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Biomedical subjects

F Müller

Publications and source records attributed to F Müller.

At least 379 records · Page 21Linked to original sources
PubMed1986

Chemical modification of tyrosine residues in p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens: assignment in sequence and catalytic involvement.

p-Hydroxybenzoate hydroxylase was modified by diethyl pyrocarbonate at pH values greater than 7 and by p-diazobenzoate. Modification of the enzyme by diethyl pyrocarbonate abolishes the affinity of the enzyme for the substrate p-hydroxybenzoate. Modification by p-diazobenzoate has the same effect on the enzyme. The enzyme is protected against these modifications by the effector p-fluorobenzoate. The data indicate that the modification of one tyrosine residue in the active center of the enzyme is responsible for the loss of enzyme activity. This tyrosine residue has been identified by sequence studies using radioactively labeled p-diazobenzoate and was found to be most probably Tyr-222. Diethyl pyrocarbonate reacts with a tyrosine residue in the active center other than Tyr-222; the former could not be identified. Sequence studies further showed that Cys-211 is also partially modified by p-diazobenzoate. In addition, the sequence of residues 343-345 was found to be Ser-Trp-Trp instead of the tentative assignment Ser-Tyr-Trp made earlier. The results are briefly discussed on the basis of the existing three-dimensional model of the enzyme.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed1986

Somitic-vertebral correlation and vertebral levels in the human embryo.

Somitic and vertebral interrelationships and levels were studied in 84 human embryos of stages 9-23 (3-8 postovulatory weeks). The first four somites are occipital, the occipitocervical junction is at somites 4/5, and eight somites are involved in the cervical region: X, Y, Z, and C. 3-7. By stage 17 the total number of occipitovertebral "units," namely 38 or 39, is attained. Resegmentation (Neugliederung) of sclerotomes is not supported. A new scheme of somitic/vertebral correlation is proposed in which somites and centra are in register. Differential growth of the regions of the vertebral column was calculated, and it was found that the percentages of the total column occupied by the various regions vary from one stage to another. The cervical and coccygeal regions decrease, the thoracic and lumbar regions increase, and the sacral region remains more or less constant during embryonic development. The following structures descend with reference to the vertebral column during the embryonic period proper: roots of lower limbs, thyroid gland and thymus, tracheal bifurcation, lungs, heart, diaphragm, abdominal arteries, mesonephroi, and suprarenal glands. The gonads may descend slightly. The scapulae and the separation point between the trachea and the esophagus remain at a fairly constant level. The metanephroi ascend. The migration of many of these structures (e.g., the heart, diaphragm, and metanephroi) is much more marked in the embryonic period than later although it continues during the fetal and postnatal periods. The conus medullaris ascends during the fetal period. Anomalies of migration that affect such organs as the thyroid gland, gonads, and metanephroi are discussed.

Embryo, Mammalian↗
PubMed1986

Tensile properties of human knee joint cartilage: I. Influence of ionic conditions, weight bearing, and fibrillation on the tensile modulus.

The flow-independent (intrinsic) tensile modulus of the extracellular matrix of human knee joint cartilage has been measured for normal, fibrillated, and osteoarthritic (removed from total knee joint replacements) cartilage. The modulus was determined in our isometric tensile apparatus and measured at equilibrium. We found a linear equilibrium stress-strain behavior up to approximately 15% strain. The modulus was measured for tissues from the high and low weight-bearing areas of the joint surfaces, the medial femoral condyle and lateral patello femoral groove, and from different zones (surface, subsurface, middle, and middle-deep) within the tissue. For all specimens, the intrinsic tensile modulus was always less than 30 MPa. Tissues from low weight-bearing areas (LWA) are stiffer than those from high weight-bearing areas (HWA). The tensile modulus of the ECM correlates strongly with the collagen/proteoglycan ratio; it is higher for LWA than for HWA. Osteoarthritic cartilage from total knee replacement procedures has a tensile stiffness less than 2 MPa.

Adult↗
PubMed1986

The development of the human brain and the closure of the rostral neuropore at stage 11.

