Delta-thalassemia caused by disruption of the site for an erythroid-specific transcription factor, GATA-1, in the delta-globin gene promoter

Delta-thalassemia is a complex group of inherited disorders of globin genes characterized by impaired synthesis of the delta-globin chain. The T-C substitution was detected at position -77 of the delta-globin gene isolated from three independent Japanese individuals who were homozygotes for delta-thalassemia. To elucidate the significance of the mutation in delta-globin gene expression, we investigated the genotype of three delta-thalassemia homozygotes and 58 normal individuals using dot blot hybridization of the polymerase chain reaction (PCR)-amplified DNA. The mutation was observed in six alleles of three homozygotes, while no mutation was detected in 116 alleles of normal individuals, thereby indicating the close association of this mutation with the thalassemia phenotype. Since the mutation (TTATCT-TCATCT) is located within the inverted binding motif of GATA-1 (T or A-G-A-T-A-G or A), an erythroid cell-specific transcription factor, we did gel retardation assays using nuclear extracts from the erythroid cells. We found that GATA-1 binds the oligonucleotide spanning positions -61 to -90, but does not bind to the oligonucleotide with the mutation at position -77. Competition gel retardation assays showed that GATA-1 binding can be competed out by the fragment with the GATA-1 motif, but not with the mutant oligonucleotide. Analysis of the transient expression of the CAT gene linked to the delta-globin gene promoter region demonstrated that the construct with the mutant promoter region was expressed about 20-fold less compared with the normal one. Thus, the mutation at position -77 impairs delta-globin gene expression by abolishing GATA-1 binding to the AGATAA sequence of the promoter region of the delta-globin gene. This provides a good example of involvement of tissue-specific transacting factors in the molecular pathogenesis of hereditary diseases.

Inhibition of neuromuscular transmission in isolated mouse phrenic nerve-diaphragm by the enterotoxin of Clostridium perfringens type A

The enterotoxin of Clostridium perfringens type A, a channel forming protein toxin, inhibited neuromuscular transmission under conditions of low calcium. Twitch tension of isolated phrenic nerve-diaphragm preparations elicited by electrical stimulations to the phrenic nerve was recorded isometrically, and the preparations were exposed to the purified enterotoxin. In Krebs solution containing 0.5 mM calcium, the enterotoxin (20 micrograms/ml) reduced within 10 min the amplitude of the twitch tension to 34 +/- 7% (mean +/- S.D., n = 11) of that recorded before the treatment. The effects of the enterotoxin on the twitch tension were irreversible and proceeded independently of stimulation. The reduction of the twitch tension by the enterotoxin was apparent in Krebs solution containing less than 0.6 mM calcium and the degree of reduction was inversely related to the concentration of calcium. The reduction of the twitch tension by the enterotoxin was also dependent on temperature and concentration of the toxin. At temperatures below 20 degrees C, no obvious reduction of twitch tension was observed with 20 micrograms/ml of the enterotoxin. Enterotoxin at a concentration of 0.4 micrograms/ml caused 16 +/- 2% (mean +/- S.D., n = 4) reduction of twitch tension, and the degree of the reduction in twitch tension increased with toxin concentration, reaching a plateau of 65 +/- 4% (mean +/- S.D., n = 7) at 6.5 micrograms/ml of the enterotoxin. The effects of the enterotoxin were antagonized by 2 microM physostigmine. Unlike curare, pretreatment of the preparation with enterotoxin did not antagonize the neuromuscular block by decamethonium. Neither the tension of muscular twitch elicited by direct electrical stimulation to the muscle nor the resting membrane potentials of muscle fibers recorded intracellularly were affected by the enterotoxin. The enterotoxin (2.2 micrograms/ml) reduced the frequency, but not mean amplitude or amplitude distribution, of miniature end-plate potentials, from 0.91 +/- 0.07/sec to 0.72 +/- 0.07 (mean +/- S.E., n = 5). The results suggest that the enterotoxin will provide a novel tool for the studies on the mechanism of the neuromuscular transmission because of the unique characteristics of the inhibition and of the known mechanism of its action on the cell membrane.

