8 days after a temperature treatment (25 degrees C or 12 degrees C) for one week on four weeks old broiler chickens was found to be similar in both temperature groups. In all experiments there was a concomitant triiodothyronine (T3) increase after TRH injection, but differences between experimental groups were observed at days 15 and 19 of incubation and immediately after the postnatal temperature treatment. As an overall conclusion the results indicate that cold treatment only during the establishment of the hypothalamo-hypophysial control of thyroid function can have a long lasting effect by enhancing the T4 response to TRH injection.

Animals↗
PubMed1988

[The metaraminol provocation test in the diagnosis of familial Mediterranean fever].

Familial Mediterranean Fever (FMF) is a cyclic inflammatory disease of unknown pathogenesis and autosomal recessive inheritance. Diagnosis is notoriously difficult by the lack of specific signs or laboratory tests although early diagnosis is mandatory to avoid developmental delay or possibly fatal amyloidosis by treatment with colchicine. In adults, Metaraminol Provocative Test (MPT) has been described as specific and highly sensitive in the diagnoses of FMF. We tested 18 children, 9 of whom suffered from FMF. They were ill for 5 years and had been treated as in-patients for 3 months without improvement (median values). 5 of the children with FMF had a positive test results. 4 children with FMF were negative. All 9 children with other disorders were negative, too. During the course of diagnosis, they had been suspected of suffering from FMF. So, in childhood, MPT is specific for FMF but does not identify all children with FMF. However, a positive MPT may be a great help in diagnosing FMF.

Child↗
PubMed1987

Five year follow-up of a prospective cohort of juvenile chronic arthritis with recent onset.

One hundred and fifty children with unsuspected juvenile chronic arthritis (JCA) and a disease duration of 3-6 months entered a prospective study. Diagnosis of JCA could be verified in 107 patients according to the WHO-EULAR criteria. After 5.0 +/- 0.9 years 66 of the 107 patients showed no disease activity, 24 of them for more than 2 years, 23 for less than 2 years without any drug therapy. Nineteen patients were still on NSAIDs and/or long acting drugs, 14 patients with unfavourable morphologic outcome (greater than stage II) and 17 patients with severe functional impairment (greater than or equal to stage III) all belonged to the 41 children with still active disease after 5 years follow-up. The disease course was polyarticular in 10 of the 14 patients with severe radiologic changes and in 14 of the 17 with unfavourable functional results. The wrist joint proved especially vulnerable since 46% of the severe radiologic changes concerned this joint. All 4 children with positive rheumatoid factor followed a polyarticular course with severe radiologic changes (stage greater than II), 3 of them together with unfavourable functional outcome. Risk factors for morphologically and functionally unfavourable course are therefore seen in a still active disease after 5 years, a polyarticular joint involvement and a positive rheumatoid factor. Extra-articular complications concerned chronic iridocyclitis in 7 patients, acute iridocyclitis in 2, amyloidosis in 1 and growth retardation in 2 children. -The prospective study is to be continued.

Adolescent↗
PubMed1987

Effect of exogenous LH on plasma concentrations of progesterone and oestradiol in relation to the cessation of egg laying induced by different moulting methods.

Artificially induced cessation of egg laying caused regression of the reproductive tract in hens, as well as changes in circulating concentrations of sex steroids. Hens were bled at several stages during and after artificial moult induced by fasting or overfeeding a diet low in calcium or high in zinc. Hens received a single injection of 200 i.u. of horse LH at Day 0, 7, 21, 35 and 77 (Exp. 1) or Day 0, 8, 23, 35 and 71 (Exp. 2) after start of the treatment to induce moult. Blood samples were taken before and 20, 40 and 60 min (Exp. 1) or 15, 30 and 45 min (Exp. 2) after LH injection. Hens which were fasted or given the diet high in zinc had low plasma progesterone concentrations and the response to LH was reduced or delayed. In hens fed low calcium the reduction in plasma progesterone was less pronounced and the responsiveness to LH was more or less maintained. Conversely, there was no response of oestradiol to LH in laying hens. However, oestradiol concentrations increased in moulting hens after LH injection, due to the high oestradiol secretion from the small white follicles, since all yolky follicles were atretic.

Animals↗
PubMed1986

[Prospective observation study on the clinical course of chronic juvenile arthritis (JCA)].

