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Biomedical subjects

M C Jones

Publications and source records attributed to M C Jones.

At least 19 recordsLinked to original sources
PubMed1992

Deletions and microdeletions of 22q11.2 in velo-cardio-facial syndrome.

Velo-cardio-facial syndrome (VCFS), an autosomal dominant disorder, is characterized by cleft palate, cardiac defects, learning disabilities and a typical facial appearance. Less frequently, VCFS patients have manifestations of the DiGeorge complex (DGC) including hypocalcemia, hypoplastic or absent lymphoid tissue and T-cell deficiency suggesting that these 2 conditions share a common pathogenesis. Here, we report the results of cytogenetic and molecular studies of 15 VCFS patients. High-resolution banding techniques detected an interstitial deletion of 22q11.21-q11.23 in 3 patients. The remaining 12 patients had apparently normal chromosomes. Molecular analysis with probes from the DiGeorge Chromosome Region (DGCR) within 22q11 detected DNA deletions in 14 of 15 patients. In 2 families, deletions were detected in the affected parent as well as the propositus suggesting that the autosomal dominant transmission of VCFS is due to segregation of a deletion. Deletions of the same loci previously shown to be deleted in patients with DGC explains the overlapping phenotype of VCFS and the DGC and supports the hypothesis that the cause of these two disorders is the same.

Chromosome Banding↗
PubMed1992

Paraplegia and congenital contractures as a consequence of intrauterine trauma.

We present a newborn infant with paraplegia and contractures of the lower limbs, consistent with neurologic injury rather than malformation. The mother was involved in a severe motor vehicle accident during the sixth month of pregnancy. We propose that this infant's injuries are a result of that accident.

Accidents, Traffic↗
PubMed1992

Severe insulin resistance and diabetes mellitus in mandibuloacral dysplasia.

Mandibuloacral dysplasia (MAD) is a syndrome with onset in midchildhood. The predominant characteristics of MAD include flexion contractures; mandibular hypoplasia; loss of body fat; atrophic, speckled skin; and progressive osteolysis of the clavicles. We studied three males with MAD. Each had lipodystrophy of the extremities, with sparing of the face and neck. All had moderate hyperlipidemia. In response to oral glucose, each had a diabetic response, with peak insulin levels between 2870 and 22,960 pmol/L. Insulin-stimulated glucose disposal was determined in two patients with MAD. At an insulin infusion rate of 120 mU/m2 per minute, glucose disposal was less than 25% of that measured at similar levels of insulinemia in nondiabetic control subjects, indicating marked insulin resistance in patients with MAD. The insulin resistance occurred without obesity, excessive levels of counterregulatory hormones, or anti-insulin-receptor antibodies. We suggest that MAD is a previously undescribed form of lipodystrophic insulin-resistant diabetes mellitus.

Abnormalities, Multiple↗
PubMed1992

The sonographic appearances in postpartum thyroiditis.

During the postpartum period about 50% of women with circulating thyroid autoantibodies develop a transient autoimmune thyroiditis. To determine the sonographic appearances in postpartum thyroiditis (PPT), serial ultrasound (US) scans of the thyroid were performed in 135 postpartum women who were divided into three clinical groups: Group 1, 37 antibody positive subjects who developed PPT; Group 2, 28 antibody positive subjects in whom thyroid function remained normal; Group 3, 70 antibody negative controls. Thyroid hypoechogenicity was observed in 14/31 patients (45%) who were scanned between 4 and 8 weeks postpartum and who subsequently developed PPT (Group 1) compared with 4/24 patients (17%) in Group 2 (P less than 0.05) and 1/65 patients (1.5%) in Group 3 (P less than 0.001). In antibody positive patients, the positive predictive value of an abnormal scan during this period was 78%. Between 15 and 25 weeks postpartum thyroid hypoechogenicity was present in 32/37 patients (86%) in Group 1 compared with 11/28 patients (39%) in Group 2 (P less than 0.001) and 2/70 patients (3%) in Group 3 (P less than 0.001). Sonographic abnormality persisted beyond 32 weeks postpartum in 36/41 antibody positive patients (87%) who had exhibited thyroid hypoechogenicity earlier during the study and who had late scans. The characteristic US appearance in PPT is thyroid hypoechogenicity. The role of sonography in the prediction, diagnosis and follow up of patients with PPT is discussed.

Autoantibodies↗
PubMed1992

Cued speech.

Explore the source record for details and available documents.

Cues↗
PubMed1991

An analysis of the sequence of an infectious clone of rice tungro bacilliform virus, a plant pararetrovirus.