Twenty embryos of stage 11 (24 days) were studied in detail and graphic reconstructions of twelve of them were prepared. The characteristic feature of this stage is 13-20 pairs of somites. The notochord sensu stricto appears first during this stage, and its rostral and caudal parts differ in origin. Rostrally, the notochordal plate is being transformed into the notochord in a caudorostral direction. The caudal part, however, arises from the axial condensation in the caudal eminence in a rostrocaudal direction. The caudal eminence (or end bud) represents the former primitive streak. The somites are increasing in number at a mean rate of 6.6 h per pair. The rostral neuropore closes towards the end of stage 11. The closure is basically bidirectional, being more rapid in the roof region and producing the embryonic lamina terminalis and future commissural plate in the basal region. The caudal neuropore is constantly open. The brain comprises telencephalon medium (represented by the embryonic lamina terminalis) and a series of neuromeres: 2 for the forebrain (D1 and D2), 1 for the midbrain, and 6-7 for the hindbrain (RhA-C; RhD is not clearly delineated). The forebrain still occupies a small proportion of the total brain, whereas the spinal part of the neural tube is lengthening rapidly. Some occlusion of the lumen of the neural tube was noted in 4 embryos, all of which had an open rostral neuropore. Hence there is at present no evidence that occlusion plays a role in expansion of the human brain. The marginal (primordial plexiform) layer is appearing, particularly in rhombomere D and in the spinal portion of the neural tube. The neural crest is still forming from both the (open) neural groove and the (closed) neural tube, and exclusively from both neural (including optic) and (mainly) otic ectoderm. The optic sulcus is now prominent, and its wall becomes transformed into the optic vesicle towards the end of stage 11. At this time also, an optic sheath derived from mesencephalic crest and optic crest is present. The mitotic figures of the optic neural crest are exceptional in being situated in the external part of the neural epithelium. The otic pit is becoming deeper, and its wall is giving rise to neural crest that is partly added to the faciovestibulocochlear ganglion and partly forms an otic sheath. The nasal plate does not yet give off neural crest.

Brain↗
PubMed1986

Studies on the substrate specificity of alpha- and beta-amylase of Entamoeba histolytica.

From the supernatant fraction of cell homogenates of Entamoeba histolytica alpha-amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) and beta-amylase (1,4-alpha-D-glucan maltohydrolase, EC 3.2.1.2) were separated and purified by gel filtration and isoelectric focusing, followed by DEAE- and CM-chromatography, respectively. Both enzymes catalyzed the degradation of amylose, amylopectin and glycogen. Hydrolysis of polysaccharides by alpha-amylase yielded as reaction products maltose, maltotriose, maltopentaose and maltohexaose, but no free glucose. beta-Amylase produced as main degradation product of glucopolysaccharides maltose and to a minor extend maltotriose, but no glucose. alpha- and beta-amylase were able to hydrolyze 4-nitrophenyl-alpha-D-glucooligosaccharides (Gn-pNP) containing more than two glucose units per molecule. Under identical conditions G6-pNP was cleaved at highest velocity by alpha-amylase, while beta-amylase exhibited the highest activity with G4-pNP as substrate. alpha-Amylase hydrolyzed G4-pNP, G5-pNP and G6-pNP yielding as main reaction product G2-pNP, but also the formation of G1-pNP and G3-pNP from G4-pNP, of G1-pNP, G3-pNP and G4-pNP from G5-pNP, of G1-pNP, G3-pNP, G4-pNP and G5-pNP from G6-pNP was observed. alpha-Amylase as endo-glucohydrolase attacked all glycosidic bonds in G6-pNP, G5-pNP and G4-pNP, while beta-amylase successively removed maltose units from the non-reducing ends of the glycosides.

Amylases↗
PubMed1986

[Prevalence and etiology of mental problems in tumor patients].

Data obtained from a questionnaire completed by 177 cancer patients were analyzed for prevalence of depressive and anxiety disorders and aspects of coping behavior. We found a high correlation between frequency of depressive symptoms and the period time after which cancer was diagnosed. According to data reported by other authors, prevalence of depression ranged between 21% and 32%. Anxiety disorders were found in about 40% of all cancer patients. Chemotherapy seems to be very stressing: During the course of therapy, we found a duplication of depressive symptoms, severe depression increases from 0% to 17%. Personality-traits possibly predict anticipated nausea and vomiting (ANV). Patients with ANV show higher values in depression, anxiety, fatalism, but lower ones in internal control measured before chemotherapy.

