A dynamin-like protein in Arabidopsis thaliana is involved in biogenesis of thylakoid membranes

Dynamin, a GTP-binding protein found in rat brain, plays a role in endocytosis. Suborganellar fractionation studies of Arabidopsis leaf tissue revealed that a dynamin-like protein, ADL1, is localized in the thylakoid membranes of chloroplasts. This notion was supported further by in vivo targeting experiments using an ADL1-green fluorescent fusion protein and immunogold labeling with the anti-ADL1 antibody. Transgenic plants harboring various deletion mutant genes of ADL1 had a yellow leaf phenotype where the cells had very few chloroplasts. In addition, the remaining chloroplasts appeared morphologically not fully developed. The detailed structure of the chloroplasts revealed by electron microscopy showed a greatly reduced amount of thylakoid membranes. Also, the level of thylakoid membrane proteins such as the light-harvesting complex II and CP29 was greatly reduced in these transgenic plants. When we examined the expression of the ADL1 deletion mutant genes, these genes were highly expressed at the transcriptional level. However, the mutant ADL1s were not detectable at the protein level by Western blot analysis. Moreover, the endogenous ADL1 protein level was greatly reduced in these transgenic plants, probably due to a post-transcriptional silencing effect of the transgenes. We propose, therefore, that ADLl is involved in the biogenesis of thylakoid membranes.

Cre/loxP-mediated excision and amplification of large segments of the Escherichia coli genome

The isolation and amplification of large, predetermined segments of a genome from its host have been explored. The prototype of our approach was the excisional replication of some viruses such as the lambda-lysogen. Similar machinery was used to excise and amplify large genomic segments of Escherichia coli in its host. Two loxP sequences for a site-specific recombinase Cre, together with a conditional replication origin (pi-dependent gamma-ori), were inserted into the genome by homologous recombination at predetermined sites, 50-100 kb apart. Cre and pir200 which encodes the site-specific recombinase Cre and an ori-specific replication protein pi, respectively, were also introduced into the genome. The predetermined genomic segments flanked by the loxP sequences were excised and amplified upon induction of the cre and pir200 genes which were under the control of the tet promoter. This excised and amplified DNA could be easily purified as a large plasmid. This procedure can provide an alternative to conventional cloning methods by obtaining predetermined large genomic segments directly from the original organisms. In this study, using the Cre/loxP site-specific recombination and pi/gamma-ori replication system of plasmid R6K, a procedure was devised that could isolate a large segment of the E. coli genome and demonstrated the feasibility of the procedure by excising and amplifying the 50-kb trg-narZ and 100-kb trg-hipA regions of the E. coli W3110 genome.

Expression of HuD (a paraneoplastic encephalomyelitis antigen) mRNA in lung cancer

HuD, one of the Hu antigens (HuD and HuC), was recognized in the sera of small cell lung cancer (SCLC) patients with antibody-associated paraneoplastic encephalomyelitis/peripheral sensory neuropathy (PEM/PSN). Three forms of HuD mRNA, 197, 156, 110 nucleotides are made by alternative splicing at 868-909 residues and an additional 3'-splice site. To determine the diagnostic value of the HuD expression for small cell lung cancer, we examined 4 SCLC cell lines, 9 surgically resected SCLCs, and 12 surgically resected non-SCLCs using the reverse transcriptase-polymerase chain reaction with the HuD-specific primer pairs that spanned the putative alternative 3'-splicing site and direct DNA sequencing. None of the patients were associated with PEM/PSN. A single RNA transcript (156 nucleotides) among three forms (110, 156, 197 nucleotides) of the HuD gene was an alternatively spliced at 868-909 residues in SCLC cell lines. Expression of the HuD gene was stronger in three classic cell lines, but not in a variant cell line. Two of 9 SCLCs (22%) and 3 of 12 non-SCLCs (25%) expressed only the major RNA transcript (156 nucleotides) of the HuD gene, which was alternatively spliced in the same fashion as the cell line. These results revealed that no aberrant alternative splicing occurred in SCLC not associated with PEM/PSN and the expression of HuD gene was not specific for a particular histologic subtype of human lung cancer.

Synthesis and antibacterial activities of new 1 beta-methylcarbapenems having a 1,3-diazabicyclo[3.3.0]octan-2,4-dione moiety

The synthesis of a new series of 1 beta-methylcarbapenems having a 1,3-diazabicyclo[3.3.0]octane-2,4-dione moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bateria are determined and the effect of substituent on the bicyclic ring as well as stereoisomerism was investigated.