A non-randomized follow-up study of 106 children with juvenile chronic arthritis was conducted for two years starting from the onset of the disease. All subgroups - with the exception of seropositive polyarthritis - showed a decrease in the number of joints affected, and activity of the disease in a number of patients. Instant remission and therapeutic effects cannot distinctly be differentiated. Radiological changes are proper criteria for early diagnosis in children with intense progressive joint-findings. X-ray examinations of the joints affected are therefore indicated at regular intervals especially, in the seropositive, occasionally in the seronegative polyarthritic subgroup.

Arthritis, Juvenile↗
PubMed1985

Long-term effect of incubation temperatures on production parameters and changes in luteinizing hormone and gonadal steroids during the onset of lay in the hen.

Earlier studies demonstrated that different incubation temperatures (33.8 or 37.8 C) from Day 17 of incubation until hatching resulted in differences in postnatal growth rate and hormonal parameters. These studies were repeated and extended to the reproduction period. The onset of egg laying was significantly delayed by 5 days in the 33.8 C group compared to the 37.8 C group. No differences in percent egg production were found between the groups after 3 or 5 months of production: however, mean egg weight was significantly reduced in the 33.8 C group by 1.9 and 1.8 g over 3 and 5 months of production, respectively. Serum concentrations of luteinizing hormone (LH), estradiol (E2), estrone (E1), progesterone (P4), and testosterone (T) were measured weekly at the same time of day approximately 4 weeks before to 4 weeks after the onset of lay. The changes in levels of all hormones over the period studied were identical for both experimental groups. Luteinizing hormone, T, and E2, but not E1 and P4, were different before and after onset of lay in both groups. There were no significant correlations between hormonal levels before onset of lay and production traits for individual hens. In the 33.8 C group, after onset of lay, significant positive correlations were observed between serum E2 and egg production and serum LH and egg production; however, these correlation coefficients were not significant in the 37.8 C group. Significant negative correlation coefficients were observed in both groups between serum E2 after onset of lay and age at first egg.

Animals↗
PubMed1984

Effect of dehydration, haemorrhage and oviposition on serum concentrations of vasotocin, mesotocin and prolactin in the chicken.

Serum concentrations of arginine vasotocin (AVT), mesotocin and prolactin were determined by radioimmunoassay in Rhode Island Red chickens during and after dehydration, haemorrhage and oviposition. During dehydration increased circulating levels of AVT, mesotocin and prolactin were found. As water deprivation proceeded, marked differences were observed. After an initial rise in serum AVT, mesotocin and prolactin levels during mild and moderate dehydration, concentrations of both AVT and prolactin tended to normalize during continued water deprivation, while those of mesotocin remained high throughout the whole dehydration experiment with the highest at the end of the water-deprivation period. Removal of 5 ml blood at intervals of 10 min during six consecutive time-periods did not affect serum osmolality and circulating levels of AVT and prolactin, but slightly increased mesotocin. These results suggest an osmoregulatory role for AVT and prolactin, whereas mesotocin may be involved in volume control. Finally, 1 min after oviposition, control values of 19.5 +/- 3.4 pmol AVT/1 (n = 9) were raised more than sevenfold to 142.9 +/- 12.5 pmol/l (n = 11). Thereafter, a decline occurred with a half-life for AVT of 13 min with raised serum levels up to 31 min after oviposition. In contrast, the serum concentrations of mesotocin and prolactin remained unaffected by oviposition.

Animals↗
PubMed1983

The presence of vasotocin and mesotocin in serum and the hypothalamo-neurohypophyseal axis of chick embryos before hatching and in posthatch chicks.

Decreasing hematocrit values were observed in chick embryos, from Day 17 to 1 day posthatching. Arginine vasotocin (AVT) and mesotocin (MT) were determined radioimmunologically in serum, neural lobe, and hypothalamic tissue. Serum levels of AVT and MT were significantly increased on Day 18 of incubation compared to Day 17. Thereafter AVT levels decreased, reaching at hatching levels even below Day 17. Serum MT remained elevated on Day 19, but decreased thereafter to the concentration values of Day 17. The amount of AVT in the preoptic hypothalamus and infundibulum was maximal on Day 19, whereas in the neural lobe the maximum was attained on Day 20. The MT content of the infundibulum and neural lobe reached a maximum plateau on Day 18. These results suggest that a stimulation of the hypothalamo-neurohypophyseal axis in the chick embryo occurs at the end of incubation. A possible causal relation with the observed decreasing hematocrit values is discussed.

