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Biomedical subjects

J Sachs

Publications and source records attributed to J Sachs.

At least 37 records · Page 2Linked to original sources
PubMed1990

Major histocompatibility complex (MHC) protein analysis by optimised two-dimensional electrophoretic methods.

Human histocompatibility molecules HLA-Class I and Class II (DR, DQ, DP) were analysed using three two-dimensional protocols: nonequilibrium pH gradient electrophoresis (NEPHGE), isoelectric focusing-acidic gradient (IEF-AG) and isoelectric focusing-basic gradient (IEF-BG). The three methods differ in their carrier ampholyte combinations and electrophoretic conditions. They provide different pH gradients and therefore different electrofocusing profiles. The NEPHGE protocol was adequate for separating proteins across a broad range of pI mobilities, i.e. 4.4 pH units between the acidic and the basic end. In contrast, the IEF-AG and the IEF-BG protocols gave a separation power across a narrow pH range, 1.9 and 1.7 pH units respectively. Thus, whereas the NEPHGE protocol provides a tool for a global major histocompatibility complex (MHC) antigen profile analysis, the IEF-AG and -BG allows one to investigate subcomponents of the individual MHC chains. For example, NEPHGE analysis of the HLA Class I heavy chain revealed a single spot. However, IEF-BG revealed the presence of six equidistantly spaced spots spanning a short pH gradient with identical molecular weight. Similar improved resolution was seen for the HLA-DR, DQ, and DP molecules. The IEF acidic gradient was adequate for separating the alpha chain; the IEF basic gradient gave better resolution of the beta chains. This data provides a baseline set of conditions for both analytical and preparative MHC protein studies prior to amino acid sequencing.

Alleles↗
PubMed1990

GDA-J/F3 monoclonal antibody as a novel probe for the human sperm tail fibrous sheath and its anomalies.

GDA-J/F3 monoclonal antibody (MoAb) recognized an antigen in the fibrous sheath (FS) of human spermatozoa. This was based on: (i) intracellular localization of the antigen which was limited to the principal piece of the sperm tail; (ii) its absence from the cilia of trachea and nasal mucosa which lack FS; (iii) immunogold electron microscopy (IEM) which confirmed its ultrastructural localization to the FS. The antibody was used for the detection of abnormal germ cells in human semen. Nucleated cells other than spermatozoa (NCOS) obtained from oligozoospermic donors were screened with GDA-J/F3 MoAb using the indirect immunofluorescence test. The antibody which stains only the tails in normal cells, produced diffuse cytoplasmic immunofluorescence inside some spermatids. Using phase contrast microscopy, the tails in these spermatids were either present or undetectable. Electron microscopy studies of the NCOS showed the lack of the FS in those which had the tails (afibrous tail), or the presence of disorganized tails (tail dysgenesis) in the others. This antibody therefore provides a useful analytical tool for probing the FS as well as for the easy identification of certain abnormal germ cells in human semen.

Antibodies, Monoclonal↗
PubMed1990

Association of DR4 related RFLP bands and RA in Greeks.

Using the Taq1 restriction enzyme and DR beta, DQ alpha probes, the DNAs of Greek RA patients and controls were characterised for RFLP's associated with DR4. Three DR beta bands, 14.8kb, 6.1kb and 5.4kb were observed at significantly higher frequency in the patients compared with controls. By using a DQ alpha probe, the 2.6kb band (associated with DR1, DRw10, DRBR and DRw14 (Dw9)) was at a significantly raised frequency in the patients. The DQ alpha 5.3kb band associated with DR4, DR7 and DR9 was also raised in the RA patients although this increase did not reach statistical significance. In view of the previously documented lack of association between DR4 (and other DR antigens) and RA in Greeks, the results suggest that some degree of HLA class II association exists with RA in this population at the DNA level which may not be overtly reflected serologically.

Adult↗
PubMed1990

Host defense during pregnancy: monocyte adherence and killing.

Pregnant women are more susceptible to candida infections than nonpregnant women. Since monocytes play a major role in host defense against candida, their association with radiolabeled candida and their capacity for killing candida were compared in sera of pregnant and nonpregnant women. While the basal rate of these monocyte functions was similar in both groups of women, candida opsonized with serum from pregnant women was less effective in enhancing these monocyte activities. Serum from nonpregnant women increased the association about twofold, whereas serum from pregnant women increased it only by about one and a half times in the two groups of women. Pretreatment of candida with serum from pregnant women increased the killing to 28%, whereas the serum from nonpregnant women was more effective, increasing the killing to 40%. The difference between the effect of the sera could not be attributed to the level of serum complement or IgG.

Adult↗
PubMed1989

Child abuse and neglect: an instrument to assist with case referral decision making.

A decision-making instrument was developed to assist reporting agencies and individuals in determining which child abuse and neglect charges would require immediate reporting to a child protection agency and which could be managed initially by the reporting agency. The instrument comprises a matrix scoring system that combines the experience classification of the reporting source and the degree of harm reported. The matrix scoring system was tested for 1 year to evaluate child abuse and neglect cases reported to the New York State Central Registry and Special Services for Children. The goal of the decision-making instrument is to decrease the number of unnecessary reportings to overburdened agencies without jeopardizing the interests of the child. The instrument should assist reporting sources in developing a systematic approach to case referral decision making and should minimize the subjectivity of such decisions.

Adolescent↗
PubMed1989

Detecting Chlamydia trachomatis in men with urethritis: serology v isolation in cell culture.

