Evidence, from family studies, for linkage disequilibrium between TGFA and a gene for nonsyndromic cleft lip with or without cleft palate

The inheritance of alleles of the transforming growth factor alpha (TGFA) locus has been studied in families affected with cleft lip with or without cleft palate (CL/P), by using the transmission/disequilibrium test described by Spielman and colleagues. Only heterozygous parents with an affected child can be included in this test, but within such families a significantly greater frequency of C2 alleles were transmitted to affected children than would be expected by chance. There was no evidence that the total number of C2 alleles transmitted to affected and unaffected children differed significantly from random segregation. These data provide evidence from within families that a gene for susceptibility to CL/P is in significant linkage disequilibrium with the C2 allele of the TGFA locus.

P1 and cosmid clones define the organization of 280 kb of the mouse H-2 complex containing the Cps-1 and Hsp70 loci

A 280 kilobase (kb) contig was isolated from mouse genomic P1 and cosmid libraries, using as probes human cDNA and genomic DNA fragments that map in the interval between the second component of complement and tumor necrosis factor genes of the HLA complex. The clone contig demonstrates synteny of eleven mouse genes that are homologous to genes initially mapped within the human major histocompatibility complex. These include the mouse homologs of BAT2 (HLA-B-associated transcript 2) through BAT9 and also three HSP70-related genes. Five P1 clones form a contig of 240 kb that spans from BAT9 through BAT3. Twelve cosmid clones are arranged in three contigs that confirm most of the structure of the P1 contig and link the mouse BAT3 homolog to the BAT2 homolog approximately 15 kb farther telomeric. Polymorphic DNA markers within the cloned region were used to map the cleft palate susceptibility-1 (Cps-1) locus to the interval between Hsp70.1 and BAT6 (valyl-tRNA synthetase). This refines the location of the Cps-1 locus to a 45 kb region contained in the H2-124 P1 insert.

Association between alleles of the transforming growth factor-alpha locus and the occurrence of cleft lip

DNA samples from 100 patients with cleft lip with or without cleft palate (CL/P) were compared with those of 98 unaffected control individuals with respect to transforming growth factor alpha (TGFA) genotypes. Among the Caucasians in this population (83 CL/P, 84 controls), there was a significant difference in the restriction fragment length polymorphisms (RFLPs) observed after digestion with TaqI (chi 2 = 4.68, P = 0.03). The frequency of the C2 allele in the Caucasian CL/P population was 0.169, whereas that in the control group was 0.089. When the data for Caucasians, African-Americans, and Asians were examined jointly, the chi 2 value for the pooled sample was 5.08 (P = 0.02). This confirms the hypothesis of Ardinger et al. [1989, Am J Hum Genet, 45:348-353] that TFGA itself or a closely linked gene contributes to the development of CL/P in humans.

Purified antichick Thy-1 IgG abolishes intermediate and long-term memory

One- to 2-day-old chicks administered purified antichick Thy-1 IgG showed substantial amnesia for a single-trial passive discriminated avoidance task. Amnesia was clearly evident at 30 min after learning, during the intermediate stage of a three-stage model of memory processing, and persisted for at least 3 h. A similar effect was also observed with Fab and F(ab')2 fragments. Fc fragments, the non-IgG fraction of ascites, and saline yielded normal retention levels at all times. These results contrast with our earlier reports that both polyclonal and monoclonal antibodies to chick Thy-1 inhibited long-term memory formation only. The present findings are interpreted as possibly representing a dual effect of the purified IgG.

CT-guided stereotactic injection of radionuclide for treatment of brain tumors

The authors report on 40 brain tumor patients treated with CT-guided stereotactic injection of 198Au and 32P. Among the 40 cases were astrocytoma in 23 cases, craniopharyngioma in 9, meningioma in 4, pituitary adenoma in 2, and pinealoma and metastatic carcinoma each in 1 case. The tumors were all located in deep or important areas of the brain which were difficult to deal with by conventional operation. 62 injections of colloidal isotopes were performed, and all were successful. No major adverse effects or complications occurred on follow-up of 6-12 months, 28 patients were improved in their clinical symptoms, and CT scanning showed that the tumor sizes were diminished. The effective rate is 70%.