Oligomycin inhibits store-operated channels by a mechanism independent of its effects on mitochondrial ATP

Inhibitors of mitochondrial oxidative metabolism have been proposed to interfere with Ca2+ influx mediated by store-operated channels (SOC), secondary to their effects on ATP production. We assessed SOC activity by 45Ca2+ influx and fluorimetric measurements of free Ca2+ or Mn2+ quench in thapsigargin-treated Chinese hamster ovary cells and Jurkat T-cells, and additionally by electrophysiological measurements of the Ca2+-release-activated Ca2+ current (Icrac) in Jurkat T-cells. Various mitochondrial antagonists were confirmed to inhibit SOC. However, the following evidence supported the proposal that oligomycin, in particular, exerts an inhibitory effect on SOC in addition to its known actions on mitochondria and Na+-pump activity: (i) the concentrations of oligomycin required to inhibit SOC-mediated Ca2+ influx or Icrac (half-inhibitory concentration approximately 2 microM) were nearly 50-fold higher than the concentrations that blocked mitochondrial ATP production; (ii) the rank order of potency of oligomycins A, B and C for decreasing SOC-mediated Ca2+ influx or Icrac differed from that known for inhibition of mitochondrial function; (iii) oligomycin blocked Icrac under voltage clamp and with intracellular Na+ and K+ concentrations fixed by dialysis from the patch pipette, arguing that the effect was not secondary to membrane polarization or pump activity; and (iv) fixing the cytosolic ATP concentration by dialysis from the patch pipette attenuated rotenone- but not oligomycin-mediated inhibition of Icrac. Oligomycin also blocked volume-activated Cl- currents, a profile common to some other known blockers of SOC that are not known mitochondrial inhibitors. These findings raise the possibility that oligomycin interacts directly with SOC, and thus may extend the known pharmacological profile for this type of Ca2+-influx pathway.

Chondromalacia of the knee: evaluation with a fat-suppression three-dimensional SPGR imaging after intravenous contrast injection

Twenty-one MRI studies with a fat-suppression three-dimensional spoiled gradient-recalled echo in a steady state (3D SPGR) pulse sequence after intravenous contrast injection were evaluated to assess the accuracy in depicting chondromalacia of the knee. On the basis of MR images, chondromalacia and its grade were determined in each of five articular cartilage regions (total, 105 regions) and then the results were compared to arthroscopic findings. The sensitivity, specificity, and accuracy of MRI were 70%, 99%, and 93%, respectively. MR images depicted 7 of 11 lesions of arthroscopic grade 1 or 2 chondromalacia, and seven of nine lesions of arthroscopic grade 3 or 4 chondromalacia. The cartilage abnormalities in all cases appeared as focal lesions with high signal intensity. Intravenous contrast-injection, fat-suppression 3D SPGR imaging showed high specificity in excluding cartilage abnormalities and may be considered as an alternative to intra-articular MR arthrography when chondromalacia is suspected.

Synthesis and antibacterial activity of 1-beta-methylcarbapenem having a 1,3-diazabicyclo[3.3.0]octan-4-one moiety

The synthesis of new series of 1-beta-methylcarbapenems having a 1,3-diazabicyclo[3,3,0]octan-4-one moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram negative bacteria are reported and the effect of the substituent on the bicyclic ring was investigated and was in agreement with findings from our previous studies.

[Mite infestation rate of pet dogs with ear dermatoses]

This study aimed to investigate the incidence of the canine ear dermatoses caused by mites and the relativity of the causative mites of canine dermatoses to the pruritic dermatoses of the families possessing the pet dogs. Total 970 samples were collected from the lesional hairs and scales of the ear of pet dogs referred to Chung-Woon animal clinic in Seoul from January, 1990 to December, 1995. The mites were collected from the samples by means of the washing method. Presence of pruritic dermatoses in the families possessing the pet dog was evaluated. Among 2,147 mites collected from 970 samples, 2,117 specimens were Octodectes cynotis and others were Sarcoptes canis (30 mites). O. cynotis were found in 382 samples out of total 970 samples (39.4%) and S. canis were found in 3 samples (0.3%). Although two families out of 382 families that possessed the diseased pet dog by O. cynotis had the family histories of pruritic dermatoses, their pruritic dermatoses were not related to the infestation by O. cynotis. In conclusion, O. cynotis, the most common canine mite producing pruritic ear dermatoses, does not cause pruritic dermatoses in man.

