Linkage and mutation analysis in two Taiwanese families with long QT syndrome

Long QT syndrome (LQT) is a cardiovascular disorder causing syncope and sudden death from arrhythmias. Mutations in KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A genes encoding cardiac potassium and sodium ion channels cause LQT. Two Taiwanese LQT families were screened for mutations in these ion channel genes. In family H87, the diagnosis was made in the 25-year-old female proband and six family members based on recurrent syncope and/or a prolonged QT interval. Genotyping revealed a novel nonsense mutation, R744X (C to T transition in codon 744), in the KCNH2 potassium channel gene, resulting in truncation of the putative cyclic nucleotide-binding domain and C-terminal region of the HERG K(+)-channel in all affected family members. The mutation was confirmed by DdeI endonuclease digestion of the DNA from each family member. The 26-year-old female proband in family L89 developed repeated syncope with QTc of 0.61 seconds. After linkage and mutation analysis, the syndrome in this family was associated with a novel KCNQ1 missense mutation, T309I, causing the substitution of a threonine residue at position 309, in the pore region of the KvLQT1 K(+)-channel, with an isoleucine. By Tsp45I restriction analysis, the mutation was noted in the proband and the proband's asymptomatic brother, but was not detected in 100 unrelated normal individuals. Identification of a mutation has clinical implications for presymptomatic diagnosis and therapy.

Monitoring patient satisfaction with university dental services under two fee-paying systems

AIMS

The aim of this survey was to study patients' satisfaction with the dental service of a university in Hong Kong under a recently introduced item-based fee-paying system and reasons for non-attendance at the clinic; and to compare results of the present survey with that of a similar survey of the same dental service under a time-based fee-paying system in 1996.

METHOD

A modified Dental Satisfaction Questionnaire was distributed to a random sample of students (n=194) in their lecture rooms and they were asked to complete the questionnaire on the spot. The same questionnaire was sent to a random sample of staff and their spouses (n=207) by mail.

RESULTS

Dental Satisfaction Index (DSI) scores calculated from the returned questionnaires were 66 for students and 70 for staff and their spouses. Compared to the scores in 1996, there was no significant difference for that of the students (DSI=65 in 1996) but there was a significant improvement in that of the staff and their spouses (DSI=66 in 1996). Moreover, in the present survey, "busy/no time" and "no perceived dental problem" were the major reasons for non-attendance, in contrast to "long waiting time for an appointment" in the 1996 survey, were the major reasons for non-attendance.

CONCLUSION

The recent attempts by the University Dental Clinic to shorten patient waiting time and the change in fee-paying system might have improved the patients' satisfaction with the service.

Large drug resistance virulence plasmids of clinical isolates of Salmonella enterica serovar Choleraesuis

Salmonella enterica serovar Choleraesuis generally causes systemic human salmonellosis without diarrhea, and therefore, antimicrobial treatment is essential for such patients. The drug resistance information on this organism is thus of high value. Serovar Choleraesuis usually harbors a virulence plasmid (pSCV) of 50 kb in size. Of the 16 clinical isolates identified to be serovar Choleraesuis, all except one harbored a pSCV and seven of them carried a pSCV of more than 125 kb in size. A pSCV was defined as a plasmid carrying spvC and characteristic deletions detected by PCR and by DNA-DNA hybridization (for the former criterion). The results of PCR, restriction fragment profiles, and Southern DNA-DNA hybridizations of the profiles all indicated that such larger pSCVs were derived from the 50-kb plasmid recombined with non-pSCVs found in some clinical isolates. Fifteen of the 17 strains, including a laboratory strain, were then tested for drug resistance against 16 antibiotics with E-test and the dilution method. The laboratory strain, which harbored a 50-kb pSCV and a 6-kb non-pSCV, was resistant only to sulfonamides (SUL), and its resistance gene, sulII, checked with PCR and DNA-DNA hybridization, was located on the 6-kb non-pSCV. All 14 clinical strains were resistant to multiple drugs. Of the 14, 7 were resistant to SUL, and the resistance gene was located on a plasmid. The sulII gene, but not bla(TEM-1), was carried only on the 6-kb non-pSCV. Of the remaining six large plasmids, three of 90 kb, two of 136 kb, and one of 140 kb, the last three were pSCVs and carried the other SUL gene (sulI) and the bla(TEM-1) gene. The six strains were also resistant to trimethoprim-sulfamethoxazole. None of the 50-kb pSCVs carried resistance genes. These drug resistance genes on the large pSCVs were apparently also acquired through recombination.