Two species of human CRK cDNA encode proteins with distinct biological activities

Two distinct human CRK cDNAs, designated CRK-I and CRK-II, were isolated from human embryonic lung cells by polymerase chain reaction and by screening of a human placenta cDNA library, respectively. CRK-I differed from CRK-II in that it lacked a 170-nucleotide sequence, suggesting that CRK-I and CRK-II were the products of alternative splicing. The amino acid sequences deduced from these two cDNAs differed in the carboxyl termini and contained one SH2 and either one or two SH3 domains. RNAse protection analysis demonstrated both CRK-I and CRK-II mRNAs in various human cells. Three CRK proteins, of 42, 40, and 28 kDa, were identified in human embryonic lung cells by means of antibodies against the SH2 region and the SH3 region of the bacterially expressed CRK-I protein. Transient expression of CRK-I and CRK-II cDNAs in COS7 cells showed that the former encoded the 28-kDa protein and the latter encoded the 40- and 42-kDa proteins. All human cell lines so far examined expressed the 40-kDa protein; however, expression of the 28- and the 42-kDa proteins was variable. In a comparison of the biological activity of the two human CRK proteins, both proteins were stably expressed in rat 3Y1 cells. All cell lines expressing CRK-I protein showed altered morphology, proliferated in soft agar, and grew as massive tumors in nude mice. Although CRK-II-expressing cells showed a slight morphologic change, they did not make colonies in soft agar or grow in nude mice. These results demonstrate that the two species of human CRK cDNA encode proteins which differ in their biological activities.

Isolation of secretory IgA from feline bile and bile IgA levels in growing cats

Secretory IgA was isolated from feline bile, using ammonium sulphate precipitation, gel-filtration chromatography and affinity chromatography. It formed a precipitating line between anti-cat whole serum or anti-cat bile serum by immunoelectrophoresis and double diffusion. It consisted of three subunits that molecular weight were 80 kd, 62 kd and 27 kd by SDS-PAGE analysis. The 80 kd protein was equivalent to secretory component of human and other animals. Immunoglobulin levels were observed on bile collected continuously by gallbladder cannulation in growing cats. Although immunoglobulins were not detected in bile of feline fetus, after birth its levels increased gradually. Biliary IgA levels reached the adult levels earlier than that of their serum.

Calmodulin is involved in catecholamine secretion from digitonin-permeabilized bovine adrenal medullary chromaffin cells

The role of calmodulin in exocytotic secretion was studied using digitonin-permeabilized bovine adrenal medullary chromaffin cells. Addition of calmodulin to the permeabilized cells increased Ca(2+)-dependent norepinephrine release in a dose-dependent manner. Unlike calmodulin, addition of caldesmon, actin or bovine serum albumin did not increase the release. Calmodulin increased the release at Ca2+ concentrations of more than 10(-6) M and its effect increased with increase in Mg2+ concentration. Th release of norepinephrine enhanced by calmodulin was inhibited by tetanus toxin, which specifically inhibits exocytotic secretion. These results indicate directly that calmodulin plays an important role in exocytotic secretion from chromaffin cells.

Scanning electron microscopic and light microscopic observations on morphological changes of freeze-dried bone implantation in rats: comparison with fresh autogenous bone transplantation