Long-term administration of acipimox potentiates growth hormone response to growth hormone-releasing hormone by decreasing serum free fatty acid in obesity

Obesity is associated with an impairment of normal growth hormone (GH) secretion and blunted responses to all stimuli. A high plasma free fatty acid (FFA) level is frequently observed in obesity. FFA participates in the regulation of pituitary GH secretion. To determine whether the derangement of GH secretion in obesity is associated with high plasma FFA levels, tests with GH-releasing hormone (GHRH) and acipimox (ACX), an antilipolytic agent able to decrease FFA, were undertaken in six obese subjects and seven normal control subjects. In addition, the effect of prolonged suppression of FFA level on GH response to GHRH after administration of ACX for 1 month was also examined in each of the obese subjects. The GH response in obese subjects (median, 9.1 microg/L) to GHRH (1-29) (1 microg/kg intravenously [IV]) was significantly blunted as compared with normal control subjects (23.5 microg / L, P < .05). Basal FFA levels were higher in obese subjects (855.2 microEq / L than in normal control subjects (514.6 microEq / L, P < .05). One-dose ACX (500 mg) decreased FFA levels in both obese and normal subjects: the lowest FFA levels in obese subjects (158.3 microEq/L 2 to 2.5 hours after ACX were similar to those of normal control subjects (108.7 microEq/L). One-dose ACX potentiated GHRH-stimulated GH response in both obese and normal subjects. GH responses potentiated by ACX in obese subjects (27.1 microg/L) were similar to GH responses to GHRH in normal control subjects, but lower than in normal subjects treated with ACX plus GHRH (58.5 microg / L, P < .05). Thereafter, all of the obese subjects were treated with ACX for 1 month, after which the ACX plus GHRH tests were repeated. After 1 month of acipimox administration in the obese subjects, GH responses (38.8 microg/L) were significantly higher than those of obese subjects treated with GHRH and one-dose ACX plus GHRH (P < .05). They were similar to GH responses of normal control subjects receiving the one-dose ACX plus GHRH test. In conclusion, in obesity the prolonged suppression of FFA levels induced by long-term administration of ACX potentiated somatotrope responsiveness, likely acting at the pituitary level, suggesting that the duration of FFA suppression had an important relation to the magnitude of GH response.

Loss of heterozygosity of multiple tumor suppressor genes in human gastric cancers by polymerase chain reaction

Loss of heterozygosity (LOH) occurring on various chromosomes has been described in the majority of human tumors and its targets are believed to be tumor suppressor genes. Although allelic deletion of the p53 gene (over 60%) has been frequently observed in gastric cancer, as well as in other human malignancies, LOH of other tumor suppressor genes is still discrepant in gastric cancer. To our knowledge, simultaneous analysis of LOH using PCR in adenomatous polyposis coli (APC), deleted in colon cancer (DCC), and retinoblastoma susceptibility (Rb) genes has not yet been reported in sporadic gastric cancer. We examined 21 advanced gastric cancers (12 intestinal type and 9 diffuse type) for LOH at the APC, DCC, and Rb loci using PCR. Inclusion of these tumor suppressor genes in the allelic deletions was directly ascertained by performing PCR at polymorphic sites within the genes. LOH occurred in 30% of informative cases at APC, in 27% of informative cases at DCC, and in 30% of informative cases at Rb. Thirty-three percent of tumors informative at all loci (fully informative) lost heterozygosity at all three loci. There were no significant differences among histologic types in the prevalence of LOH at any locus and no correlations between losses involving APC, DCC, and Rb genes. These data suggest that inactivation of APC, DCC, and Rb is involved in the development and progression of some human gastric cancers regardless of histologic type.

MR appearance of distal femoral cortical irregularity (cortical desmoid)

PURPOSE

Our goal was to describe the MR appearance of distal femoral cortical irregularity (DFCI).

METHOD

With plain radiographs and MR images of 100 knees, the presence of DFCIs was determined, and the shapes of DFCIs were classified into three subgroups: concave, convex, and divergent cortical shapes. Radiographic and MR shapes of DFCIs were compared.

RESULTS

DFCIs were shown in various shapes on both the radiographs and the MR images. Forty-four DFCIs were found both on radiograph and by MR image. An additional 14 DFCIs were identifiable only on MR images. However, the majority of DFCIs showed an association between radiographic and MR shapes. MRI revealed that all 58 DFCIs were located at the attachment site of the medial gastrocnemius muscle. DFCIs were enhanced in three of the four patients who underwent postcontrast MR study.

CONCLUSION

A good understanding of radiographic and MR findings of the DFCI may be of great help in the differential diagnosis of distal femoral lesions.