Prognostic factors of hyperglycemic hyperosmolar nonketotic state

BACKGROUND

To delineate the prognostic factors of patients suffering from hyperglycemic hyperosmolar nonketotic state (HHNK) in Taiwan.

METHODS

We reviewed the charts of patients who had been admitted to the Division of Endocrinology and Metabolism of Kaohsiung Veterans General Hospital from 1992 to 1998 due to HHNK. General and clinical data were collected. The influential factors for prognosis were determined.

RESULTS

One hundred and nineteen patients fulfilling the criteria of HHNK were included in our study. The mean age was 67.8 +/- 11.7 years with male predominance. Twenty-nine patients died which produced a fatality rate of 24.4%. Eighty-six (72.3%) cases occurred in patients with known diabetic history, while another thirty-three (27.7%) occurred in patients with no diabetic history. Most patients received oral antidiabetic drugs before HHNK episodes. The patients who died had shorter length of inpatient stay than did survivors. The leading precipitating factor was infection (57.1%), followed by poor compliance of medication (21.0%) and undiagnosed diabetes (10.9%). Fifty patients (42%) had a history of stroke. The risk factors for death included precipitation of HHNK by infection and low Glasgow coma scale (GCS) on admission. Old age itself did not contribute to death. Severity of hyperglycemia or hyperosmolarity was also not an important prognostic factor. Multiple logistic regression revealed that low GCS on admission was the most influential factor of leading to death. Most of the patients who died did so due to underlying precipitating factors.

CONCLUSIONS

Neither age nor osmolarity, but underlying precipitating factors and state of consciousness were the most influential factors affecting the prognosis of HHNK.

1.55-mum and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector

We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum . The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum . The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum , 10-mW laser diode. The corresponding quantum efficiency is 14.4%.

Molecular cloning, modeling, and localization of rat type 10 17beta-hydroxysteroid dehydrogenase

Rat and mouse complementary DNAs of type 10 17beta-hydroxysteroid dehydrogenase were cloned and sequenced. The mouse cDNA clone's sequence corrected the previously published nucleotide and amino acid sequence of mouse endoplasmic reticulum-associated beta-amyloid-binding protein. A subunit of the rat enzyme consists of 261 amino acid residues with a calculated molecular mass of 27250 Da. Compared with its human counterpart, rat 17betaHSD type 10 shows 88% identity. Mouse 17betaHSD type 10 is composed of 261 amino acid residues with a calculated molecular mass of 27274 Da. There is 95% identity between the two rodent enzymes. A stereostructure model of rat 17betaHSD type 10 was constructed based on its amino acid sequence. Similar to human type 10 17betaHSD, the rodent enzymes also displayed relatively higher 3alphaHSD activity than 17betaHSD activity. Intracellular localization of rat 17betaHSD type 10 has been determined by subcellular fractionation and confocal microscopy studies. The results unequivocally establish that this is a nuclear gene-encoded mitochondrial enzyme, and that this 17betaHSD is not associated with the endoplasmic reticulum. The unique location distinguishes type 10 from other types of 17beta-hydroxysteroid dehydrogenases.

Treatment of early childhood caries: a review and case report

Caries in infants and young children long has been recognized as a clinical entity and described variously as nursing caries, nursing bottle syndrome and so on. Although prolonged use of the baby bottle is believed to be associated with increased risk of caries, use of the bottle may not be the most important factor in caries development. The term early childhood caries (ECC) has been suggested because it more closely reflects the multifactorial etiologic process involved in the disease. A case of ECC treated in a general dental practice and managed under local anesthesia is reported.

