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H Hofmann

Publications and source records attributed to H Hofmann.

At least 145 records · Page 8Linked to original sources
PubMed1986

[Effect of normoglycemic metabolic status in pregnancy on the course of diabetic retinopathy].

Seventy-nine pregnant diabetic women were put under intensified obstetric observation during pregnancy with the aim of achieving normoglycemia. The prevalence and development of diabetic retinopathy were evaluated in 28 of these diabetic women and compared with a control group of 26 diabetic men. The present paper communicates the fundus changes, classified according to the stages of diabetic retinopathy, and their development in the two groups.

Blood Glucose↗
PubMed1986

Epidemiological analysis of Neisseria gonorrhoeae in the Federal Republic of Germany by auxotyping and serological classification using monoclonal antibodies.

We evaluated a new serological classification system for Neisseria gonorrhoeae based on monoclonal antibodies directed against epitopes on the outer membrane protein I, in conjunction with auxotyping, to analyse gonococci from two cities in the Federal Republic of Germany. Isolates of N gonorrhoeae were collected during 1976-8 and 1980-2 in Lübeck, and during 1980-2 in Heidelberg. Between the two study periods in Lübeck, we observed an appreciable decrease in strains of the auxotype that requires arginine, hypoxanthine, and uracil (AHU-) and with serovar class PrIA-1 and the emergence of strains with the proline requiring auxotype and PrIB-1 serovar class. Serovar PrIA-1 accounted for 89 (97%) of 92 strains with the AHU- auxotype as opposed to 12 (4%) of 297 strains with other auxotypes (p less than 0.0001). Disseminated gonococcal infection was associated with AHU-/PrIA-1 strains. Penicillinase producing N gonorrhoeae (PPNG) strains belonged to eight different auxotype and serovar classes, which indicated that different strains had been imported. Classification of strains of N gonorrhoeae by auxotype and serovar class permits analysis of temporal changes in gonococcal populations, and of migrations of gonococci between different geographical areas. Typing N gonorrhoeae, together with assessing antibiotic susceptibilities, may prove useful for further studies of the epidemiology and control of gonorrhoea.

Antibodies, Monoclonal↗
PubMed1986

[Detection of herpes simplex virus antigen with an enzyme immunoassay and direct immunofluorescence].

A total of 464 clinical specimens from patients with extragenital and genital lesions and from the cervix of asymptomatic women were examined for the presence of Herpes-simplex-virus antigen by using a commercially available enzyme immunoassay Kit (ELISA, Dakopatts) and a direct immunofluorescence technique with monoclonal antibodies (Syva-Merck). The detection rate was compared to the isolation rate of the tissue-culture technique. In extragenital lesions the sensitivity of the ELISA technique and immunofluorescence was determined to be 78.9% and 80% and in genital lesions 46.2%. In cervical clinical specimens, the sensitivity of both techniques was determined to be 5.7% and 15.4%. An HSV infection, negative in tissue culture, was diagnosed in 22 and 27 cases, respectively, using ELISA and immunofluorescence. This diagnosis was confirmed in 21 and 22 cases by the other immunological technique. For this reason, it can be assumed that in some cases direct immunological techniques can be more sensitive than the tissue culture technique. With regard to asymptomatic and manifest infections, reliable results are only obtainable in cases of manifest disease with blisters or scabs.

Antibodies, Monoclonal↗
PubMed1986

[Detection of Chlamydia trachomatis antigen with an enzyme immunoassay].

