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H Dirks

Publications and source records attributed to H Dirks.

9 recordsLinked to original sources
PubMed1990

Localization of phosphoserine residues in the alpha subunit of rabbit skeletal muscle phosphorylase kinase.

The alpha subunit of skeletal muscle phosphorylase kinase, as isolated, carries phosphate at the serine residues 1018, 1020 and 1023. Employing the S-ethyl-cysteine method, these residues are found to be phosphorylated partially, i.e. differently phosphorylated species exist in muscle. Serine 1018 is a site which can be phosphorylated by the cyclic-AMP-dependent protein kinase. The serine residues 972, 985 and 1007 are phosphorylated by phosphorylase kinase itself when its activity is stimulated by micromolar concentrations of Ca2+. These phosphorylation sites are not identical to those found to be phosphorylated already in the enzyme as prepared from freshly excised muscle. A 'multiphosphorylation loop' uniquely present in this but not in the homologous beta subunit contains all the phosphoserine residues so far identified in the alpha subunit.

Amino Acid Sequence↗
PubMed1981

[Diagnostic problems of hyperthyroidism in the older age group (author's transl)].

Seventy-seven patients aged more than 60 years from the iodine deficiency area of southern Lower Saxony with hyperthyroidism, diagnosed by assessment of thyroid parameters, showed a nonspecific disease picture with surprising frequency when compared with younger patients. Predominant characteristics were weight loss (86%), general weakness (78%), tachycardia (74%), reduced appetite (66%), exertional dyspnoea (60%), apathy, lack of initiative or depression (48%), and uncharacteristic abdominal complaints (20%). A goitre was not palpable in 30 patients (39%). Laboratory diagnosis was hampered by relative or absolute TBG deficiency and conversion inhibition in the form of a low-T3 syndrome as evidence of non-thyroidal changes in generalised disorders. Neither thyroxine nor triiodothyronine were increased in ten patients (13%). Only by additional routine estimation of the thyroxine-binding index (T3 in vitro test) as indicator of free binding capacity could the diagnosis be ascertained in these cases. The poor prognosis be ascertained in these cases. The poor prognosis of hyperthyroidism in the older age group necessitates generous use of specific diagnostic laboratory investigations in cases with suspicious symptoms.

Age Factors↗
PubMed1977

Metabolic and clinical studies on patients with acromegaly treated with bromocriptine over 22 months.

In twenty-two patients with active acromegaly who were untreated or unsuccessfully operated or irradiated (mean growth hormone (GH) values greater than 4 ng/ml) the following investigations were performed: routine laboratory tests, tomography of pituitary fossa, oral glucose tolerance tests, TRH and other pituitary function tests and GH profiles over 5-10 h before and during bromocriptine treatment with daily doses between 7.5 and 50 mg. In seventeen patients GH was suppressed to less than 50% by bromocriptine, in thirteen of them it was normalized on at least one occasion. A TRH induced GH release was observed in all but two responders to bromocriptine before therapy. This effect of TRH was not blunted during treatment with bromocriptine and also in the two patients with negative tests before therapy a significant GH increase was observed. In no non-responder to bromocriptine was a significant increase of GH after TRH observed. One patient showed a secondary resistance to bromocriptine during a period of treatment with griseofulvin. In the remaining sixteen patients the GH suppression has been consistent for between 3 and 22 months. A single dose of pimozide abolished the bromocriptine effect on GH totally in one patient; in others a slight or no significant effect was observed. Tissue swelling and sweating decreased in all bromocriptine responders and glucose tolerance improved in five patients. In four diabetic patients a partial or full remission of diabetes occurred. Apart from postural hypotension after the first administration in two patients no other severe side effects have been observed. Sella size and the other pituitary functions did not change during the time of the study. It seems that a high percentage of acromegalics may be successfully treated with bromocriptine.

Acromegaly↗
PubMed1975

[Therapy of acromegaly using bromocriptine].

Oral administration of 1.0 or 2.5 mg bromocriptine (CB 154: 2-brom-alpha-ergocryptine) in nine of twelve patients with active acromegaly resulted in a reduction of growth hormone level by 80-90% over 8-10 hours. During treatment for 2-9 months with daily doses of 4.0 to 10.0 mg bromocriptine, there was a sustained reduction of growth hormone levels in these patients. At the same time soft-tissue swellings and tendency towards sweating decreased. In two patients with diabetes mellitus the blood sugar profile improved and in one of them the insulin dose could be markedly reduced. The rise in growth hormone levels after TRH administration also occurred during bromocriptine treatment. In those patients in whom growth hormone levels failed to react to either acute or chronic administration of bromocriptine no rise followed TRH administration. It is possible that in these patients there is a hypophyseal adenoma without hypothalamic control. On gradually increasing dosage bromocriptine was tolerated without side effects.

Acromegaly↗