The bioavailability of beta-carotene in stir- or deep-fried vegetables in men determined by measuring the serum response to a single ingestion

To evaluate the bioavailability of beta-carotene from plant foods, the serum beta-carotene response to a single ingestion of various beta-carotene sources was determined in 10 healthy men. Tested beta-carotene sources included stir-fried shredded carrot, stir-fried water convolvulus leaves, deep-fried sweet potato ball, purified beta-carotene in a capsule (beadlets) and beadlets with beta-carotene free oriental radish (beadlets + radish). The maximal change in serum beta-carotene concentration occurred at 24 or 32 h post ingestion. This response to beadlets was significantly higher than that to the other four tested beta-carotene sources (P < 0.05). The maximal serum response to beadlets + radish was also significantly higher than that to the three food beta-carotene sources (P < 0.05). The maximal serum response to sweet potato was significantly higher than that to water convolvulus leaves (P < 0. 05). The bioavailability relative to beta-carotene beadlets was calculated by dividing the maximal change in serum concentration to each test meal of each subject by his own serum maximal change in response to beadlets. Accordingly, the bioavailability was 65% for beadlets + radish, 33% for carrots, 26% for water convolvulus leaves and 37% for sweet potatoes. Concurrent ingestion of oriental radish reduced the bioavailability of beadlets to two-thirds of its original value, which partially accounted for the difference between the bioavailability of beadlets and natural foods. The relative bioavailability of beta-carotene from stir-fried and deep-fried vegetables was about one-third to one-fourth that of the purified beta-carotene beadlets. These bioavailabilities are higher than previously reported values.

Small cell carcinoma of the gallbladder: report of two cases

Two Taiwanese patients with gallbladder small cell carcinoma are reported. One is a 79 year-old male, the other, a 86 year-old female. They both presented with the symptom/signs of acute cholecystitis and underwent cholecystectomy. An intramural mass in the gallbladder neck region was found in the first patient, while the second patient had a transmural indurated tumor in the gallbladder body with extension to the neck region. Characteristic histological and immunohistochemical features of small cell carcinoma were present in both, and electron dense neurosecretory granules were identified in the second. To our knowledge, the second patient is the oldest ever reported. The first patient received chemotherapy directed toward the initial erroneous diagnosis of non-Hodgkin s lymphoma and developed liver metastasis in two months. The second patient did not receive chemotherapy due to her poor general condition and local recurrence occurred in six weeks. Both passed away three and five months after surgery, respectively.

Romano-Ward long QT syndrome: identification of a HERG mutation in a Taiwanese kindred

Romano-Ward syndrome is an autosomal dominant long-QT syndrome (LQTS) that predisposes affected individuals to sudden death from tachyarrhythmias. We investigated the molecular basis of LQTS in a Taiwanese kindred. Clinical and genetic analyses revealed that a mutation was linked to the human ether-a-go-go-related gene (HERG). The coding sequences and exon-intron borders of HERG were amplified by means of polymerase chain reaction and subjected to single-strand conformation polymorphism (SSCP) analysis. An exon with an aberrant SSCP pattern was cloned and sequenced to study the molecular lesion. A C-->T transition in codon 614, leading to substitution of a valine for an alanine residue in the pore region of the HERG protein, was identified. Analysis with Bsp12861 endonuclease digestion showed the mutation to be present in all affected family members. Given that an unaffected paternal uncle had inherited the same allele from the grandfather as the proband's father, a de novo mutation had apparently occurred in the father and was transmitted to his offspring. In addition to offering presymptomatic genetic diagnosis, identification of the disease-causing mutation may suggest new therapeutic approaches for treatment and prevention of this cardiovascular disease.

Detection and identification of Mycobacterium tuberculosis by nested PCR assays in cerebrospinal fluid samples from patients with suspected tuberculous meningitis

We used the nested polymerase chain reaction (PCR) assays developed previously to detect and identify Mycobacterium tuberculosis (M. tuberculosis) in the cerebrospinal fluid (CSF) samples from patients with suspected tuberculous meningitis and non-tuberculous patients. Our nested PCR assays target the multi-copy IS6110 insertion element and the single-copy mtp40 genomic DNA of M. tuberculosis. These assays, when used in combination, allowed us to detect a very low number of M. tuberculosis in the CSF samples, which otherwise would be undetectable by the culture method, and to distinguish M. tuberculosis from M. bovis. We applied these nested PCR assays to analyze eleven CSF samples. Among these, five of them were from patients with suspected tuberculous meningitis but all except one were culture negative. Our results of PCR assays show that three of these five are M. tuberculosis positive, one of which is M. bovis positive, and only one is M. tuberculosis negative. The other six CSF samples were from the clinically diagnosed non-tuberculous patients. Surprisingly, two of these so called non-tuberculous patients, a subarachnoid hemorrhage (SAH) and the syndrome of inappropriate antidiuretic hormone secretion (SIADH), were shown M. tuberculosis positive. This finding supports a long-standing argument that tuberculous meningitis is one of the causes of these neurological diseases. These nested PCR assays thus provide the neurologists with an important adjunct, in addition to the patient's clinical presentation and laboratory data, for the diagnosis of tuberculous meningitis.

