Terminal 22q deletion associated with a partial deficiency of arylsulphatase A

A 7 month old girl with psychomotor retardation, hypotonia, and minor malformations was found to have a terminal deletion of the long arm of chromosome 22, del(22)(q13.31). The partial deficiency of arylsulphatase A (ARSA) and the normal level of NADH diaphorase 1 (DIA1) suggests that the ARSA locus can be regionally assigned to 22q13.31----qter and the DIA1 locus can be excluded from the same segment. This report is the third published case with a terminal 22q deletion.

Inhibitory effect of taxol, a microtubule stabilizing agent, on induction of DNA synthesis is dependent upon cell lines and growth factors

Growth-arrested rat fibroblasts, 3Y1, and human diploid fibroblasts, TIG-1, were induced to synthesize DNA by stimulation with various agents such as fetal bovine serum (FBS), epidermal growth factor (EGF), colcemid, or colchicine. Taxol, a microtubule-stabilizing agent, blocked the induction of DNA synthesis after stimulation with colcemid or colchicine in both cell lines. Taxol inhibited the induction of DNA synthesis after stimulation with FBS or EGF in TIG-1, but did not in 3Y1. 12-O-tetradecanoylphorbol-13-acetate (TPA) induced DNA synthesis in TIG-1, which was reduced only partly by taxol. Taxol stabilized or polymerized microtubules in both cell lines. These results indicate that the inhibitory effect of taxol on the induction of DNA synthesis varied among cell lines and among growth factors, and suggest that signal transduction processes may be differentiated by taxol sensitivity. In TIG-1 cells, when taxol was added within 6 h, about halfway into the initiation of DNA synthesis after the addition of FBS or EGF, the inhibition of DNA synthesis still occurred. Taxol did not inhibit the induction of c-fos and c-myc genes by FBS or EGF stimulation. Colchicine itself did not induce these genes in TIG-1. Thus, taxol appeared to inhibit the induction of DNA synthesis not by blockage in the early transduction process of the growth signal from the cell surface to nuclei but by blockage in processes operating in the mid- or late-prereplicative phase.

Evidence that gastric antisecretory action of lipopolysaccharide is not due to a toxic effect on gastric parietal cells

We have recently found that bacterial lipopolysaccharide (LPS) or endotoxin at minute doses inhibits the secretion of gastric acid and pepsin in rats. The present study was performed to determine whether this antisecretory action of LPS was a reversible biological response or a result of the destruction of gastric parietal cells by endotoxin. The intraperitoneal injection of LPS into pylorus-ligated rats resulted in a dose-related (40-4000 ng/kg) decrease in gastric acid secretion, with maximal inhibition being observed at a dose of 4000 ng/kg. The stomach then was examined both macroscopically and microscopically for the presence or absence of mucosal lesions or damaged gastric parietal cells. No morphological changes in the gastric mucosal structure including parietal cells were observed even in the rats injected with 4000 ng/kg of LPS. Next, basal gastric acid output was compared in the rats that had received LPS (4000 ng/kg, intraperitoneal) or saline alone 24 hr before. There was no significant difference in gastric acid secretion between the saline- and LPS-pretreated groups, indicating that the secretory capacity of gastric parietal cells returned to the control level at 24 hr after the injection of a maximal antisecretory dose of LPS. These results clearly suggest that the LPS-induced inhibition of gastric secretion results not from its toxic or destructive effect on the gastric secretory mechanism but from its reversible biological effect on gastric physiology.