MR imaging of tuberculous arthritis: clinical and experimental studies

Signal-intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2-weighted images, while they showed heterogeneously intermediate signal intensity on T1-weighted images. As T2-weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1-weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra-articular lesions with low or intermediate signal intensity are found on T2-weighted images.

Arthroscopy of symptomatic total knee replacements

Between December 1983 and August 1992, 21 knees in 19 patients with symptomatic total knee replacements were arthroscopically diagnosed. The average time between total knee replacement and arthroscopy was 20 months (ranging from 4 to 84 months). All patients were primary total knee replacements. Metal bars, 5 and 8 mm in diameter and 40 cm in length, were made for arthroscopic treatment of fibroarthrosis. Thirteen knees of 11 patients with a diagnosis of arthrofibrosis had an average improvement of 42 degrees arc of motion 1 year after arthroscopic surgery. Three knees with an average of 15 degrees increase of motion were determined to be failures. Another two patients had arthroscopic resection of fibrous bands with complete relief of patella pain. Among six patients who had revision of total knee replacements after arthroscopic diagnosis, four had wear in the metal backed patella components, and two had wear in the tibial insert and loosening of cementless patella component. An early diagnosis of implant failure under arthroscopic control was made, which easily allowed revision of the metal-backed patellar button before the development of metallosis and massive osteolysis caused by the marked wear of polyethylene. With the use of our specially made metal bars for treating arthrofibrosis, we could release the adhesion more easily and avoid damage of valuable arthroscopic instruments.

Depletion of hepatic 3'-phosphoadenosine 5'-phosphosulfate (PAPS) and sulfate in rats by xenobiotics that are sulfated

Sulfation is considered a high-affinity but low-capacity conjugation mechanism that is limited by the availability of 3'-phosphoadenosine 5'-phosphosulfate (PAPS), the cosubstrate for sulfation. Salicylamide, phenol and 1-naphthol are all known substrates for the sulfation reaction. This study was conducted to determine whether the xenobiotics that are sulfated when administered to rats will lower hepatic PAPS and its precursor, sulfate. Urinary sulfate excretion was reduced 85% to 95% by these compounds. Hepatic PAPS was reduced 73%, 39%, and 87% by salicylamide, phenol and naphthol, respectively, 2 hr after administration of 2 mmol/kg. These compounds also decreased serum sulfate concentrations by 45% to 86% and lowered hepatic sulfate concentrations. In summary, these studies demonstrate that salicylamide, phenol and 1-naphthol lower hepatic PAPS and sulfate concentrations, as well as serum sulfate concentrations. These findings imply that increased sulfation, as a result of the sulfation of xenobiotics, results in depletion of hepatic PAPS concentrations, possibly because the utilization of PAPS by the sulfotransferases exceeds its generation via sulfate activation. Thus the capacity-limited sulfation of high dosages of xenobiotics appears to be due to the reduced availability of hepatic PAPS, which in turn is limited by the availability of sulfate.

Acipimox potentiates growth hormone response to growth hormone-releasing hormone by decreasing serum free fatty acid levels in hyperthyroidism

Hyperthyroidism is associated with an impairment of growth hormone (GH) responses to secretagogues. The aim of this study was to evaluate the effect of acipimox, an antilipolytic agent able to decrease free fatty acids (FFA), on GH response to GH-releasing hormone (GHRH) in hyperthyroid and normal control subjects. We studied six men with hyperthyroidism; seven normal men served as control subjects. Each subject underwent treatment with (1) 2 tablets of placebo orally or (2) 500 mg acipimox orally, 120 minutes before intravenous (IV) injection of 1 microgram/kg GHRH-(1-29)NH2. GH response to GHRH in hyperthyroid patients was markedly reduced; the mean peak GH response (9.6 +/- 1.0 microgram/L) and the area under the GH response curve (12.9 +/- 1.3 micrograms/L x 2 h) were lower than those of control subjects (25.7 +/- 1.8 micrograms/L, P < .05; 28.7 +/- 2.1 micrograms/L x 2 h, P < .05). Hyperthyroid patients had higher baseline levels of plasma FFA than control subjects (998.0 +/- 38.9 v 498.0 +/- 36.0 muEq/L, P < .01). Acipimox decreased FFA levels in both hyperthyroid and control subjects; the lowest FFA levels of hyperthyroid subjects induced by acipimox were similar to those of control subjects. After acipimox pretreatment, GH responses to GHRH increased significantly (P < .05); the mean peak plasma GH level (25.9 +/- 4.6 micrograms/L) was similar to the peak GH levels of control subjects during the GHRH test, and the area under the GH response curve (41.1 +/- 6.7 micrograms/L x 2 h) was even higher than that of control subjects with the GHRH test.(ABSTRACT TRUNCATED AT 250 WORDS)

