Ethnic distribution of slow acetylator mutations in the polymorphic N-acetyltransferase (NAT2) gene

The acetylation polymorphism may affect rates of activation or detoxification of common carcinogens, thereby influencing cancer risk. Our aim was to define the ethnic distribution of the major slow acetylator mutations in the polymorphic N-acetyltransferase gene, in order to provide background data for epidemiological studies. Our results contain new analyses on 803 individuals, including 365 new specimens and 438 specimens that had been partly characterized in an earlier study. Tests were done to establish the specificity and reproducibility (98%) of our PCR assays. The recognized slow acetylator mutations, 191A, 481T, 590A, and 857A (which correspond to alleles M4 and M4b; M1 and r3; M2/r2; and M3 and S3, respectively), accounted for nearly all slow acetylator alleles among blacks, whites, Asian Indians, Hispanics, Koreans, Japanese, Hong Kong Chinese, Taiwanese, Filipinos and Samoans. The ethnic distribution supports an interpretation that the acetylation polymorphism existed before Paleolithic splitting of human populations from Africa. We identified two additional NAT2 mutations, suggesting that other rare alleles are likely to be found.

Ethnic distribution of the glutathione transferase Mu 1-1 (GSTM1) null genotype in 1473 individuals and application to bladder cancer susceptibility

Polycyclic aromatic hydrocarbons, found in cigarette smoke, food and industrial materials, are potential human carcinogens. Deficiency of detoxifying enzymes, such as glutathione transferases, may affect the metabolic fates of these chemicals and raise cancer risks in exposed individuals. The GSTM1 null genotype is a common form of glutathione transferase deficiency. Because knowledge of its ethnic distribution would be useful in epidemiologic studies, we measured the frequencies of the GSTM1 null genotype among healthy blacks, whites, Asian Indians, Chinese, Japanese, Koreans, Filipinos, Samoans and Hispanics. Rapid genotyping was done by use of a PCR assay, with dried blood spots on blotter paper as DNA templates. The frequency of the null genotype ranged from 0.31 among blacks to 0.88 among Samoans. The PCR assay was also applied to a pilot study of 114 bladder cancer cases from Kaiser Permanente Medical Center, Harbor City, California. DNA for these cases was obtained from paraffin-embedded surgical specimens. The overall odds ratio for bladder cancer with the GSTM1 null genotype was 1.4 (95% confidence interval 0.94-2.1), indicating no statistical difference in null genotype frequencies among bladder cancer patients compared to a healthy population. Large epidemiologic studies, which can be accomplished with dried blood spots or paraffin-embedded tissue specimens, may be useful for further assessment.

Thoracic epidural anesthesia for major abdominal surgery: a retrospective study

In 1986-1988, the authors had experiences with thoracic epidural anesthesia for a variety of major abdominal operations in 303 patients. It is proved to be reliable and effective. The puncture levels were between T8 to T12. 2% lidocaine, in plain form or with 1:200,000 epinephrine, was used as anesthetic agent. Perioperative complications were carefully managed with satisfactory results. Post-operative conditions were evaluated and seemed to be superior to those of general anesthesia in many aspects. No patient had neurologic deficit as a result of the epidural anesthesia. We concluded that thoracic epidural anesthesia is an excellent alternative technique in major abdominal surgeries.

Noninvasive hemodynamic classification of carotid-cavernous sinus fistulas by duplex carotid sonography

The hemodynamic classification of the CCF has important implications for prognosis and therapy, but satisfactory criteria for such a differentiation are still lacking. We studied the application of extracranial duplex sonography in 14 cases of CCF with emphasis on the hemodynamic parameters of the RI and flow volume and made a correlation with the angiographic findings. We conclude with proposed duplex sonographic criteria for hemodynamic classification: (1) small RI with increased flow volume in the ICA: direct ICA-cavernous sinus fistulas (type A); (2) normal RI and flow volume in the ICA and ECA: dural branch of ICA-cavernous sinus fistulas (type B); (3) small RI with or without increased flow volume in the ECA: dural branch of ECA-cavernous sinus fistulas (type C) or dural branches of ICA- and ECA-cavernous sinus fistulas (type D). Application for assessment of the therapeutic effectiveness was also demonstrated.

Non-A, non-B fulminant hepatitis is also non-E and non-C

OBJECTIVES

to define the roles of the hepatitis C and E viruses (HCV and HEV) in non-A, non-B (NANB) fulminant hepatitis.

METHODS

we utilized the polymerase chain reaction to amplify HCV and HEV RNA sequences and assays to detect antibodies to HCV and HEV in the acute phase sera of eight presumed viral NANB and seven nonviral NANB fulminant hepatic failure (FHF) patients.