The effect of neosurugatoxin on the release of neurohypophysial hormones by nicotine, hypotension and an osmotic stimulus in the rat

1. Experiments were carried out to test whether neosurugatoxin (NSTX) which blocks autonomic ganglia also acts centrally, like hexamethonium, on nicotinic cholinoceptors involved in the neural control of release of vasopressin and oxytocin from the neurohypophysis. 2. In the water-loaded rat under ethanol anaesthesia, nicotine 100 micrograms i.v. produced a pressor and an antidiuretic response accompanied by an increase in the urinary excretion of vasopressin and of oxytocin-like radioimmunoreactivity (OLRI). This indicates release of both vasopressin and oxytocin. 3. Under conditions in which tachyphylaxis was avoided, NSTX, 80 ng i.c.v., caused a prolonged inhibition of the release of both hormones by nicotine. 4. NSTX i.c.v. caused some reduction in the pressor response to nicotine. It is suggested that this response involves both central and peripheral stimulation of the sympathetic nervous system and that the central component is blocked by neosurugatoxin. 5. Muscarine, 40 ng i.c.v., produced a pressor and an antidiuretic response with increased urinary excretion of vasopressin and OLRI. All these effects were blocked by atropine but were not inhibited by NSTX. 6. Sodium nitroprusside (SN), 200 micrograms i.v., and hypertonic saline (HS; 1.54 M NaCl solution) 4 microliters i.c.v., both produced antidiuretic responses accompanied by increased urinary excretion of vasopressin and OLRI. The ratio of the excretion of vasopressin to that of OLRI was 5.1 +/- 1.3 (mean +/- s.e.: n = 8) for SN and 1.2 +/- 0.24 (mean +/- s.e.: n = 6) for HS.NSTX 80 ng i.c.v., caused a significant reduction in the antidiuretic response to the hypotension induced with SN: the increased urinary excretion of vasopressin was also significantly reduced but not that of OLRI. NSTX had no effect on the response to HS.7. We conclude that NSTX acts centrally on nicotinic cholinoceptors to block the release of vasopressin and oxytocin by nicotine and the release of vasopressin, but not that of oxytocin, by hypotension. It does not inhibit the release of either hormone by a central osmotic stimulus.

Tissue-specific mosaicism for trisomy 21 and congenital heart disease

Cytogenetic studies in a girl with ventricular septal defect and mosaicism for trisomy 21 showed that trisomy was present in most cells from the myocardium and lung but in only a minority from the skin and lymphocytes. These findings emphasize the importance of tissue-specific mosaicism as a cause of certain cardiovascular diseases.

Effect of pancreas transplantation on decreased levels of circulating bone gamma-carboxyglutamic acid-containing protein and osteopenia in rats with streptozotocin-induced diabetes

Diabetic osteopenia has been known as one of the chronic complications of diabetes mellitus, and a decrease in bone turnover has been thought to be one of the pathophysiological characteristics of this complication. In order to investigate the effect of long-term insulin therapy on low bone turnover in diabetes, pancreas transplantation was performed on streptozotocin-induced diabetic rats. Plasma levels of bone gamma-carboxyglutamic acid-containing protein(osteocalcin) in untreated diabetic rats were 0.9 +/- 0.1 (mean +/- SEM) nmol/l, significantly lower than the value of 4.2 +/- 0.6 nmol/l in control rats (p less than 0.01). Pancreas transplantation reversed this decrease to 6.3 +/- 1.1 nmol/l, which was not significantly different from the value in control rats. The circulating levels of calcitriol were significantly decreased in the untreated diabetic group (p less than 0.01), and the decrease was fully reversed by pancreas transplantation. In addition, the decreases in bone length, strength and weight were also improved by the transplantation. This evidence clearly shows that the improvement of metabolic derangements in diabetes by insulin is essential for the prevention of deterioration in diabetic osteopenia. It is possible, therefore, that insulin exerts an indirect beneficial influence through the metabolic amelioration on the decreases in bone turnover and circulating osteocalcin in diabetes mellitus, or has a direct stimulatory effect on the osteoblasts via the insulin receptor since its presence has been shown recently in osteoblastic cells.