Determination of the sensitivity and specificity of PCR assays using different target dnas for the detection of Mycobacterium tuberculosis

To establish a sensitive, specific and reproducible PCR assay for the detection of Mycobacterium tuberculosis, we evaluated three target DNAs: IS6110, 65 kDa heat shock protein gene; and mtp40 genomic fragment. We purified genomic DNA from 15 mycobacterial strains including four M. tuberculosis isolates, four M. bovis BCG isolates, and one of each for M. fortuitum, M. avium, M. intracellulare, M. szulgai, M. scrofulaceum, M. chelonei, and M. gordonae from the culture and used them as the template DNA. We studied 3 primer sets for IS6110, 2 primer sets for 65 kDa, and 3 primer sets for mtp40. Depending on the assay, these primer sets were used in the single-step PCR and/or nested PCR. The PCR assay targeting the 65 kDa protein gene could detect all of the tested mycobacterial strains, whereas targeting the IS6110 sequence resulted in detection of only M. tuberculosis and M. bovis BCG. Furthermore, targeting the mtp40 genomic fragment could be used to distinguish M. tuberculosis from M. bovis BCG. Using a nested PCR assay with primer sets specifically targeting the IS6110 or 65 kDa, we have been able to detect single copy M. tuberculosis genomic DNA. When the mtp40 genomic fragment was used as the target DNA, the sensitivity of detection was 10 copies of M. tuberculosis genomic DNA. This assay was demonstrated to have good sensitivity and specificity for detection and discrimination of mycobacterial species, and could be used in analyzing the clinical samples with low copy number infections such as the cerebrospinal fluid from the patient with tuberculous meningitis.

Patients' satisfaction with dental services provided by a university in Hong Kong

This study was a consumer evaluation of the dental care services provided by a university dental clinic in Hong Kong which provides dental care to all university students and staff and their dependents. The objectives of this study were to study the consumers' satisfaction with the dental services; to identify their reasons for not using the dental services; and to compare the opinions of the students with those of the university staff and their spouses. A total of 140 students and 180 staff and their spouses were randomly selected for this study. The response rates were 100 per cent for students and 77 per cent for staff and their spouses. Results showed that both groups of respondents were satisfied with the quality of dental services provided by the university dental clinic. However, they were not satisfied with the long waiting time for an appointment. Students who had not attended the university dental clinic commonly stated that they were busy and had no time for a dental visit. Conversely, many staff and their spouses did not seek care from the university dental clinic because they thought that the fees were high. Although the overall Dental Satisfaction Index (DSI) scores for the students (64.5) and staff and their spouses (65.1) were similar, there were differences in the aspects of the services with which the two group were satisfied or dissatisfied. Thus if the university dental clinic wants to implement changes so as to improve consumer satisfaction and utilisation, a careful analysis of the specific opinions of its various consumer groups is required.

An MTP inhibitor that normalizes atherogenic lipoprotein levels in WHHL rabbits

Patients with abetalipoproteinemia, a disease caused by defects in the microsomal triglyceride transfer protein (MTP), do not produce apolipoprotein B-containing lipoproteins. It was hypothesized that small molecule inhibitors of MTP would prevent the assembly and secretion of these atherogenic lipoproteins. To test this hypothesis, two compounds identified in a high-throughput screen for MTP inhibitors were used to direct the synthesis of a highly potent MTP inhibitor. This molecule (compound 9) inhibited the production of lipoprotein particles in rodent models and normalized plasma lipoprotein levels in Watanabe-heritable hyperlipidemic (WHHL) rabbits, which are a model for human homozygous familial hypercholesterolemia. These results suggest that compound 9, or derivatives thereof, has potential applications for the therapeutic lowering of atherogenic lipoprotein levels in humans.