Acipimox potentiates growth hormone (GH) response to GH-releasing hormone with or without pyridostigmine by lowering serum free fatty acid in normal and obese subjects

Obesity is associated with an impairment of normal GH secretion and blunted responses to all stimuli. Recent reports suggest that increased somatostatinergic activity is the basis for the GH derangement of obesity. However, the basic mechanism of this alteration is still being debated. The high plasma free fatty acid (FFA) is frequently observed in obesity. FFA participates in the regulation of pituitary GH secretion. To determine whether the derangement of GH secretion in obesity is associated with high plasma FFA levels, several tests with GHRH with or without pyridostigmine (PYR) and acipimox (ACX), antilipolytic agents able to decrease FFA, were undertaken in six obese and seven normal control subjects. In obese subjects, the GH response (mean peak +/- SEM: 8.9 +/- 1.1 ug/L) to GHRH-(1-29) (1 ug/kg, i.v.) was significantly blunted when compared with the response in normal control subjects (25.7 +/- 1.8 ug/L; P < 0.05). After PYR (120 mg), the response to GHRH was enhanced in the obese subjects (21.4 +/- 4.9 ug/L; P < 0.05) and was similar to that of the controls with GHRH only, but remained significantly reduced compared with controls treated with PYR plus GHRH (43.2 +/- 6.0 ug/L; P < 0.05). Basal FFA levels were higher than those of normal controls (P < 0.05). ACX (500 mg) decreased FFA levels in both obese and normal subjects; the lowest FFA levels of obese subjects at 15 min were similar to those of normal controls. ACX also potentiated GHRH-stimulated GH response in both obese and normal subjects. The GH responses potentiated by ACX in obesity (22.7 +/- 5.5 ug/L) were similar to those of PYR plus GHRH in obese subjects and GHRH in normal controls, but they were lower than those of control treated with ACX plus GHRH (50.8 +/- 6.7 ug/L; P < 0.05). After the combined pretreatment with ACX and PYR, GH responses in obesity (44.1 +/- 6.0 ug/L) were significantly higher than those in GHRH test, PYR plus GHRH, and ACX plus GHRH in obese subjects (P < 0.05), and they were similar to PYR plus GHRH or ACX plus GHRH in normal controls. However their enhanced GH responses were reduced compared with the control with ACX plus PYR plus GHRH (64.9 +/- 4.5 ug/L; P < 0.05). Our results are in agreement with the hypothalamic hypothesis: an increase in somatostatinergic tone is responsible for the blunted GH response to GHRH in obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo modification of 3'-phosphoadenosine 5'-phosphosulfate and sulfate by infusion of sodium sulfate, cysteine, and methionine

The importance of tissue sulfate concentrations in regulating 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthesis is not known. Therefore, this study was conducted to determine the influence of increased availability of inorganic sulfate on steady-state PAPS concentrations in various tissues. To increase tissue sulfate concentrations, 2-16 mmol/kg of sodium sulfate and sulfur-containing amino acids (cysteine or methionine) were infused intravenously for 2 hr into pentobarbital-anesthetized rats. Serial blood samples were taken during the infusion and analyzed for sulfate concentrations. After 2 hr of infusion, liver, kidney, and brain were removed for quantification of tissue PAPS and sulfate concentrations. Infusion of sodium sulfate, cysteine, and methionine increased serum and tissue sulfate concentrations in a dose- and time-dependent manner. Serum sulfate concentrations increased from 0.8 to 14 mM during the infusion of sodium sulfate, whereas infusions of cysteine and methionine increased serum sulfate concentrations to 4.8 and 2.0 mM, respectively. Tissue sulfate concentrations also increased during sulfate infusion. Liver sulfate concentration increased from 0.8 to 4.8 mM, kidney concentration increased from 0.6 to 31 mM, and brain concentration increased from 0.1 to 0.6 mM. Similar to the serum sulfate concentrations, sulfate infusion was the most effective in increasing tissue sulfate concentrations, cysteine was intermediate, and methionine the least effective. Although sulfate concentrations in liver, kidney, and brain increased 6-, 50-, and 6-fold by infusing sulfate, respectively; tissue PAPS levels were not altered markedly. Hepatic PAPS concentrations increased significantly (30-35%) only when infused with the higher doses (8 or 16 mmol/kg/2 hr) of sodium sulfate.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased calcium stores in platelets from African Americans