Impaired glucose sensitivity of ATP-sensitive K+ channels in pancreatic beta-cells in streptozotocin-induced NIDDM rats

ATP-sensitive K+ channels (KATP channels) are known to play a key role in the cellular mechanism of insulin secretion from pancreatic beta cells. In order to examine the possible impairment of KATP channel function in non-insulin-dependent diabetes mellitus (NIDDM), we have studied the properties of the KATP channels in single beta cells of neonatally streptozotocin-induced diabetic rats (NSZ rats) using the patch-clamp technique. The unitary conductance of the channel in diabetic beta-cells was virtually identical to that in control beta cells and there was no difference in the sensitivity to ATP and glibenclamide of KATP channels between the NIDDM and control groups. In response to glucose, the activity of the KATP channels was diminished in a dose-dependent manner in both control and diabetic cells. However, the inhibition of the KATP channels in beta-cells of NSZ rats was significantly less than that in control cells. Even in the presence of 11.1 mM glucose, the openings of a few single KATP channels were consistently observed in cell-attached patch membranes of diabetic, but not control, beta-cells. Thus, it appears that the impaired insulinotropic action of glucose in beta-cells in NSZ rats is associated with a reduced sensitivity of the KATP channel to glucose, but not to ATP, presumably due to a deficiency in glucose metabolism.

Association of HLA-B51 and lack of association of class II alleles with Behcet's disease

Eighty-one Behcet's disease patients have been studied for HLA association by HLA-DRB1, -DQA1, -DQB1 and -DPB1 genotyping with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique and for NcoI RFLP in the tumor-necrosis factor (TNF beta) gene by Southern hybridization in addition to serological typing. In serological typing, the frequency of HLA-B51 was significantly increased in the patients. In PCR genotyping, there was a significant increase in the HLA-DRB1*0802, DQA1*0301 and DQB1*0303 alleles, whereas the frequencies of DRB1*1502, DQA1*0103, DQA1*0101, DQB1*0601 and DQB1*0501 showed a significant decrease in the patients. No significant difference was observed in any HLA-DPB1 alleles. Among them, B51 was found to be a genetic marker most strongly associated with Behcet's disease (p less than 0.00005, chi 2 = 46.47, pc[corrected p] less than 0.005). The positive and negative associations of class II alleles with the disease can be explained by linkage disequilibrium with B51, and do not reach statistical significance by the corrected p-value test. In NcoI RFLP typing in the TNF beta gene, 250 kb centromeric of the HLA-B gene, the frequency of a 5.5 kb fragment was considerably decreased in the patients when compared to the controls, although the decrease was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

A possible association between basic amino acids of position 13 of DRB1 chains and autoimmune hepatitis

Fifty-one patients with autoimmune hepatitis have been studied for HLA association by conventional serology and also by modified polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) genotyping. HLA-DR4 was significantly associated with autoimmune hepatitis (46 of 51 patients, 90.2%). DNA typing of the DRB1 gene for 43 DR4-positive patients by using the PCR-RFLP technique revealed that of 43 patients, 33 had DRB1*0405 (Dw15), five had DRB1*0406 (DwKT2), four had DRB1*0403 (Dw13a), two had DRB1*0401 (Dw4), two of 43 had DRB1*0407 (Dw13b) and one had DRB1*0408 (Dw14b). Thus, there was no significant difference in Dw frequencies between DR4-positive patients and DR4-positive healthy subjects. These findings suggest that the DR4-specific sequence (Val 11 and His 13 at amino acid positions 11 and 13, respectively), but not particular Dw-associated DR4 sequence, in the first domain of the DRB1 chain contributes to susceptibility to autoimmune hepatitis among Japanese. Interestingly, all five of the DR4-negative patients had the DR2 specificity (DRB1*1502 or 1601). Taken together, these results imply that the basic amino acids at position 13, which is present only on the DR2 and DR4 B1 molecules (Arg on DR2 and His on DR4), are most important for determining the predisposition to autoimmune hepatitis.