Bone remodelling after the implantation of freeze-dried autogenous bone in rat parietal bone was compared with fresh autogenous bone transplantation, using a scanning electron and light microscope revealed the time intervals after transplantation/implantation. The light microscope revealed the time delay of the bone remodelling in the implantation, compared with the transplantations. The scanning electron microscope showed that the differences between the two groups were in the states of bone union and bone resorption. In the fresh bone group, the newly-formed bone filled the spaces between host and the transplanted bones at 2 to 3 weeks after the transplantation: the newly-formed bone fused and melted into the transplanted bone. New bone formation was more dominant on the bone surface in the dura mater side than in the skin side. The union was almost completed at 5 weeks. In freeze-dried bone implantation, the bone union in the contact space was very poor and the implanted bone was mainly covered by the new bone, which developed from the host bone surface in the dura mater side at 2 to 3 weeks after the implantation. What is noteworthy is that bone resorbed areas showing numerous Howship's lacunae were mainly observed on the host bone surface in the vicinity of newly-formed bone. However in freeze-dried bone implantation, the bone resorption was greater on the host and implanted bone surface than that of fresh bone transplantation: the resorption of host bone was considerably larger at certain periods after freeze-dried bone implantation. The present results show that the healing process of freeze-dried bone implantation, even though autogenous bone was used, differed from that of fresh autogenous bone transplantation, and the differences are concerned not only with time sequences but also with qualitative changes. This suggests that the host would have some different responses to the freeze-dried autogenous bone from fresh materials.

Monoclonal antibody against histiocytosis X cells

Monoclonal antibody against histiocytosis X cells (HXCs) was established. The antigen was the cell membrane of HXCs from the submandibular lesion of a 63-year-old man who had been diagnosed as an adult type of histiocytosis X (HX) and whose HXCs had numerous Birbeck granules (BGs). The obtained monoclonal antibody, named MI1, reacted with the antigenic cell membrane of HXC. Immunoblotting showed that MI1 bound to the cell membrane of 28500 mw. MI1 also reacted with interdigitating reticulum cells (IDCs) in the tonsil and Langerhans cells (LCs) in the epidermis. MI1 reacted with the BGs which connected to the cell membrane, but not with those located near the nucleus.

Cytological mapping of Om mutants of Drosophila ananassae

Semidominant, optic morphology (Om) mutants in Drosophila ananassae have been genetically mapped to at least 25 loci throughout the genome (Hinton, 1984; 1988). Among them, four X-linked Om mutants were proved to be associated with the insertion of a transposable element, tom (Shrimpton et al., 1986; Tanda et al., 1988). In the present study, cytological mapping of autosomal Om mutants was carried out by in situ hybridization to polytene chromosomes using a cloned tom element as a probe. The cytological site for each autosomal Om mutant has been determined to a single band of the salivary gland chromosomes.

A case of hypothyroidism with simultaneous presence of stimulating type anti-thyrotropin (TSH) receptor antibodies and anti-thyroxine (T4) autoantibodies

We have examined a hypothyroid patient with stimulating type anti-thyrotropin (TSH) receptor antibodies and without blocking type anti-TSH receptor antibodies. Although she had high serum TSH (240 microU/ml) and low free triiodothyronine (FT3, 0.49 pg/ml) concentrations, which agree with physical findings of hypothyroidism, she had an unusually high free thyroxine (FT4) concentration (3.56 ng/dl). Incubation of her serum with 125I-T4, followed by precipitation with 12.5% polyethylene glycol (PEG) disclosed a higher binding of 125I-T4 (34.4%) than in normal controls, being 5-7%. In addition, binding of 125I-T4 to her serum gamma-globulin was completely displaced by the addition of unlabelled T4. From these results it was concluded that her serum contained anti-T4 autoantibodies. Treatment with synthetic T4 was begun and her thyroid function was monitored by sensitive TSH radioimmunoassay (RIA) and RIA of FT4 after PEG treatment. Since both sensitive TSH RIA and FT4 RIA results after PEG treatment give results concordant with the physical findings, it was concluded that both of the RIA results are useful for the evaluation of thyroid function in patients with thyroid hormone autoantibodies.