Differences in cation transport have been observed between African Americans and whites. These differences may underlie the increased predisposition of African Americans to essential hypertension. To further explore these racial differences, we used platelets as a cellular model for calcium regulation. We measured 45Ca fluxes in platelets from 21 African American and 25 white men. Additionally, using fura 2, we measured cytosolic free calcium levels in resting platelets and platelets treated with ouabain and thrombin. Platelet 45Ca uptake was described by two exchangeable pools: a small, rapidly exchangeable pool and a larger, slowly exchangeable pool. Both pools were larger in platelets from African Americans than from whites (263 versus 185 pmol per 1 x 10(8) platelets for the rapidly exchangeable pool, P < .05; 744 versus 532 pmol per 1 x 10(8) platelets for the slowly exchangeable pool, P < .01). 45Ca washout was described by a rapidly exchangeable pool and a static pool. The former was also higher in platelets from African Americans than from whites (246 versus 202 pmol per 1 x 10(8) platelets, P < .01). The cytosolic free calcium concentrations in resting platelets were lower in African Americans than in whites. After treatment with ouabain and thrombin, the sustained posttransient levels of cytosolic free calcium increased to a greater extent in platelets from African Americans (46.7 nmol/L) than from whites (34.5 nmol/L, P = .033). Platelets from African Americans demonstrate higher intracellular calcium stores than platelets from whites. This racial difference could explain the sensitivity of African Americans to vasoactive agents acting through calcium mobilization from intracellular stores and cytosolic calcium.

Differential expression of leukocyte common antigen in human fetal lymphoid organs

To investigate the differential expression of various types of leukocyte common antigen (LCA) isoforms during development, we analyzed human fetal lymphoid organs, including the thymus, liver, spleen, and bone marrow from 14 weeks to 29 weeks of gestational age by immunohistochemical and flow cytometric methods. In fetal thymus, over 90% of thymocytes throughout the entire fetal life expressed CD45RO and CD45RB, while CD45RA was expressed only in less than 5% of thymocytes. This expression pattern of LCA isoforms was established by a gestational age of 14 weeks or earlier, and persisted throughout the fetal period. The tissue distribution was different from each isoform; CD45RO-positive thymocytes were found in both the cortex and medulla at the 14th week with low intensity, but was localized in the cortex with increasing fetal age. CD45RB-positive thymocytes distributed mainly in the medulla from early gestational age. Among extrathymic lymphoid organs, a small portion of lymphoid cells expressing leukocyte common antigens appeared first in the liver at 10-12 weeks of gestational age and was followed by a small number in the spleen and bone marrow by 13-15 weeks. All lymphoid cells in these extrathymic lymphoid organs at this stage were CD19+ B cells. The number of these CD19+ cells increased abruptly during the early period of mid-gestational age. The pattern of tissue distribution of each LCA isoform in the fetal liver and spleen correlated well with the patterns of quantitative analysis by flow cytometry. In summary we found that different LCA isoforms expressed in cell-type-specific pattern and showed different tissue distribution during the period of fetal development, and that LCA was the earliest antigen expressed by lymphocytes in the thymus and extrathymic lymphoid organs in our series.

Glucocorticoids regulate Na+/H+ exchange expression and activity in region- and tissue-specific manner

Na+/H+ exchangers (NHEs) are integral membrane proteins that exchange Na+ for H+ across membranes. Four isoforms have been cloned (NHE-1-4). NHE-3 localizes to the apical domain, and its expression is increased in dexamethasone-treated rats by Northern analysis. This stimulatory effect on expression is region and tissue specific, being present in ileum and proximal colon, but not in jejunum, distal colon, or kidney. The increase in transcript expression in ileum correlates with an increase in protein expression by immunoblotting. Changes in apical Na+/H+ exchange activity, as measured by 22Na uptake into brush-border membrane vesicles, correlate with expression differences, with significant increases observed in ileum and proximal colon. In situ hybridization showed NHE-3 mRNA only in villus and absorptive cells of control rats, the pattern not being altered by dexamethasone treatment. This suggests that dexamethasone does not increase expression by inducing crypt cells to express NHE-3 prematurely. We conclude that glucocorticoids selectively increase intestinal NHE-3 activity in a region-specific manner and that this effect also appears to be tissue specific.