Animals↗
PubMed1983

Metabolism and growth of chickens before and after hatch in relation to incubation temperatures.

Chick embryos were incubated at 35.8 C from days 1 to 10 and at 37.8 C from day 11 to hatching. Control embryos were incubated at 37.8 C. Other environmental conditions were standardized. Embryos incubated at 35.8 C showed compensatory growth when compared to embryos of the control group and showed a higher heat production (kJ/embryo/hr) expressed as a linear function of dry embryo weight (g) or incubation time (days). After hatching, the compensatory growth of the chickens incubated at 35.8 C (days 1 to 10) continued, as demonstrated by analyses of the weight of the body, liver, and the gastrointestinal tract. The same animals produced more heat per unit of time and body weight. Adult hens from this group showed a trend for higher heat production per unit body weight as well as a higher dry matter content. These results suggest a link between in ovo environmental conditions, growth processes, and metabolic level up to the reproduction period of domestic fowl.

Animals↗
PubMed1982

Variations of metabolism and feed efficiency in laying R.I.R.-hens in relation to prenatal environmental temperatures.

Starting from an hypothesis concerning the long-term effects of exogenous treatment during the ontogeny of mammals and birds, we incubated Rhode Island Red (RIR) eggs at different prenatal temperatures (table 1) to study the feed efficiency, development, reproduction and energy metabolism of the hens. The maintenance requirement varied (up to 30 p. 100) as well as the feed conversion (up to 28 p. 100), but lower maintenance requirements did not always result in a significantly higher net energy gain nor in a higher feed efficiency above maintenance. Laying RIR hens from eggs incubated at 37.8 degrees C vs those from eggs incubated at 36.8 and 35.8 degrees C (days 1-10) showed a significantly (P less than or equal to 0.05) lower fasting heat production, resulting in lower maintenance requirement and higher energy balance mainly composed of fat energy. This was paralleled by a lower feed conversion rate during growth and reproduction. In fasting conditions, these animals showed a lower oxidative metabolism of fats and proteins.

Animal Feed↗
PubMed1982

[Postinfectious (reactive) arthritis--an important differential diagnosis to juvenile chronic arthritis (JCA) (author's transl)].

Symptoms, laboratory findings and clinical course of 10 pediatric patients suffering from postinfectious arthritis are described. The postinfectious arthritis is caused by an infection with Salmonella, Versina, Brucella or Shigella. The illness results from a preceding enteritis accompanied by fever. It differs from the juvenile chronic arthritis by the more clarified etiology and pathogenesis and particularly by the markedly shorter course, the lack of functional deterioration and by normal X-ray findings of the joint structure. In the parainfectious cases a similar pathogenesis is suggested, but the time relation is not as clear; the arthritis is diagnosed ahead of the enteritis. The human leucocyte antigen HLA-B 27 can frequently (90%) be proven in patients suffering from postinfectious arthritis. This is related to a genetic disposition of this type of arthritis as it can be observed in juvenile spondylitis ankylosans and in Reiter-syndrome, which can be considered as a special type of postinfectious arthritis.

Adolescent↗
PubMed1982

[Rheumatic iridocyclitis in childhood--differentiation on the basis of clinical and immunological parameters (author's transl)].

In approximately 10% of the children suffering from juvenile chronic arthritis (JCA), rheumatic iridocyclitis was also diagnosed. In 90 JCA and iridocyclitis patients we studied relative risk, clinical course and prognosis by means of several clinical and immunological parameters. Antinuclear antibodies (ANA), selective IgA-deficiency, oligoarthritis type of onset of the disease and manifestation of JCA during infancy--predominantly in girls--were quite often accompanied by a pronounced susceptibility to rheumatic iridocyclitis, while seropositivity (RF-positivity) and systemic onset of juvenile chronic arthritis normally rule out rheumatic iridocyclitis. Among HLA-B27-positive boys of school age, the acute course of rheumatic iridocyclitis, which rarely results in serious and lasting complications, is more frequent; in some cases juvenile sacroiliitis or ankylosing spondylitis are evident. The evaluation of the risk factors makes it possible to systematically define subgroups likely to develop chronic iridocyclitis and less susceptible groups of patients, thus facilitating early diagnosis and treatment as well as clinical observation of the development of chronic iridocyclitis.