The accuracy of single serovar (L2) inclusion immunoperoxidase assay (IPA) to show serum IgG and IgA antibodies specific to chlamydiae was compared with culture for Chlamydia trachomatis to diagnose chlamydial infection in 73 men with acute urethritis. C trachomatis only was isolated from 18 (25%), Neisseria gonorrhoeae only from 17 (23%), and both organisms from six (8%). Thus 24 (33%) yielded chlamydiae. Assays based on IgG antibodies to chlamydiae at a titre of 1/64 or more showed high sensitivity (96%) and a good negative predictive value (80%), but low specificity (13%) and agreement (48%) compared with culture. IgG antibodies to chlamydiae at a titre of 1/128 or more showed lower sensitivity (75%) but higher specificity (72%), negative predictive value (79%), and agreement (73%). IgA antibodies to chlamydiae at a titre of 1/8 or more showed a sensitivity of 88%, specificity of 72%, negative predictive value of 88%, and agreement of 79%. An appreciable (fourfold or more) decrease in IgA and IgG titres was observed in most (10) of the 15 men from whom second blood samples were obtained one to two years after treatment. Measuring specific IgA and IgG antibodies to chlamydiae by IPA may serve as a useful complementary test for diagnosing and following up patients with urethritis.

Adolescent↗
PubMed1987

HLA associations with multiple sclerosis in Sicily and Malta.

The islands of Sicily and Malta have very different prevalence rates for multiple sclerosis (MS): at least 44 per 100,000 in Sicily and only 4 per 100,000 in Malta. In Northern Europe, MS is associated with HLA-DR2/Dw2. The other components of the commonest DR2-containing haplotype of this region, HLA-A3-B7-DR2-Dw2, also tend to be present at higher frequency in MS patients. HLA Class I and II antigen frequencies and associations in controls and MS patients from Sicily and Malta were studied to discover whether they might account for the difference in MS prevalence. In Sicilian MS patients, DR2 is increased in frequency compared with controls and four out of five DR2-positive patients also type as Dw2. In the Maltese population, DR2 is present at high frequency but approximately half of the DR2 positive individuals do not type as Dw2 so that DR2 is probably most commonly present as part of Class II haplotypes other than those commonly associated with MS. Additional differences in HLA profile of the Sicilian and Maltese populations were found when HLA-A, -B, and B-DR antigen associations were examined. Therefore, some of the difference in MS prevalence might be explained by genetic factors.

Cross-Sectional Studies↗
PubMed1986

A DR3-related DX alpha gene polymorphism strongly associates with insulin-dependent diabetes mellitus.

HLA-DQ alpha and HLA-DX alpha gene polymorphisms were analyzed by Southern blot techniques in 78 Caucasoid insulin-dependent diabetes mellitus (IDDM) subjects and 55 control subjects. Five restriction fragment length polymorphisms of the HLA-DQ alpha gene correlated with HLA-DR typing. Two allelic DX alpha-related gene fragments, of 2.1 kb (U) and 1.9 kb (L) in size were identified. Genotype frequencies in the IDDM group for UU, UL, and LL were 54%, 38.5%, and 7.5%, respectively, whereas the corresponding frequencies in the control group were 24%, 40%, and 36% (P less than 0.00005 for differences in genotype frequencies). The U allele was associated particularly with IDDM patients who were DR3, with healthy controls who were DR3, as well as with IDDM patients who were not DR3. Thus, if this DX alpha U allele is not the DR3-associated IDDM susceptibility gene, it is the closest marker hitherto studied.

Chromosome Mapping↗
PubMed1981

Sources of variance in the double normalized value: an evaluation of its reproducibility as a measure on HLA-D locus identity.

Two different sets of mixed lymphocyte culture (MLC) experiments were performed using HLA-D homozygous typing cells (HTC). In all stimulator-responder combinations the median cpm's of four replicate cultures were reduced into double normalized values (DNV). In the first experimental set the responder panel was unselected, whereas the responders for the second set were chosen on the basis of either sharing an HLA-D determinant with the stimulator (ID) or not (non-ID). The experiments were designed: Set 1: To estimate the technical variability in the DNV's and to observe the distribution of this variability. The standard deviation of an observation on a stimulator-responder combination was approximately 24 DNV units. Thus, by running 6 experiments on each responder we would have a mean DNV with a standard error of 10 DNV units. Set 2: To determine whether stimulators typing for the same Dw specificity had the same distribution of DNV's and to investigate the variability between responders, between experiments and within experiments. Although the mean DNV is the same for all HTC's, the variability in observations was greater for some HTC's than for others. The variability may be completely technical for some HTC's, whereas for other HTC's there is evidence of responder variability and between experiment variability. Important implications of these results are: (1) that in using a single cut-off value of 60 for all HTC to define typing responses one will have a very high misclassification rate for a large percentage of ID responders; (2) for some HTC this error rate can be reduced through repeating the experiment 4 times and raising the cut-off point; (3) this error, together with the technical and/or experimental variance can be further reduced by using 2 or more HTC's of the same specificity in each experiment and by combing their data; (4) misclassification can be reduced in every situation by doing 4 experiments, using 2 HTC per responder and computing a cut-off which gives a misclassification rate for each Dw type of 10% in ID's and in non-ID's. Thus the best approach to achieving Dw locus typing with a desirable low rate of misclassification would be to do similar control studies of every HTC, to estimate technical experimental and responder variance and then use this information to determine a cut-of value and the number of HTC's and experiments per responder required to keep the error rate at a satisfactory level.

Cells, Cultured↗
PubMed1979

HLA antigens in chronic relapsing idiopathic inflammatory polyneuropathy.

Observations are reported on 14 patients with a clinical diagnosis of recurrent or chronic relapsing idiopathic inflammatory polyneuropathy of Guillain-Barré type. The results suggest the possibility of a disease susceptibility gene for this disorder associated with the HLA-A1, -B8, -DRw3, and -Dw3 haplotype.

Chronic Disease↗