Enhancement of murine hematopoiesis by synergistic interactions between steel factor (ligand for c-kit), interleukin-11, and other early acting factors in culture

Entry into the cell cycle of dormant hematopoietic progenitors appears to be regulated by multiple synergistic factors, including interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF), IL-11, and the ligand for c-kit, which is also known as steel factor (SF). We have tested the effects of these and other hematopoietic factors on the proliferation of partially enriched dormant murine progenitors in the presence and absence of serum. In serum-containing cultures, SF and IL-11 interacted to support the formation of multilineage colonies; the level of colony formation was comparable with the colony formation supported by other effective two-factor combinations. In serum-free cultures, colony formation supported by two factors was significantly less than that in serum-containing culture and the most effective two-factor combination in serum-free culture was SF plus IL-3. In serum-free cultures, three-factor combinations consisting of SF, IL-3, and one of IL-6, G-CSF, or IL-11 yielded colony formation that was comparable with that seen in serum-containing cultures. These studies indicate that IL-11 belongs to a group of early-acting hematopoietic synergistic factors that now includes IL-6, G-CSF, and IL-11. In contrast, SF is unique among the synergistic factors in that it interacts either with growth factors such as IL-3 or GM-CSF or with synergistic factors such as IL-6, IL-11, or G-CSF.

Inhibition by neosurugatoxin and omega-conotoxin of acetylcholine release and muscle and neuronal nicotinic receptors in mouse neuromuscular junction

Neosurugatoxin and omega-conotoxin, known to be specific ligands for the neuronal nicotinic receptor and Ca2+ channel, respectively, were previously claimed to exert no depressant action on the mouse neuromuscular junction. It was found that in preparations partially blocked with tubocurarine or with low Ca(2+)-high Mg2+ Tyrode's, both toxins, at 3-10 microM, depressed indirect twitches and either produced wanings (neosurugatoxin) or waxings (omega-conotoxin) of indirectly elicited tetanic contractions whilst in normal Tyrode's the contractile forces were not changed. In normal Tyrode's, neosurugatoxin decreased the amplitudes of spontaneous and evoked endplate potentials and enhanced the run-down of endplate potentials as did tubocurarine though with lesser potency. By contrast, omega-conotoxin (10 microM) decreased the amplitude of the evoked but not of the spontaneous endplate potential in low Ca(2+)-high Mg2+ Tyrode's, and produced facilitation of endplate potentials, instead of run-down, on repetitive stimulations. Higher concentrations of omega-conotoxin appeared to depress quantal release in normal Tyrode's. The effects were all reversible. The prolonged endplate depolarization found in preparations treated with neostigmine or 3,4-diaminopyridine, was partially depressed by both toxins. The results suggest that neosurugatoxin blocks the neuron and muscle nicotinic receptors in the neuromuscular junction with comparable potency. The pharmacology of the nicotinic receptor on motor nerve terminal seems more similar to the muscle nicotinic receptor than to that on autonomic ganglia or brain. On the other hand, omega-conotoxin seems to block a small fraction of Ca2+ channels on the motor nerve and decreases the quantal release of evoked endplate potentials.

Influences of ventricular pacing on hemodynamics, myocardial metabolism, and cardiac work efficiency: potential risks of rate-responsive ventricular pacing

The influences of ventricular pacing at a rate of 70 beats/min (bpm) on the systemic and coronary hemodynamics, myocardial metabolism, and cardiac work efficiency were evaluated in five patients with bradycardia. The results were compared to those obtained in six normal subjects at rest. In order to elucidate the effects of a relatively high rate of ventricular pacing, cardiovascular and metabolic variables were also obtained at 120 bpm in the normal subjects. It was observed that the patients eventually benefited from ventricular pacing at a rate of 70 bpm and improved in systemic hemodynamics. Although coronary hemodynamics and myocardial metabolism were accelerated, the cardiac work efficiency was not improved. A pacing rate of 120 bpm in the normal subjects did not appear to accelerate systemic hemodynamics, but adverse accelerations of coronary hemodynamics and myocardial metabolism were observed, and the cardiac work efficiency was remarkably reduced as a result. Our observations indicated that the coronary reserve capacity was very important for ventricular pacing, and suggested that an undue increment of the pacing rate not only might be meaningless but also might induce ischemic angina. Therefore, we should be cautious in using a rate-responsive pacing mode, particularly in determination of the upper limit of pacing rates, although many benefits with this pacing mode have recently been advocated.