Definition of myasthenogenic sites of the human acetylcholine receptor using synthetic peptides

Experimental autoimmune myasthenia gravis (EAMG) and antibodies that modulate AChRs from cultured human muscle are induced by a disulfide-looped peptide comprising the human acetylcholine receptor (AChR) alpha-subunit residues 125-147 (H alpha 125-147). To delineate the essential antigenic requirements for induction of EAMG by this peptide, a series of peptides was synthesized: (a) a nonlooped analog (Cys 128 replaced by Ser) stimulated modulating autoantibodies, induced EAMG, and bound antibodies induced by native AChR; (b) H alpha 131-147, a heptadecylpeptide shorter by 6 N-terminal residues, induced modulating antibodies, EAMG, and T cells that responded to H alpha 125-147, but not to H alpha 137-147; (c) H alpha 137-147, an undecapeptide shorter than H alpha 125-147 by 12 N-terminal residues, did not stimulate T cells or induce antibody production, but it bound antibodies generated by the longer peptides. Thus, when coupled to an epitope that could stimulate helper T cells, the region 137-147 was able to stimulate B cells. This study has defined a myasthenogenic region of the human AChR's alpha-subunit, 17 amino acids long, that contains several distinct epitopes, including at least one N-terminal site inducing T-cell responses (region 131-136) and two possibly overlapping sites that induce antibodies (regions 131-136 and 137-147). Further definition of antigenic sites inducing helper and suppressor T-cell responses and stimulating production of autoantibodies to AChR is essential to the goal of antigen-specific immunotherapy for myasthenia gravis.

Multiecho magnetic resonance angiography

Several pulse sequences which generate projected MR angiograms are presented. These pulse sequences exploit multiple-gradient refocused echoes to obtain several independent angiograms, which can be combined or separately analyzed to provide more information than an individual angiogram. For example, a series of angiograms, each with a different projection axis, can be obtained in the time required to obtain a single angiogram using a single-echo method. If the view angle of each echo is the same, then the acquired angiograms can be added to enhance the signal-to-noise ratio. Another pulse sequence simultaneously obtains two or more angiograms, sensitive to orthogonal flow components of the overall blood flow. These angiograms are then added to give an angiogram which is sensitive to flow in all directions.

Polychlorinated Biphenyl Dechlorination in Aquatic Sediments

The polychlorinated biphenyl (PCB) residues in the aquatic sediments from six PCB spill sites showed changes in PCB isomer and homolog (congener) distribution that indicated the occurrence of reductive dechlorination. The PCB dechlorinations exhibited several distinct congener selection patterns that indicated mediation by several different localized populations of anaerobic microorganisms. The higher (more heavily chlorinated) PCB congeners that were preferentially attacked by the observed dechlorination processes included all those that are either pharmacologically active or persistent in higher animals. All the lower (less heavily chlorinated) PCB congeners formed by the dechlorinations were species that are known to be oxidatively biodegradable by the bacteria of aerobic environments.

Endplates after esterase inactivation in vivo: correlation between esterase concentration, functional response and fine structure

Mouse sternomastoid muscles were incubated with diisopropylfluorophosphate (DFP) in vivo, and the time course of recovery was studied using histochemistry, EM autoradiography and physiology. We found that: (1) the ability of the muscle to sustain tetanus in response to nerve stimulation is eliminated when the esterases at the neuromuscular junctions are saturated with DFP. This ability is regained partially when less than 10% of the DFP-binding sites have recovered. (2) There is a positive correlation between the frequency of stimulation at which the tetanic response can be maintained and the extent of acetylcholinesterase (AChE) recovery. (3) Tetanic responses at fusion frequency (about 100 Hz) appear indistinguishable from controls with only about 25% of normal AChE. (4) Butyrylcholinesterase (BuChE) possibly of Schwann cell origin recovers more rapidly than does AChE. (5) The muscle shows fine structural changes involving Z band dissolution and the breakdown of sarcoplasmic reticulum within hours after esterase inactivation. (6) This myopathy reaches a peak at three days after esterase inactivation and is almost fully recovered by two weeks. (7) It can be eliminated if, at the time of esterase inactivation, the nerve is cut or the acetylcholine receptors at the endplate are inactivated by alpha-bungarotoxin. We suggest that the myopathy, seen after DFP, is mediated by Ca2+ fluxes due to prolonged action of acetylcholine (ACh) in the absence of esterases.