Inhibition of Ca2+ entry by Ca2+ overloading of intracellular Ca2+ stores in human platelets

1. This study examined the effect of overloading human platelet intracellular Ca2+ stores on the rate of agonist-evoked external Ca2+ entry. To overload the Ca2+ stores (presumably dense tubules), external Na(+)-dependent Ca2+ efflux via Na(+)-Ca2+ exchange was inhibited by pretreating the cells with ouabain or Na(+)-free medium. Ca2+ regulation was then examined after exposure to thrombin, ADP and thapsigargin. Cytosolic free Ca2+ levels were monitored using the fluorescent probe fura-2 and external Ca2+ influx was assessed by the rates of extracellular Mn2+ or 45Ca2+ uptake. 2. Both ouabain and Na(+)-free pretreatments caused a slight increase in the resting cytosolic free Ca2+. 3. In 1 mM Ca(2+)-containing medium, Ca(2+)-overloaded platelets showed similar thrombin-evoked cytosolic free Ca2+ responses to those of control platelets. However, in Ca(2+)-free medium, they showed substantially greater thrombin-evoked cytosolic free Ca2+ responses than control platelets. Moreover, increased thrombin-evoked Ca2+ mobilization from Ca2+ storage sites was accompanied by a diminished rate of thrombin-evoked external Ca2+ entry. 4. Similar reductions in the rate of external Ca2+ entry were observed after treatment with ADP and thapsigargin. 5. Protein kinase C inhibitors (calphostin C and staurosporine) failed to reverse the effect of ouabain pretreatment on thrombin-induced changes in the cytosolic free Ca2+ response. 6. Inositol 1,4,5-trisphosphate profiles in ouabain-treated and non-treated platelets were not significantly different. 7. These data indicate that increased Ca2+ in the dense tubules is associated with diminished agonist-evoked external Ca2+ influx.

Obstructive jaundice due to compression of the common hepatic duct by right hepatic artery--a case associated with the absence of the lateral segment of the left hepatic lobe

Various benign and malignant conditions can cause biliary obstruction. We present a rare case of obstructive jaundice due to the compression of the common hepatic duct by the anteriorly overriding right hepatic artery. This case was also associated with the absence of the lateral segment of the left hepatic lobe. The patient was a 39 year-old housewife with a 4-day history of jaundice and occasional febrile sensation. An abdominal computed tomography showed absence of the lateral segment of the left hepatic lobe and a percutaneous transhepatic cholangiography showed a band-like filling defect of 2 mm width at the level of the upper common hepatic duct. The anteriorly overriding right hepatic artery compressing the common hepatic duct and the absence of the lateral segment of the left hepatic lobe were confirmed by operation.

The luminance-response function of the dark-adapted rabbit electroretinogram

The Naka-Rushton equation of the form, R = Rmax I(n)/(I(n)+Kn), has been used to describe the b-wave luminance-response function of the scotopic electroretinogram. Rmax is the asymptotic value of the b-wave amplitude as a function of stimulus luminance I, K is the luminance that produces a b-wave amplitude that is one-half Rmax, and n is a dimensionless constant that controls the slope of the function. These three parameters are often used in research laboratories, since it can show selective changes in each parameter. The present study describes these parameters (Rmax = 354 +/- 28 uV, n = 0.80 +/- 0.06, log K = -2.26 +/- 0.15 log cd. sec/m2) and the values obtained from the derivative analysis of Naka-Rushton equation (Anastasi et al) in 20 normal pigmented rabbit eyes. However, Naka-Rushton equation accurately describes the function only at low to moderate flash luminances. At high flash luminances, a second amplitude increase appears in the function.

Blood pressure inversely correlates with thrombin-evoked calcium rise in platelets

Earlier investigations showed a positive correlation between basal cytosolic free calcium in human platelets and blood pressure; however, recent studies have failed to show this relation. We undertook the present work to examine which platelet cytosolic calcium parameters (namely, cytosolic calcium in resting or stimulated states in calcium-containing and calcium-free media) present the least variability and best correlation with blood pressure. We studied 17 healthy white men on three different occasions separated by 1- and 4-week intervals. Their manual and ambulatory automated 24-hour blood pressure measurements were correlated with cytosolic calcium in resting and stimulated (thrombin-treated) fura 2-loaded platelets. The following cytosolic calcium parameters were measured in 1 mmol/L calcium and calcium-free media: basal cytosolic calcium, peak thrombin-evoked cytosolic calcium, and post-transient cytosolic calcium 5 minutes after thrombin treatment. The highest and lowest coefficients of variation were respectively shown by the basal cytosolic calcium (22.8%) and peak thrombin-evoked cytosolic calcium (10.1%) in calcium medium. Basal cytosolic calcium did not correlate with any of the blood pressure parameters. Of the cytosolic calcium parameters, peak thrombin-evoked cytosolic calcium in calcium medium demonstrated consistent (negative) correlations with blood pressure, with better correlations shown with diastolic than systolic blood pressure of both automated and manual blood pressure readings. Peak thrombin-evoked cytosolic calcium in calcium medium showed similar correlations with nighttime and daytime automated blood pressure measurements. There were no correlations between peak thrombin-evoked cytosolic calcium in calcium-free medium and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in platelet calcium regulation between African Americans and Caucasians: implications for the predisposition of African Americans to essential hypertension