Urogenital swabs (571) were investigated with a solid-phase enzyme immunoassay for the detection of Chlamydia trachomatis antigen (Chlamydiazyme, Abbott). The results were compared with the conventional cell culture method (McCoy cell culture). Urogenital C. trachomatis infections were diagnosed with the cell culture in 14 of 122 male STD patients (12%), in 12 of 79 female STD patients (15%), in 23 of 89 prostitutes (26%), and in 3 of 115 asymptomatic males (3%). In comparison with cell culture, the sensitivity of Chlamydiazyme for urethral specimens from male STD patients was 86%. In female STD patients, for urethral specimens a sensitivity of 83% was found and for cervical specimens a sensitivity of 80%. The corresponding values for specimens from prostitutes were 60% and 100%, respectively. The specificity of Chlamydiazyme for urethral specimens of male STD patients reached 95%. With respect to urethral and cervical specimens of female STD patients, the specificity was 88% and 82%, respectively, and in prostitutes 92% each. The low specificity in female patients cannot be ascribed only to Chlamydiazyme since, after subcultivation and detection of inclusions by the use of fluorescein-labeled monoclonal antibodies, some of the false-positive Chlamydiazyme results turned out culture positive. This means that the specificity of Chlamydiazyme is actually higher. Because it can be performed rapidly and simply and reaches detection rates approaching those of the cell culture method, the enzyme immunoassay is an improvement in the diagnosis of C. trachomatis infections.

Adult↗
PubMed1985

Structural model of the collagen-like region of C1q comprising the kink region and the fibre-like packing of the six triple helices.

A detailed three-dimensional model of the collagenous part of C1q was derived by model building and computer-aided energy refinement calculations. The proposed structure is based on the collagen-like (-Gly-Xaa-Yaa-) repeating sequence of 78 to 81 residues in the N-terminal regions of the constituent A, B and C chains, on the mode of disulphide linkage between the 18 chains of C1q, and on its electron microscopically derived gross structure. It is demonstrated that the interruptions of the repeating sequence about half-way along the length of the collagenous regions (Gly36-Ile37-Arg38-Thr39 in the A chain and Ala36-Ile37-Hy138 in the C chain) do not lead to a disruption of the triple helical conformation but rather to a bend of about 60 degrees in an otherwise continuous triple helix. These features are consistent with a flexibility comparable with that of regular triple helices and with the observed low proteolytic susceptibility of the kink region. The azimuthal orientation of the kink is defined approximately by ArgA38 being located in the cap of the knee. Because of this extra residue between two glycine residues, a bad contact that would arise between the methyl group of AlaC36 and the peptide carbonyl of IleA37 in a straight triple helix is relaxed. The model features also a cluster of hydrophobic contacts between large hydrophobic side-chains in the interaction edges between the six collagen triple helices aligned with their about 10 nm long N-terminal regions in the fibril-like endpiece of C1q. The azimuthal orientations of the triple helices were derived by energy calculations of side-chain interactions previously applied to fibre-forming collagens. Independently, the same orientations and interaction edges were derived from the azimuthal orientation of the kink and the electron microscopically observed orientations of the triple helical arms that emerge from the endpiece, and which carry the C-terminal globular binding domains. The structural model has a number of implications for the assembly of the first component of complement from C1q and the zymogen complex C1r2C1s2 and possible mechanisms of its activation.

Amino Acid Sequence↗
PubMed1985

Calcium blocks selectively the EOG-light peak.

The light peak (LP) is a slow increase in the standing potential of the eye and has been attributed to a depolarization of the basal membrane of the retinal pigment epithelium (RPE). We tested effects of different external calcium ion concentrations ([Ca++]0) on the LP in the arterially perfused cat eye. An increase in Ca++ activity by 3.2 mM depressed the LP by 85-90% of its amplitude under control conditions. In contrast the other components of the light response (c-wave, fast oscillation, and second c-wave) did not change. The small increase in [Ca++]0 had insignificant effects on the amplitude-intensity plots of the a- and b-waves of the electroretinogram. Elevated [Ca++]0 had its effect only during onset of light and not after the LP was once initiated. The effects were reversible. Since there is a very high [Ca++] concentration in the RPE cells and the pigment granulas may release Ca++ during illumination (Hess 1975), our results suggest that this ion plays a role during the initiation of the LP.