Evidence that microsomal triglyceride transfer protein is limiting in the production of apolipoprotein B-containing lipoproteins in hepatic cells

The microsomal triglyceride transfer protein (MTP) is a heterodimeric lipid transfer protein that is required for the assembly and secretion of apolipoprotein B (apoB)-containing lipoproteins. A key unresolved question is whether the MTP-mediated step is rate limiting. To address this, a unique experimental strategy was used that allowed the in situ modulation and measurement of MTP triglyceride transfer activity. In order to accomplish this, an irreversible photoaffinity inhibitor, BMS-192951, was designed and synthesized. When incubated with purified MTP and irradiated with UV light at 360 nm, BMS-192951 inhibits triglyceride transfer by covalently binding to the protein. HepG2 cells were treated with either increasing concentrations of BMS-192951 (0-15 microM) with 5 min of ultraviolet irradiation, or 3.0 microM BMS-192951 with various lengths (0-15 min) of ultraviolet irradiation. Microsomal extracts were prepared exhaustively dialyzed to remove unbound inhibitor, and assayed for MTP-mediated triglyceride transfer activity. BMS-192951 was shown to reduce MTP activity in both a dose- and UV exposure time-dependent fashion. Measurement of apoB concentration in the media showed that apoB secretion was reduced in proportion to the in situ inhibition of MTP activity, while no change was observed in apoA-I secretion. Experiments performed in McArdle RH-7777 rat hepatoma cells and primary rat hepatocytes gave nearly identical results; the decrease in apoB secretion was proportional to the decrease in MTP activity. These results indicate that MTP-mediated lipid transfer is limiting in the assembly and secretion of apoB-containing lipoproteins in hepatic cells under the conditions tested.

Backbone and side chain dynamics of uncomplexed human adipocyte and muscle fatty acid-binding proteins

Adipocyte lipid-binding protein (A-LBP) and muscle fatty acid-binding protein (M-FABP) are members of a family of small ( approximately 15 kDa) cytosolic proteins that are involved in the metabolism of fatty acids and other lipid-soluble molecules. Although highly homologous (65%) and structurally very similar, A-LBP and M-FABP display distinct ligand binding characteristics. Since ligand binding may be influenced by intrinsic protein dynamical properties, we have characterized the backbone and side chain dynamics of uncomplexed (apo) human A-LBP and M-FABP. Backbone dynamics were characterized by measurements of 15N T1 and T2 values and ¿1H¿-15N NOEs. These data were analyzed using model-free spectral density functions and reduced spectral density mapping. The dynamics of methyl-containing side chains were charaterized by measurements of 2H T1 and T1rho relaxation times of 13C1H22H groups. The 2H relaxation data were analyzed using the model-free approach. For A-LBP, 15N relaxation data were obtained for 111 residues and 2H relaxation data were obtained for 42 methyl groups. For M-FABP, 15N relaxation data were obtained for 111 residues and 2H relaxation data were obtained for 53 methyl groups. The intrinsic flexibilities of these two proteins are compared, with particular emphasis placed on binding pocket residues. There are a number of distinct dynamical differences among corresponding residues between the two proteins. In particular, many residues display greater backbone picosecond to nanosecond and/or microsecond to millisecond time scale mobility in A-LBP relative to M-FABP, including F57, K58, and most residues in alpha-helix 2 (residues 28-35). Variations in the dynamics of this region may play a role in ligand selectivity. The side chains lining the fatty acid binding pocket display a wide range of motional restriction in both proteins. Side chains showing distinct dynamical differences between the two proteins include those of residues 20, 29, and 51. This information provides a necessary benchmark for determining dynamical changes induced by ligand binding and may ultimately lead to an enhanced understanding of ligand affinity and selectivity among fatty acid-binding proteins.

Entrapment of index flexor digitorum profundus and median nerve: an unusual complication of distal radial fracture--a case report

A case of index flexor digitorum profundus and median nerve entrapment by bony fracture after reduction as a complication of distal radial fracture in an 11-year-old male is described. After release of tendon and nerve the patient had a good functional result.