Adolescent↗
PubMed1982

Posthatch growth and development of a circadian rhythm for thyroid hormones in chicks incubated at different temperatures.

Rhode Island Red eggs were incubated at 33.8 and 376.8 C from day 17 until hatching under a photoperiod of 12L:12D. After hatching, the same light schedule was maintained, and all chicks were raised at 25 +/- 1 C and 50% relative humidity. Infrared lamps were used up to 7 days. Pipping and hatching occurred significantly later in chicks incubated at 33.8 C, and the interval between events was prolonged. Chicks of the 33.8 C group had a lower body weight on day 3 posthatch, but relative growth was accelerated from the 2nd week on, resulting in equal weights on day 36 for males and day 43 for females. Circadian mean serum levels of triiodothyronine (T3) during a 24-hr period (blood sampling every 4 hrs) were positively correlated with relative growth rate in both temperature groups, whereas thyroxine (T4) correlated with weight and age. Body weight of females remained lower from day 9 (33.8 C) and 22 (37.8 C) on. In the 37.8 C group, a significant fit of serum T4 to a sinusoidal curve (observed during a 24-hr cycle) was present for both sexes from day 16 on; this was true from day 32 on in the lower incubation temperature group. The acrophases of this rhythm occurred at about 0500 hr (1100 hr after onset of the dark period) and did not differ between temperature groups of sexes. A significant fit to a sinusoidal curve for the T3 data was only possible for both sexes and temperature groups on days 112 and 128 with an acrophase at about 1700 hr. Differences in growth rate between temperature groups can be related to differences in mean serum levels of T3. Differences in growth rate between sexes were not parallelled by differences in levels of thyroid hormones or acrophases, but males did not have a higher amplitude in the sinusoidal T4 rhythm compared to females. This difference was more pronounced in the 37.8 C group.

Animals↗
PubMed1982

Effect of blocking T4-monodeiodination on hatching in chickens.

Chick embryos were injected with iopanoic acid (IOP) on either day 17 or 18 of incubation, and radioimmunoassays of triiodothyronine (T3) and thyroxine (T4) in serum and thyroid glands were performed from day 19 on through pipping and hatching and 1 day after hatching. The IOP was able to block T4 to T3 conversion in chick embryos from day 19 of incubation. Blocking T4 conversion did not delay hatching significantly, nor did it affect embryonic mortality significantly. Yolk sac retraction was not affected at hatching. A rise in serum reverse T3 (rT3) and T4 was observed after IOP administration. The rise in T4 could not be explained solely by a decreased T4 conversion. The results indicated that peripheral monodeiodination occurs in the late chick embryo.

Animals↗
PubMed1981

[Amyloidosis-a dreaded complication of juvenile chronic arthritis (JCA). (author's transl)].

Our studies describe symptoms, clinical course and prognosis of 60 children (out of a total of 2063 patients) suffering from chronic arthritis complicated with amyloidosis. Amyloidosis is predominantly caused by the systemic subgroup of juvenile chronic arthritis, which is characterized by high inflammation activity. The amyloidosis and the sequelae are one of the main causes of death in JCA (27 of the 90 lethal cases in our juvenile chronic arthritis unit were connected with amyloidosis). Proteinuria is the most frequent sign in the early stage of the amyloidosis. Early diagnose and treatment by cytostatic drugs like chlorambucil seems to improve the prognosis. The cumulative survival results in the existence of two different subgroup of amyloidosis.

Adolescent↗
PubMed1981

[Effect of the length of egg storage on duration of incubation and serum thyroid hormone levels in the chick embryo].

After storage at 12 degrees C and 90 to 95 p. 100 humidity, for periods of 1, 5, 8, 11 and 14 days, Rhode Island Red eggs were incubated at 37.5 degrees C and 60 p. 100 humidity. Whatever the total duration of incubation within the experimental conditions, maximal serum levels of triiodothyronine (T3) and thyroxine (T4) were obtained the day of pipping. Embryos having perforated the air-space membrane the day before pipping showed elevated serum T3, but not T4, levels as compared to embryos without a perforation. The lower serum T3 levels, obtained at pipping, after longer periods of preincubation storage are discussed in relation to other experiments on perinatal changes in serum iodo-hormones.

Animals↗