Lack of deletion of complement C4 and steroid 21-hydroxylase genes in Japanese patients with primary Sjögren's syndrome

A null allele at C4A (C4AQO) is associated with primary Sjögren's syndrome (SS) in Japanese. Since a deletion of the C4A and CyP21A genes is reported to account for C4AQO in patients with systemic lupus erythematosus (SLE) in Caucasians, we studied the restriction fragment length polymorphism (RFLP) of genomic DNA to determine whether similar deletions of the C4A and CyP21A genes occur in Japanese patients with SS. Patients with C4AQO did not show the extensive deletion of C4A and CyP21A, which would be recognized by the appearance of 8.5 kb/HindIII and 6.4 kb/TaqI fragments hybridizing with a C4 probe. It is yet to be shown whether the lack of expression of C4A genes in Japanese patients with primary SS is due to point mutations, or to small deletions or insertions that were not detected by the RFLP approach.

HLA-DRB1 genotyping by modified PCR-RFLP method combined with group-specific primers

We previously introduced HLA-DQA1, -DPB1 and DQB1 genotyping with the modified PCR-RFLP method using some informative restriction enzymes which have either a single cleavage site or alternatively no cleavage site in the amplified DNA region, depending on the HLA alleles, making reading of RFLP band patterns much easier. In this study, 43 HLA-DRB1 alleles, excluding DRB1*1103 and *1104 for which no restriction enzymes are available to distinguish each from the other, could be defined by this modified PCR-RFLP method combined with 7 pairs of group-specific primers. It is impossible to distinguish DRB1*0701 and DRB1*0702 as they are identical for the second exon of DRB1. For DR1-DRB1, DR2-DRB1, DR4-DRB1, DR7-DR1, DR9-DRB1, DRw10-DRB1 or DRw52 associated antigens (DR3, w11, w12, w13, w14, and DRw8)-DRB1 gene amplification, the second exon of the DRB1 gene was selectively amplified using each group-specific primer from genomic DNAs of 70 HLA-homozygous B-cell lines and healthy Japanese by PCR. Amplified DNAs were digested with restriction endonucleases and then subjected to electrophoresis assaying simply for cutting, or no cutting, of the DNA, although some alleles can be distinguished only after examination of RFLP band patterns generated and in some cases using double digestion technique with two restriction enzymes. This modified PCR-RFLP method can be successfully applied to all possible DRB1 heterozygotes, despite the fact that 15 pairs of heterozygotes among them cannot be distinguished theoretically by the PCR-SSO method, because the PCR-RFLP method can tell whether two polymorphic sites are linked to each other (cis position) or located on a different chromosome (trans position) by checking the length of RFLP bands generated with double digestion. Thus, the PCR-RFLP method is technically simple, practical and inexpensive for determination of the HLA-DRB1 alleles for routine HLA typing work.

Development and characterization of a human monoclonal antibody probably detecting the leukocyte differentiation antigen CD39