The nucleotide sequence of an infectious clone of rice tungro bacilliform virus (RTBV) DNA has been determined. The circular genome has 8002 bp and one strand contains four open reading frames (ORFs). One ORF is potentially capable of encoding a protein of 24 kD (P24) and has no initiation (ATG) codon. The other three ORFs potentially encode proteins of 12 kD, 194 kD and 46 kD (P12, P194, P46) respectively. The functions of P24, P12 and P46 are unknown. Comparative analyses with retroviruses and Commelina yellow mottle virus suggest that the 194 kD putative product is a polyprotein that is proteolytically cleaved to yield the virion coat protein, a protease and replicase (reverse transcriptase and RNase H) characteristic of retroelements. The DNA sequence reveals other features which strongly support our belief that RTBV is a pararetrovirus. These include sequences at the mapped positions of two discontinuities in the virion DNA which are complementary to tRNA metinit and purine-rich, and may be the priming sites for minus- and plus-strand DNA synthesis respectively. As the positions of likely transcriptional signals suggest, a full-length viral transcript is observed by northern analysis. The predicted folding of the 645 bp 5'-region of this RNA resembles that of caulimoviruses. Comparisons with other reverse transcribing elements are discussed.

Amino Acid Sequence↗
PubMed1991

Monoclonal antibodies to cultured human glomerular mesangial cells. I. Reactivity with haematopoietic cells and normal kidney sections.

The aim of this study was to produce monoclonal antibodies to cultured human glomerular mesangial cells in order to obtain specific markers for these cells and to aid the study of their function. Using standard monoclonal antibody techniques, 29 hybridomas producing antibodies directed to cultured mesangial cells were obtained. Most of these antibodies were not reactive with normal or neoplastic haematopoietic cell lines by flow cytometry. Fourteen of the 29 culture supernatants bound to various components of normal human kidney sections stained by the alkaline phosphatase/anti-alkaline phosphatase (APAAP) method. Ten of these supernatants reacted with components within the glomerulus, with six binding to the mesangium. These studies suggest that (1) mesangial cells in culture may show significant de-differentiation, because most supernatants which reacted with mesangial cells in culture did not do so in tissue sections; (2) antibodies reactive with haematopoietic cells may not detect the majority of immunogenic surface antigens on cells in tissues; and (3) some of the antibodies which we have produced may prove to be useful markers for mesangial cells in glomerular disease.

Animals↗
PubMed1991

Effect of cyclosporin A on immunoglobulin class in patients receiving blood transfusions.

IgG antibodies detected by flow cytometry in sera from potential renal transplant recipients are associated with an increased number of rejection episodes and impaired graft function. Furthermore, cytotoxic antibodies may develop if pre-transplant blood transfusions are given to such patients. We have investigated the effect of cyclosporin A on the development of IgM and IgG antibodies detected by flow cytometry after blood transfusions in 16 previously untransfused dialysis patients. Eight (group 1) received three to five third-party blood transfusions at two weekly intervals and the remaining eight (group 2) received transfusions with concomitant cyclosporin A therapy (10 mg/kg/day). Sera obtained after each transfusion were tested using flow cytometry against lymphocytes from six normal donors. In all 462 serum/cell combinations were tested. Sera from six out of eight patients in group 1 showed IgG antibody activity following blood transfusions and none developed IgM antibodies alone. In contrast IgG antibody activity was detected in one serum sample from only one of the eight patients in group 2 (P less than 0.02); a further three patients developed IgM but not IgG antibody activity during the transfusion protocol. IgG antibodies were found in 25/228 serum/cell combinations in group 1 but in 1/234 in group 2 (P less than 0.001). The patient in group 2 who developed IgG antibodies in one serum/cell combination was known to have red cell autoantibodies. This IgG activity was removed by red cell absorption, suggesting that the autoreactive red cell antibody cross-reacted with lymphocytes. Cytotoxic antibodies were detected in two serum/cell combinations in group 1 alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Formation↗
PubMed1991

Cyclosporin A and the humoral response to blood transfusion in the rat: definition of antigens which suppress alloantibody formation.