Adaptation, Psychological↗
PubMed1986

Assay for thyroid growth stimulating immunoglobulins: stimulation of [3H]thymidine incorporation into isolated thyroid follicles by TSH, EGF, and immunoglobulins from goitrous patients in an iodine-deficient region.

Estimations were carried out of [3H]thymidine incorporation during culture of isolated porcine thyroid follicles in the presence of standard TSH or epidermal growth factor (EGF) both alone and together with anti-TSH or anti-EGF serum, and of immunoglobulins fractionated from the sera of patients from our endemic goitre area with iodine deficiency. A significant stimulation of thymidine incorporation was exerted by TSH when thyroglobulin was present in the culture medium, and also by EGF. TSH stimulation was abolished by anti-TSH serum, in contrast to the effect of EGF. Anti-EGF serum, on the other hand, blocked the effect of EGF, but not that of TSH. The sera of 20 out of 72 patients (27%) with euthyroid goitre (not operated on) and of ten out of 26 patients (38%) with recurrent euthyroid goitre contained immunoglobulins stimulating thyroid growth (TGI). There was no correlation of TGI with other thyroid antibodies. TGI have to be regarded as a pathogenetic factor of euthyroid goitre also in patients from an endemic region especially in recurrent cases.

Animals↗
PubMed1986

Effect of diabetes and adrenocortical state on intestinal transport capacity and (Na+ + K+)-activated adenosine triphosphatase activity.

(Na+ + K+)-activated adenosine triphosphatase activity in the mucosal homogenate of rat small intestine estimated under conditions of experimental diabetes, application of corticosteroids, adrenalectomy or inhibition of adrenocortical function suggests a general parallelism between the capacity for monosaccharide absorption and enzyme activity. Studying the kinetic parameters it has been found that the maximal velocities of monosaccharide uptake as well as of (Na+ + K+)-activated adenosine triphosphatase reaction are significantly different, whereas sugar concentrations for halfmaximal transport velocities and enzyme-substrate affinity constants remain unaltered. From studies with purified brush borders and basolateral plasma membranes it has been shown that the activity changes were caused exclusively by that part of (Na+ + K+)-activated adenosine triphosphatase which is localized in the basolateral plasma membranes. The enzyme activity in the brush border region remains unchanged. These findings support a concept of intestinal transport mechanism which suggests that the basolateral part of (Na+ + K+)-activated adenosine triphosphatase is responsible for metabolic energy supply.

Adrenal Cortex Hormones↗
PubMed1986

[Atlas of the stages of development of the external forms of the brain in the human embryo].

The various external features of the developing human brain during the embryonic period proper (up to 8 postovulatory weeks) are illustrated as they appear in reconstructions made from embryos of Carnegie stages 8 to 23. This is the first systematic, stage-by-stage account. The appearances are compared with those that can be seen in intact embryos of corresponding stages up to 7 postovulatory weeks. The brain of an early fetus (9 postovulatory weeks) is also included. The medial views will be treated in a subsequent article.

Atlases as Topic↗
PubMed1986

Specific immunoglobulin M and G antibodies in the rapid diagnosis of human treponemal infections.

The serological response to treponemal infections in men before and after specific treatment is analyzed. From the described observations several consequences and possibilities for a specific immunological diagnosis are discussed. In particular, it is shown that early diagnosis of syphilis in need of treatment can be achieved by demonstration of T pallidum-specific IgM antibodies. Finally, new insights into the role of antibody correlations between serum and cerebrospinal fluid are mentioned that have established the detection of asymptomatic neurosyphilis.

Antibodies, Bacterial↗
PubMed1986

Renin relationship to sex, race and age in a normotensive population.