An inhibitor of the microsomal triglyceride transfer protein inhibits apoB secretion from HepG2 cells

The microsomal triglyceride (TG) transfer protein (MTP) is a heterodimeric lipid transfer protein that catalyzes the transport of triglyceride, cholesteryl ester, and phosphatidylcholine between membranes. Previous studies showing that the proximal cause of abetalipoproteinemia is an absence of MTP indicate that MTP function is required for the assembly of the apolipoprotein B (apoB) containing plasma lipoproteins, i.e., very low density lipoproteins and chylomicrons. However, the precise role of MTP in lipoprotein assembly is not known. In this study, the role of MTP in lipoprotein assembly is investigated using an inhibitor of MTP-mediated lipid transport, 2-[1-(3, 3-diphenylpropyl)-4-piperidinyl]-2,3-dihydro-1H-isoindol-1-o ne (BMS-200150). The similarity of the IC50 for inhibition of bovine MTP-mediated TG transfer (0.6 microM) to the Kd for binding of BMS-200150 to bovine MTP (1.3 microM) strongly supports that the inhibition of TG transfer is the result of a direct effect of the compound on MTP. BMS-200150 also inhibits the transfer of phosphatidylcholine, however to a lesser extent (30% at a concentration that almost completely inhibits TG and cholesteryl ester transfer). When BMS-200150 is added to cultured HepG2 cells, a human liver-derived cell line that secretes apoB containing lipoproteins, it inhibits apoB secretion in a concentration dependent manner. These results support the hypothesis that transport of lipid, and in particular, the transport of neutral lipid by MTP, plays a critical role in the assembly of apoB containing lipoproteins.

A pilot study of the marginal adaptation and surface morphology of glass-cermet cements

This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months.

Crystallization of microsomal triglyceride transfer protein from bovine liver

The microsomal triglyceride transfer protein (MTP) is a heterodimeric lipid transfer protein required for the assembly of plasma very low density lipoproteins in the liver and chylomicrons in the intestine. Bovine MTP was purified by a modification of a previously published procedure and crystals of MTP were grown reproducibly with polyethylene glycol as a precipitant at pH 7.0. MTP crystals, which diffract to Bragg spacings of better than 3.2 A, have the symmetry of space group P2(1)2(1)2(1) with refined lattice constants of a = 88.7, b = 100.9 and c = 201.1 A, with one heterodimer per asymmetric unit.

Microsomal triglyceride transfer protein. Specificity of lipid binding and transport

Microsomal triglyceride transfer protein (MTP) is a lipid transfer protein that is required for the assembly and secretion of very low density lipoproteins by the liver and chylomicrons by the intestine. To further elucidate the nature of the lipid molecule binding and transport site on MTP, we have studied the relative rates at which MTP transports different lipid species. Assay conditions were chosen in which there were minimal changes in the physical properties of the substrate membranes so that transfer rates would reflect MTP-lipid interactions at a membrane surface. Lipid transport rates decreased in order of triglyceride > cholesteryl ester > diglyceride > cholesterol > phosphatidylcholine. Changes in the hydrophobic nature of a lipid molecule by the addition of a fatty acid, modulated the ability of MTP to transport it. Addition of one acyl chain from diglyceride to triglyceride, lysophosphatidylcholine to phosphatidylcholine, or cholesterol to cholesteryl ester increased the rate of MTP-mediated transport 10-fold. In contrast, the lipid transport rate was insensitive to the changes in the structure or charge of the polar head group on phospholipid substrates. Zwitterionic, net negative, or net positive charged phospholipid molecules were all transported at a comparable rate. The ability of MTP to transport lipids is strongly correlated to the binding of these lipids to MTP. Thus, MTP has a specific preference for binding and transporting nonpolar lipid compared with phospholipids, and within a class of lipid molecules, a decrease in polarity increases its tendency to be transported.