A human monoclonal IgM antibody, referred to as TU223, has been produced. The reactivity of TU223 was tested in various cells and cell lines by complement-dependent microcytotoxicity test and fluorescence-activated cell sorter analysis. The antigen defined by TU223 was expressed on Epstein-Barr virus-transformed B-cell lines and on some Burkitt's lymphoma cell lines, but was not expressed on normal T cells, B cells or erythrocytes. In addition, expression of the antigen defined by TU223 was also induced on B cells activated by Epstein-Barr virus or pokeweed mitogen, and on T cells activated by phytohemagglutinin, concanavalin A, pokeweed mitogen or recombinant interleukin-2. However, no expression of the antigen detected by TU223 was induced at all on recombinant interleukin-4-treated B cells or macrophage-like cell line U937. When the ability of TU223 and various mouse monoclonal antibodies to bind to human differentiation antigens was compared, interestingly, the reactivity of TU223 was found to be very similar to that of mouse monoclonal antibody CD23 (H107), which reacts with Fc epsilon receptor II. Two-color analysis revealed that the antigen defined by TU223 is expressed on the cell surface of certain lymphoid cells expressing CD23 antigen. However, it can be concluded that the antigen defined by TU223 is clearly distinct from Fc epsilon receptor II, based on assay of cross-blocking between H107 and TU223. The surface antigen on B85 cells recognized by TU2232 had the molecular size of 80-82 kiloDaltons as determined by immunoblotting analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing the efficacy of DeVega's annuloplasty for secondary tricuspid regurgitation

DeVega's annuloplasty was performed on 41 patients with tricuspid regurgitation (TR) associated with combined valvular disease and results were assessed based on Doppler echocardiographic findings in an attempt to examine the applicability of this surgical technique. TR was quantitatively evaluated via Doppler echocardiography before and after surgery. Clinical symptoms, cardiac function, and surgical results were assessed, and the severity of left ventricular myocardial degeneration was determined using electron microscopy. There were no differences in the following factors between the TR recurrence and TR improvement groups: previous heart surgery, number of involved valves, presence or absence of a giant left atrium, preoperative New York Heart Association (NYHA) functional class, and type of prosthetic valve (Björk-Shiley vs. St. Jude Medical). We found no differences between these two groups in TR severity and tricuspid annulus diameter measured during surgery. Severity of myocardial degeneration was closely associated with the recurrence of TR. Clinically, most had diminished cardiac function before surgery. DeVega's technique appears to be remarkably effective in patients with well-preserved myocardium because no TR recurrence was detected even in examinations with the most accurate Doppler echocardiography. However, such long-term effectiveness of DeVega's technique cannot be expected in patients with degenerated myocardium.

Primary epidural non-Hodgkin's lymphoma in clinical stage IEA presenting with paraplegia and showing complete recovery after combination therapy

A 70-year-old man was admitted to our hospital because of paraplegia. A spinal epidural tumor (Th VII-XI) was diagnosed by magnetic resonance imaging and resected. Histological examination of the tumor showed non-Hodgkin's lymphoma of the diffuse large cell type (Lymphoma Study Group classification), with a B cell phenotype. The clinical stage was IEA by the Ann Arbor classification. Radiation therapy of the involved field was performed (total dose: 40 Gy), followed by six courses of modified cyclophosphamide, adriamycine, vincristine, prednisolone (CHOP) therapy. He was discharged walking unaided 10 months later and has shown no evidence of relapse in the 26 months since discharge.

Basic fibroblast growth factor (bFGF) acts centrally in the brain to inhibit gastric emptying in rats

In the present study, we evaluated the central nervous system action of basic fibroblast growth factor (bFGF) on gastric emptying of a liquid meal in conscious rats using a Phenol red method. Intracisternal injection of bFGF dose-dependently inhibited gastric emptying, while intraperitoneal injection of bFGF at the same doses failed to alter gastric emptying. These results suggest for the first time that bFGF acts in the central nervous system to delay gastric emptying.

Growth hormone deficiency and empty sella syndrome in a boy with dup(X) (q13.3----q21.2)

A 2 8/12-year-old boy with severe growth failure and mental retardation was found to have a maternally derived tandem duplication of the long arm of X chromosome, dup(X) (q13.3----q21.2). Karyotypic interpretation was further confirmed in this patient by a double gene dose for red blood cell phosphoglycerate kinase. DNA replication study showed that the duplicated X chromosome was always late replicating in peripheral blood lymphocytes as well as in skin fibroblasts from the mother. Endocrine studies in the patient demonstrated growth hormone deficiency. Magnetic resonance imaging of the head then disclosed the empty sella syndrome. This appears to be the first report of a dup(Xq) patient associated with a growth hormone deficiency and the empty sella syndrome. We emphasize that duplication of the proximal Xq in males represents another microduplication syndrome (Thode-Leonard syndrome).