The relationship of renin activity to sex, race (black or white) and age (less than 50 or greater than or equal to 50 years of age) was examined in 236 normal subjects measure yearly for up to 9 years. There were 58 white women (34 less than 50 years, 24 greater than or equal 50 years), 66 white men (30 less than 50 years, 36 greater than or equal to 50 years), 57 black women (34 less than 50 years, 23 greater than or equal to 50 years) and 55 black men (34 less than 50 years, 21 greater than or equal to 50 years). The results showed men had higher mean renin activities than women, whites had higher activities than blacks and those of under 50 years had higher activities than those of over 50 years. However, the sex and race differences primarily occurred as a consequence of a lack of decline in renin activity with age among white men. The relationship with age as a continuous variable was weak (r = -0.21) and no relationship with age was found in 22 subjects with a least 7 years of data. No significant differences in urinary sodium excretion were observed between the groups. These results suggest that renin activity tends to be lower in older subjects and that differences in renin activity related to sex and race, while statistically significant, may not be physiologically important.

Age Factors↗
PubMed1986

The early origin of vertebral anomalies, as illustrated by a 'butterfly vertebra'.

An anomalous (butterfly) eleventh thoracic vertebra in a fetus of 63 mm greatest length is described and graphic reconstructions (together with normal controls) are provided. The cartilaginous hemicentra are separated by disc-like material. Cartilaginous bars to adjacent vertebrae are present. The neural arch is complete. The notochord is not duplicated. Only one comparable case in the embryonic period has been described previously. After a discussion of cleft vertebrae in the human and in experimental animals, a developmental timetable of the appearance of several vertebral anomalies is provided. The sensitive period for butterfly vertebrae, depending on the mode of origin, seems to be 3-6 postovulatory weeks. More severe anomalies, such as the split notochord syndrome, appear earlier. It is concluded that most of the vertebral anomalies discussed arise during the embryonic period proper, although the timing of a few, such as spina bifida occulta, extends into the early fetal period.

Arteries↗
PubMed1986

The meninges in human development.

The brain and cranial meninges were studied in 61 serially sectioned embryos of stages 8-23. Much earlier stages than those examined by previous authors provided a more comprehensive view of meningeal development. As a result, the possible and probable sources of the cranial and spinal meninges are believed to be: (a) prechordal plate, (b) unsegmented paraxial (parachordal) mesoderm, (c) segmented paraxial (somitic) mesoderm, (d) mesectoderm (neural crest), (e) neurilemmal cells (neural crest), and (f) neural tube. Some of these sources (a, b, d) pertain to the cranial meninges, others (c, d, e) to the spinal coverings. The first of the future dural processes to develop is the tentorium cerebelli, which, at the end of the embryonic period proper, differs considerably in shape and composition from the later fetal and postnatal tentorium. The embryonic dural limiting layer (Duragrenzschicht) probably corresponds to the interface layer of the adult meninges. The appropriate literature was reviewed and summarized.

Arachnoid↗
PubMed1985

Intra-blood-brain-barrier synthesis of HTLV-III-specific IgG in patients with neurologic symptoms associated with AIDS or AIDS-related complex.

Intra-blood-brain-barrier production of virus-specific antibody is good evidence of infection within the blood-brain barrier. Patients with the acquired immuno-deficiency syndrome (AIDS) have an increased incidence of neurologic abnormalities--i.e., unexplained, diffuse encephalopathy manifested clinically as chronic progressive dementia. To define the role of human T-cell lymphotropic virus Type III (HTLV-III), the etiologic agent of AIDS, in the pathogenesis of neurologic dysfunction, we compared cerebrospinal fluid and serum from patients with neurologic symptoms associated with AIDS and the AIDS-related complex for the presence of antibodies directed against HTLV-III. Antibodies directed against HTLV-III antigens were detected by four immunologic tests: a fixed-cell immunofluorescence assay, an enzyme-linked immunosorbent assay, immunoblots of viral lysates, and immunoprecipitation of cellular lysates. All patients were seropositive, and 22 of 23 (96 per cent) had HTLV-III-specific antibodies in their cerebrospinal fluid. Unique oligoclonal IgG bands were detected in the cerebrospinal fluid, and the rate of IgG synthesis within the blood-brain barrier was elevated. In eight of nine patients tested, the enzyme-linked immunosorbent assay showed that the percentage of HTLV-III-specific IgG in cerebrospinal fluid was higher than in serum, suggesting that HTLV-III infection of neurologic tissue occurs in the majority of patients with neurologic disease associated with AIDS or its related complex.

Acquired Immunodeficiency Syndrome↗