DNA ploidy and biologic aggressiveness of gastric adenocarcinoma in Chinese

The mortality rate of gastric cancer in the Chinese population has reached a plateau. The main prognostic factor for gastric adenocarcinoma is recognized as tumor stage. Recently, abnormalities in DNA content have been considered as a new prognostic factor. Whether abnormal DNA content can be used as a prognostic tool for Chinese patients with gastric cancer is unknown. To investigate this relation DNA ploidy and prognosis of gastric cancer patients were studied using paraffin-embedded specimens. A group of 104 newly diagnosed and surgically resected gastric cancer specimens obtained from January 1984 to December 1986 were examined for DNA content by flow cytometry. The quality of flow cytometry was acceptable with a mean coefficient of variance of 5.45. The results showed that 38 cases (36.5%) had DNA aneuploidy; 42 cases had metastatic lymph nodes with enough tumor cells, and 31.0% of these cases had DNA aneuploidy. DNA aneuploidy of primary tumors was correlated to lymph node metastasis and patient's age, whereas DNA aneuploidy of metastatic lymph nodes was significantly correlated to the serosal invasion of the gastric wall at the primary site. The important parameters for prognosis were curability of surgical resection, serosal invasion, tumor size, and distant metastasis. DNA aneuploidy of both primary tumors or metastatic lymph nodes appeared to be unrelated to the prognosis of gastric adenocarcinoma in Chinese patients. We therefore propose that DNA aneuploidy of gastric cancer is associated with tumor growth but not biologic aggressiveness.

Alternative adrenal chromaffin cell fates induced by basic fibroblast growth factor or cyclic AMP in vitro depend on a collaboration with the growth substrate

Basic fibroblast growth factor stimulates cultured adrenal chromaffin cells to divide and to transform into sympathetic neurons, but the efficacies reported for these actions of basic fibroblast growth factor have varied widely. We have examined the effect of various growth substrates on basic fibroblast growth factor responses and here we show that the ability of basic fibroblast growth factor to transform neonatal rat chromaffin cells into sympathetic neurons depends on laminin as the culture substrate. On collagen, less than 5% of the cells were transformed into neurons by basic fibroblast growth factor, even when the culture was supplemented with heparin or heparan sulphate, but 65% of cells entered the S phase in the presence of basic fibroblast growth factor compared to 15% in its absence, showing that the basic fibroblast growth factor receptor is still active. On laminin, by contrast, over 60% of the cells transformed into neurons in response to the same concentrations of basic fibroblast growth factor, suggesting that an overlapping pool of cells change their phenotype depending on growth substrate. The cyclic AMP analogue 8-(4-chlorophenylthio)cyclic AMP apparently mimicked the actions of basic fibroblast growth factor, promoting neuronal differentiation on laminin, but mitogenic stimulation on collagen. These data support the notion that collagen and laminin promote different instructions in chromaffin cells that can collaborate with the signals induced by basic fibroblast growth factor and 8-(4-chlorophenylthio)cyclic AMP to determine chromaffin or neuronal cell fates.

Effects of histamine on intracellular Na+ activity and twitch tension in guinea pig papillary muscles

Effects of histamine on the twitch tension, intracellular Na+ activity (aiNa), and action potential were simultaneously and continuously measured in the isolated cardiac papillary muscle of guinea pigs. In the driven fiber at 60 beats/ min, histamine induced a concentration-dependent positive inotropic effect, and apparently increased the amplitude of the action potential and shortened the duration at 3 microM, and significantly decreased aiNa by 6.7% from the control value of 4.5 +/- 0.1 mM (n = 6, p < 0.05) at 0.3 microM. Cimetidine at 10 microM did not produce any significant effect but partially antagonized the action of histamine. The respective concentrations of 1 and 3 microM histamine significantly decreased aiNa by 5.4 and 14.3% from the control 5.6 +/- 0.1 mM (n = 6, p < 0.05) in the presence of 10 microM cimetidine. Chlorpheniramine at 10 microM significantly reduced the twitch tension and aiNa, and prolonged the action potential duration. Histamine at 1 microM increased the twitch tension and decreased aiNa from 4.5 +/- 0.1 to 4.1 +/- 0.1 mM (n = 5, p < 0.05) in the presence of 10 microM chlorpheniramine. The combined application of 10 microM cimetidine and 10 microM chlorpheniramine reduced the twitch tension and abolished most effects of histamine. In high potassium solution (16.2 mM), 1 microM histamine significantly decreased aiNa by 12.9% from the control of 3.1 +/- 0.2 mM (n = 5, p < 0.05). The treatment of 0.5 or 1 microM ouabain increased the tension development and aiNa, and abolished the decrease in aiNa produced by the effect of histamine. The results suggest that histamine can directly stimulate Na-K pump in sarcolemma through means of the activation of both H1- and H2-receptors.