OBJECTIVE

To study differences in cytosolic free calcium regulation between African Americans and Caucasians, using platelets as a model for studying cellular physiology.

DESIGN

Platelet calcium regulation in apparently healthy African American and Caucasian males was examined.

METHODS

Using fura-2, calcium influx and cytosolic calcium extrusion were monitored after treatment with thapsigargin, an inhibitor of the Ca-ATPase in the dense tubular membrane system.

RESULTS

Compared with Caucasians, platelets from African Americans demonstrated a higher calcium influx into the cytosol (from the external medium and dense tubular membrane system), as well as enhanced calcium extrusion from the cytosol.

CONCLUSIONS

Such findings indicate that platelets from African Americans have increased intracellular calcium stores or increased cellular calcium turnover, or both. If these racial differences involve other cells, such as vascular smooth muscle cells, they could underlie the predisposition of African Americans to essential hypertension.

Analysis of regional differences of p53 mutation in advanced gastric carcinoma: relation to heterogeneous differentiation and invasiveness

In order to examine the correlation of p53 mutation with heterogeneous histological differentiation and invasiveness of gastric carcinoma, we analyzed 46 areas (three to six per case) that were different histologically and anatomically in 12 advanced gastric carcinomas, shown previously to be positive for p53 mutation, using immunohistochemical, polymerase chain reaction-single strand conformation polymorphism, and direct DNA sequencing analyses. DNA derived from different sites in nine cases had the same pattern of p53 mutation, even in cases manifesting heterogeneous histology within a single tumor. Site difference of the p53 mutation was found in three cases: two showed no mutation in superficial tumor areas but presence of mutation in deep-infiltrating areas. In contrast, one case contained a mutation in the superficial area but not in the deep-infiltrating area. These results suggest that in most cases, tumor cells forming a single advanced gastric carcinoma, even though they may present a heterogeneous histology and deep invasion, seem to be derived from the same cellular clone.

Primary choriocarcinoma of the urinary bladder--a case report

We report a primary choriocarcinoma of the urinary bladder in a 63-year-old man who presented with painless hematuria. He was diagnosed as having an invasive carcinoma and underwent a total cystectomy. The tumor was diffusely hemorrhagic and occupied the dome of the bladder. Histologically, it consisted of cyto-and syncytiotrophoblasts with extensive hemorrhage. No coexisting transitional cell carcinoma component was present. By immunohistochemistry, the tumor expressed beta-hCG and low-molecular weight cytokeratin intensely while it was negative for CEA or EMA. The post-cystectomy serum beta-hCG was 237mlU/ml, and decreased later. The pertinent literature is reviewed and diagnostic criteria are discussed.

Platelet sodium-hydrogen antiport in obese and diabetic black women

In this investigation we correlated platelet Na-H antiport parameters with blood pressure and serum lipids in a sample population of non-insulin-dependent diabetic obese, nondiabetic obese, and nondiabetic nonobese black women. Parameters of the Na-H antiport were examined in aspirin-treated platelets. These parameters were not altered in resting or in thrombin-stimulated platelets of diabetic patients. The activity index of platelet Na-H antiport after thrombin stimulation was positively correlated with the blood pressure (systolic blood pressure, r = 0.5320 and p = 0.0001; diastolic blood pressure, r = 0.5123 and p = 0.0017). Lower high density lipoprotein cholesterol levels were associated with an alkaline shift in the cytosolic pH set point for activation of the Na-H antiport. Highly significant correlations were also observed between the total cholesterol/high density lipoprotein cholesterol ratio and the cytosolic pH set point for activation of the Na-H antiport. These correlations were independent of diabetes or the body mass index. Together, these observations indicate that parameters of platelet Na-H antiport are altered with an increase in blood pressure and a decrease in serum high density lipoprotein cholesterol.