1. Blood transfusions improve renal allograft survival rates, but may induce antibodies which are directed to class I major histocompatibility complex antigens and mediate hyperacute transplant rejection. A model to study the development of such antibodies was developed in inbred strains of rats. 2. The influence of transplantation antigens shared between an initial course of blood transfusions, given with cyclosporin A, and a subsequent antigenic challenge (blood transfusion), given without cyclosporin A, on alloantibody responses to class I major histocompatibility complex antigens was then investigated. 3. Cyclosporin A administration prevented the development of alloantibodies to class I major histocompatibility complex antigens during the initial transfusion period. 4. After the challenge transfusions, alloantibody responses to class I major histocompatibility complex antigens were suppressed when class I major histocompatibility complex or minor histocompatibility antigens were shared between the initial and final transfusions. 5. This suppression only extended to third party class I antigens when minor histocompatibility complex antigens were shared between the initial and final transfusions. Sharing of class I or class II antigens had no effect on alloantibody responses to third party class I antigens coexpressed on the same cell. 6. These studies suggest that cyclosporin A given with blood transfusions may prevent clinical sensitization while permitting the development of suppressor activity, mediated by shared minor histocompatibility complex determinants, to a broad range of potential donor antigens.

Animals↗
PubMed1991

The effect of cyclosporin administered during a third-party blood transfusion protocol on humoral immune responses.

Antigen pre-treatment in animals undoubtedly prolongs graft survival. In man, however, routine pre-transplantation blood transfusions have recently become controversial, principally because of the adverse effect of transfusion-induced sensitisation on graft survival rates. We have monitored the effect of cyclosporin administered during a planned programme of third-party blood transfusions on the development of both cytotoxic and anti-idiotypic antibodies. A total of 24 patients were recruited to the study; ten received cyclosporin with blood transfusions (BT) (group 1), 14 received BT alone (group 2). Anti-HLA antibodies developed in 3 of 9 patients in group 1 and 8 of 12 patients in group 2 (P less than 0.05). Anti-idiotypic antibody activity was detectable in 9 of 9 patients in group 1 and 7 of 12 patients in group 2 (P less than 0.006). The mechanism by which cyclosporin can prevent an anti-HLA antibody response and promote an anti-idiotypic response is unclear.

Antibodies, Anti-Idiotypic↗
PubMed1991

Reduction of sensitization induced by blood transfusion in the rat by monoclonal antibodies.

Primary and secondary alloantibody responses were monitored in (AOxPVG)F1 hybrid rats after three transfusions of DA blood; the initial transfusion was either untreated or pretreated with monoclonal antibody directed to class I antigens or other cell surface markers. Mean antibody activity in recipient sera against class I DA antigens was significantly decreased by pretreatment with the monoclonal antibodies. The most marked suppression was associated with pretreatment by antibodies to the four major nonoverlapping epitopes of the RT1Aa antigen. Subsequent transfusions of DA blood failed to stimulate a secondary response. Crossreactivity of the alloantibody reactivity with BDIX antigens was diminished by pretreating the transfusions with rat anti-RT1A antibodies and, to a lesser extent, with a mouse monoclonal antibody (OX-18) to a common class I determinant. Monoclonal antibody pretreatment had no effect on the humoral response to class II DA antigens. These studies indicate that blood transfusions pretreated with monoclonal antibodies induce a less-potent cytotoxic humoral immune response and that reactivity is most effectively suppressed by completely masking the class I antigen. This technique may prove of clinical value in preventing the sensitization caused by blood transfusions in potential transplant recipients.

Animals↗
PubMed1991

Rice tungro disease is caused by an RNA and a DNA virus.

We present evidence that rice tungro spherical virus (RTSV) has a genome of polyadenylated single-stranded RNA of about 10 kb whereas rice tungro bacilliform virus (RTBV) contains double-stranded circular DNA. RTBV DNA has been mapped and shown to have two discontinuities, one in each strand, at specific sites; it thus resembles that of the caulimoviruses. Gel electrophoresis of RTSV preparations revealed two protein bands (Mr 35K and 26K). RTBV yielded two major protein bands of 37K and 33K together with several minor species of higher and lower Mr which react with antiviral serum.

Capsid↗
PubMed1990

Hepatoblastoma characterized by trisomy 20 and double minutes.

Karyotypic study of two hepatoblastomas revealed trisomies for chromosome 20 and the presence of double minutes (dmin). These cases are the second and third examples of trisomy 20 in hepatoblastoma and are the first examples of dmins in this rare childhood tumor.

Carcinoma, Hepatocellular↗
PubMed1990

The otolaryngologic manifestations of Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease is a condition of central nervous system dysmyelination. We describe a familial series in which both otologic and laryngologic abnormalities were present. The diagnosis of this invariably fatal disorder can be made on a clinical and/or pathologic basis. As the otolaryngologic manifestations are often the first to appear, the consulting head and neck surgeon may be essential in the initial diagnosis of this hereditary disease.

Audiometry, Evoked Response↗