Animals↗
PubMed1985

Correlation between structure and pathogenicity of potato spindle tuber viroid (PSTV).

Sequence analysis by primer-extension at the level of their cDNA showed that the RNA genomes of various field isolates of potato spindle tuber viroid (PSTV) of different virulence differ from each other only in a few nucleotides in two distinct regions of the rod-shaped molecule. Despite insertions and deletions the chain length of 359 nucleotides is strictly conserved in all the isolates studied. Thermodynamic calculations revealed that due to the observed sequence differences the region located at the left hand part of the rod-like secondary structure of the PSTV molecule, denoted 'virulence modulating (VM) region', becomes increasingly unstable with the increasing virulence of the corresponding isolate. Based on these data we propose in molecular terms a model for the mechanism of viroid pathogenicity. It implies that the nucleotides of the VM region specify and modulate the binding- and hence the competition-potential of the PSTV RNA molecule for a still unknown host factor(s) and thus determine the virulence of PSTV.

Base Sequence↗
PubMed1985

The electroretinogram, standing potential, and light peak of the perfused cat eye during acid-base changes.

DC recordings of light-evoked responses were made in the isolated, arterially perfused cat eye during four acid-base changes designed to alter intracellular pH (pHi) without appreciably altering extracellular pH (pH0). Two acid-base changes were designed to decrease pHi: substitution of high pCO2, high [HCO3-] perfusate for control perfusate and injection of NaHCO3 solution (pH 7.4) into the control perfusate. The initial effects of these two changes were similar: standing potential decreased, the b-wave amplitude decreased, and the c-wave amplitude increased. Subsequent effects, which included rebounds, were complex. The two other acid-base changes were designed to increase pHi: substitution of low pCO2, low [HCO3-] perfusate for the control perfusate and injection of NH4Cl solution into the control perfusate. The initial effects of these two changes were similar; the effects were opposite to those described above for acid-base changes (i) and (ii). The effects of all four acid-base changes were reversible. From these and previously published findings on the effects of pH0, we conclude that during acid-base changes, the initial change in the standing potential varies directly with pHi/pH0, the initial change in b-wave amplitude varies directly with pHi, and the initial change in c-wave amplitude varies inversely with pHi. We also studied the effects of the four acid-base changes on the light peak, a slow voltage response to light generated by the retinal pigment epithelium. Under acid-base changes (i), (ii), and (iii) the light peak was severely depressed. Injection of 2 mM NH4Cl, acid-base change (iv), had little effect on the light peak; however, injection of 5-10 mM NH4Cl did depress the light peak. These results may be interpreted in several ways, for example, the light peak may be sensitive to changes in [HCO-3]0 or to pHi. In any case, we conclude that pH0 is a relatively minor factor influencing the amplitude of the light peak.

Acid-Base Equilibrium↗
PubMed1985

Tick-borne encephalitis: a simple method for detection of antibody production in the brain.

Antibodies found in c.s.f. of patients with TBE are usually produced in the CNS itself, although their presence might also be due to a leak in the blood brain barrier. In the case of local antibody production the ratio of the TBE specific IgM or IgG to the total immunoglobulin is relatively high in c.s.f., whereas in case of a leak this ratio is lower and corresponds to that of the serum. Local antibody production in the brain can therefore be assumed, if the ratio is higher in c.s.f. than in serum. It is possible to determine this ratio in an anti-mu or anti-gamma capturing antibody ELISA, provided that the concentration of capturing antibodies represents the limiting factor of the test system. Under these conditions the absorbance values obtained are a direct reflection of the TBE reactive to nonreactive antibody ratio, since they compet for the limited binding sites presented on the solid phase. Higher extinction values of c.s.f. compared to that of serum are therefore an indication for local antibody production in the brain. Using the method described, differences were found in the production of IgM and IgG antibodies against TBE in the CNS from patients with different clinical history.

Antibodies, Viral↗