Absorption and metabolism of pyridoxamine in mice. II. Transformation of pyridoxamine to pyridoxal in intestinal tissues

The absorption of pyridoxamine from the intestine of the mouse was studied in whole animals. [3H]Pyridoxamine was orally administered and the distribution of isotope between the six recognized forms of vitamin B6 was determined in portal blood after the administration. When small doses (1.4 or 14 nmol) were administered, labeled pyridoxamine could hardly be found in the portal blood, although labeled pyridoxal and pyridoxal phosphate were found in the same blood. However, when a large amount (46 or 140 nmol) was given, a significant amount of labeled pyridoxamine was found with labeled pyridoxal and pyridoxal phosphate in the portal blood. These results suggest that a physiological dose of pyridoxamine is rapidly transformed to pyridoxal in the intestinal tissues and then released in the form of pyridoxal into the portal blood.

Post-transient ischemia increase in ubiquitin conjugates in the early reperfusion

Triton X-100-, digitonin- and urea-insoluble ubiquitin conjugates (UC) in the mitochondrial fractions of the gerbil cortex and hippocampus were analysed. In the cortex, following 5 min of forebrain ischemia, UC increased at 30 min of reperfusion and returned to the control level at 24 h. Although chronological changes in UC in the hippocampus were similar to the cortex, a more sustained increase of UC was observed. Immunoblot analysis showed that UC above 50 kDa increased in both regions. The results indicate that insoluble UC increase in the early recovery stage after ischemic neuronal damages.

Growth of a human yolk sac tumor cell line with yolk sac-derived functions in selenium-supplemented chemically defined synthetic medium

A human yolk sac tumor cell line, TG1, which was established from a testicular yolk sac tumor, was found to replicate continuously in a chemically defined medium supplemented with Na2SeO3 (ISRPMI). TG1 produced several plasma proteins and growth factors: albumin, alpha-fetoprotein (AFP), ferritin, carcinoembryonic antigen, beta-2-microglobulin, polyamine, neuron specific enolase, tissue polypeptide antigen, transferrin (Tf), epidermal growth factor, and platelet derived growth factor. By analysis of lentil lectin (LcHA)-affinity electrophoresis, to examine the microheterogeneity of carbohydrate chains of synthetic glycoproteins, TG1 cells cultured with ISRPMI produced only LcHA reactive Tf and AFP based on core fucose attached to asparagine-linked N-acetylglucosamine residues instead of LcHA-nonreactive Tf and AFP produced by TG1 cells cultured with fetal bovine serum (FBS)-containing medium. alpha 1-6 Fucosyltransferase activity was significantly greater in the TG1 cells cultured with ISRPMI (39.9 +/- 1.5 pmol.h-1.mg-1 protein) than cultured with FBS-containing media (18.2 +/- 1.2 pmol.h-1.mg-1 protein). These results have indicated that the selective increase of alpha 1-6 fucosyltransferase occurred when the cells were cultured with the FBS-free synthetic media.

[Outcome of patients with primary malignant lymphoma of the brain; relationship to the nucleolar organizer region]

Twelve cases of primary malignant lymphoma of the central nervous system had been treated since April, 1979 to August, 1990. Radiation therapy was completed in ten of them without adjuvant chemotherapy, and the other two patients expired before or during radiation therapy. In spite of good response to the radiation therapy, five of the ten patients died within 2 years. Three cases are alive after more than 5 years, and there has been no recurrence. In eight cases, the number of the argyrophilic proteins of the nucleolar organizer regions (AgNORs) was counted in the formalin-fixed paraffin embedded sections. In those cases with an AgNOR number of 4.0 or higher, prognosis was significantly worse than in the others. AgNOR number may be used as one of the reliable factors in the prognosis of primary malignant lymphoma of the central nervous system.