De novo complex chromosome rearrangement in identical twins with multiple congenital anomalies

A de novo and apparently balanced complex chromosome rearrangement (CCR) was found in monozygotic (MZ) twin infants with multiple congenital anomalies. The rearrangement involved 4 chromosomes with 6 breakpoints including 2p23, 2q13, 2q21.1, 3p23, 11q13.1, and 12q24.1. This seems to be the first report of a CCR in MZ twins. The relationship between this chromosome abnormality and MZ twinning is discussed.

Search for MHC-associated genes in human: five new genes centromeric to HLA-DP with yet unknown functions

Taking advantage of five mouse genomic or cDNA probes [KE5(probe 14), KE4 (probe 11), KE3 (probe 7), KE2 (probe 5), and SET] mapped on the H-2K region in mouse, we have identified and localized homologues of these five genes in the human major histocompatibility complex region (HKE5, HKE4, HKE3, HKE2, and HSET, respectively). Cosmid cloning and pulsed field gel electrophoresis analyses indicated that a human homologous gene, HKE5, is located 10 kilobases (kb) centromeric of the alpha 2 (XI) collagen (COL11A2) gene followed by HKE4. HKE3, closely linked to HKE2, is located 170 kb centromeric of HKE4. Furthermore, HSET is located 50 kb centromeric of HKE2. This gene organization outside the DP subregion is completely identical to that of the mouse H-2K region centromeric of I-Pb3, a mouse homologue of the DPB gene, except the lack of genes corresponding to the H-2K and -K2 genes in human.

Unique karyotypes in two patients with Prader-Willi syndrome

A physical disruption of the Prader-Willi syndrome (PWS) chromosome region is thought to cause PWS. We describe 2 girls with PWS phenotype, who had unique chromosome 15 abnormalities. The first patient showed mosaicism: 45,XX,t(15;15)(qter----p11.1::q11.200----qter)/46,XX,t(15;15)(qter----p1 1.1::q 11.200----qter), +mar. The band 15q11.2 apparently remained intact in the t(15;15) chromosome, and the mar chromosome was considered as r(15) (p11.1q11.1). The second patient had a karyotype of 47,XX,del(15)(q11.200----q11.207), +idic (15)(pter----q11.1::q11.1----pter). The complex breakage and reunion involving the 15q11.2 regions of the father's homologous chromosomes 15 at meiosis appeared to have resulted in the idic(15) and the del(15) chromosomes. These cytogenetic findings suggest that the PWS chromosome region may be localized on the very proximal portion of band 15q11.2.

Demonstration of the requirement for self antigen in the activation of autoreactive T cells

An HLA-DR4-restricted T cell clone (26G11), which was reactive to autologous non-T cells without any nominal antigens, was established from an unimmunized normal subject that was DR1/4 positive. The reactivity of the clone was examined against L cells (LDR4) transfected with the particular DR4 genes obtained from the same subject. 26G11 cells proliferated slightly in response to LDR4 cells, but the proliferation was markedly augmented by the addition of cell lysate from an autologous B cell line. In addition, 26G11 cells killed LRD4 cells sensitized by preincubation with the cell lysate more efficiently than LDR4 cells without treatment. When LDR4 cells were preincubated with cell lysate from allogenic B cell lines, effective killing of the target cells by clone 26G11 was also observed. These data strongly suggest that this autoreactive T cell clone (26G11) recognizes endogenous antigen in the context of the DR4 molecule. This directly demonstrates the requirement for self antigen in the activation of human autoreactive T cells from a normal subject.