[Primary malignant lymphoma of the esophagus--a case report]

We report a rare case of primary malignant lymphoma of the esophagus without extraesophageal involvement. A 69-year-old woman was referred to our hospital because of dysphagia. Esophagogram revealed an irregularly marginal ulceration with stenosis at the abdominal esophagus. Endoscopic study showed an ulcerative lesion at the level of 30 cm from the incisor teeth. Esophagocardiectomy was performed. Resected specimen showed a shallow depressed ulceration, 6.5 x 6.0 cm in size, at the lower esophagus. Microscopic examination revealed malignant lymphoma of diffuse, large cell type. No evidence of involvement was found in the dissected lymph nodes and the bone marrow biopsy specimens. She has been well for 4 years and 6 months postoperatively.

[Effects of prostaglandin E1 and dibutyryl cyclic AMP on hemodynamics after cardiopulmonary bypass in valve replacement surgery]

In view of vasodilating action of prostaglandin E1 (PGE1) and dibutyryl cyclic AMP (DBcAMP) we investigated the effect of each agent on hemodynamics after weaning from cardiopulmonary bypass (CPB) comparing with the effect in control group. PGE1 and DBcAMP were administered to patients who underwent valve replacement surgery with continuous low dose infusion at an average rate of 0.026 micrograms.kg-1.min-1 and 7.25 micrograms.kg-1.min-1 respectively. Following result was obtained. In PGE1 administered group, a significant reduction in pulmonary vascular resistance (PVR) and a significant decrease in mean arterial pressure (MAP) were observed during CBP, while there were no significant differences in other parameters, such as platelet counts, differences between core and peripheral temperature (delta T), urine output, systemic vascular resistance (SVR), cardiac index (CI), right-to-left shunt (Qs/Qt), oxygen delivery (DO2) and oxygen consumption (VO2). However, CI and platelet counts tended to increase but delta T and SVR tended to decrease. In DBcAMP administered group, there were no significant differences in all parameters compared with those of control group, showing a tendency of less improvement in hemodynamics than in PGE1 group. We have shown that the use of PGE1 rather than DBcAMP as vasodilator agent seems advantageous during open-heart surgery in patients especially with severe pulmonary hypertension, but it tends to cause severe hypotension during CPB.

Nonrandom distribution of gp120 N-linked glycosylation sites important for infectivity of human immunodeficiency virus type 1

More than 20 consensus N-linked glycosylation sites occur in the gp120 coding sequence of most isolates of human immunodeficiency virus type 1. Based on the N-linked glycosylation pattern of a well-characterized recombinant gp120, it is likely that N-linked sugars are present at most, if not all, of the consensus glycosylation sites of the heavily glycosylated gp120. In this study, we evaluated the relative importance of each of the 24 N-linked glycosylation sites of gp120 in the molecular clone HXB2 to viral infectivity. The ability of HXB2-derived mutants, each having 1 of the 24 N-linked glycosylation sites mutated by site-directed mutagenesis, to infect CD4-positive SupT1 cells was compared with that of the wild-type virus. We found that most of the individual consensus N-linked glycosylation sites are dispensable for viral infectivity. The five consensus N-linked glycosylation sites that are likely to have important roles in infectivity are all located in the amino-terminal half of gp120, indicating that the N-linked glycosylation sites that are important for infectivity of human immunodeficiency virus type 1 are not randomly distributed in gp120. We predict that a partially glycosylated gp120 with most of the dispensable N-linked glycosylation sites removed may be a better vaccine candidate than the fully glycosylated gp120.

Developmental change of an enzyme activity oxidizing gamma-aminobutyraldehyde to gamma-aminobutyric acid in the chick embryonic brain

An enzyme activity oxidizing gamma-aminobutyraldehyde (ABAL) to GABA reflecting an alternative pathway for GABA synthesis was assayed in the developing chick embryonic brain and was compared with glutamate decarboxylase (GAD) activity. An enzyme activity oxidizing ABAL to GABA showed almost constant level during development in the chick embryonic brain, and was present at low levels compared with GAD activity. The results indicate that GABA synthesis via an alternative pathway is always much less than synthesis via the GAD-dependent pathway in the developing chick embryonic brain.