RESULTS

none of the 15 patients had detectable HCV or HEV RNA or elevated HCV and IgM-HEV antibody titers in their acute phase sera. Three patients, all with features of autoimmune hepatitis, had raised IgG-HEV antibody titers. Due to the possibility of serologically undetectable hepatitis B virus (HBV) infection in fulminant hepatitis patients, we performed polymerase chain reaction amplification of HBV genomic DNA in acute phase sera of the presumed viral NANB FHF patients and subsequently found no evidence of HBV DNA.

CONCLUSIONS

we did not find evidence implicating HCV or HEV in presumed viral NANB FHF or as agents contributing to or causing the liver failure in nonviral NANB FHF patients with autoimmune hepatitis, drug-induced hepatotoxicity, or halothane hepatotoxicity.

Establishment of a quality assurance program for human immunodeficiency virus type 1 DNA polymerase chain reaction assays by the AIDS Clinical Trials Group. ACTG PCR Working Group, and the ACTG PCR Virology Laboratories

An independent quality assurance program has been established by the Virology Committee of the AIDS Clinical Trials Group in the Division of AIDS, National Institute of Allergy and Infectious Diseases, for monitoring polymerase chain reaction (PCR) assays for human immunodeficiency virus type 1 (HIV-1) DNA that are performed by 11 laboratories participating in multicenter clinical trials in the United States. To perform HIV-1 DNA PCR for patients in AIDS Clinical Trials Group protocols, each laboratory was initially certified by correctly testing a coded certification panel consisting of eight well-defined clinical whole-blood specimens and 30 cell pellets containing 0, 2, 5, 10, 20, or 50 8E5/LAV cells per 125,000 uninfected peripheral blood mononuclear cells. PCR was performed by one of two standardized commercial assays for amplification and nonisotopic detection of HIV-1 proviral DNA. For continuing certification, each laboratory must correctly test eight coded whole-blood samples per quarter and run three or four coded cell pellets and HIV-1 DNA copy standards with every PCR assay in real time. The PCR results for the coded pellets on each run are entered into an encrypted computer file, which immediately assesses the validity of the run. To date, 10 of 11 laboratories have correctly tested all HIV-1-positive and -negative samples in the initial certification panel on their first or second attempt. Subsequently, 9 of these 11 laboratories have continued to maintain their certified status. The use of commercial HIV-1 DNA PCR assays and an external quality assurance program have ensured that results from different laboratories are comparable and that problems with sensitivity and specificity are quickly identified.

Refractoriness of neuromuscular transmission: determination by computer subtraction of neurally evoked compound electromyograms

Shortly after elicitation of a muscle response by supramaximal stimulation of its motor nerve, there exists a period of refractoriness of neuromuscular transmission when a second stimulation elicits only a submaximal response or no response at all. Many anaesthetics and neuromuscular blocking and facilitatory drugs change the refractoriness of neuromuscular transmission. Measurement of this refractoriness may improve our understanding of the neuromuscular actions of these drugs and be useful in differential diagnosis. However, the neuromuscular refractory periods (RP) are difficult to measure, and the unavailability of normal values renders accurate determination of drug effects impossible. Based on an existing technique of digitization and time expansion of the neurally evoked compound electromyogram (ncEMG), we developed a computer programme of waveform subtraction, and determined in nine normal awake volunteers the various interstimulus intervals when neuromuscular transmission was refractory (RP0), 3/4 refractory (RP.25), half refractory (RP.5), 1/4 refractory (RP.75) or non-refractory (RP1). We confirmed our hypotheses that computer-based waveform subtraction of the digitized ncEMG is a feasible and necessary technique for the accurate determination of the RPs of neuromuscular transmission, and report that the normal values in humans are: RP0 = 1.0 +/- 0.1, RP.25 = 1.3 +/- 0.3, RP.5 = 1.9 +/- 0.3, RP.75 = 2.9 +/- 0.5, and RP1 = 6.6 +/- 1.9 ms (mean +/- SD), respectively, in the ulnar nerve-first dorsal interosseous muscle model.

Hepatitis C virus infection in kidney transplant recipients

To determine the prevalence and significance of hepatitis C virus infection in kidney transplant recipients, paired serum samples collected from 100 renal allograft recipients on admission for kidney transplantation and 1 yr after transplantation were tested for antibody to hepatitis C virus with second-generation enzyme immunoassay and recombinant immunoblot assay and for hepatitis C virus RNA with reverse transcription-polymerase chain reaction. Before kidney transplantation, hepatitis C virus antibody was detected with second-generation enzyme immunoassay in 18 patients (12 second-generation recombinant immunoblot assay-positive, 6 second-generation recombinant immunoblot assay-indeterminate). Nine of 12 second-generation recombinant immunoblot assay-positive and 2 of 6 second-generation recombinant immunoblot assay-indeterminate samples were hepatitis C virus RNA positive. In addition, 7 of 82 patients who had no detectable antibody on second-generation enzyme immunoassay or second-generation recombinant immunoblot assay were hepatitis C virus RNA positive. After kidney transplantation, hepatitis C virus antibody was detected in 19 patients (12 second-generation recombinant immunoblot assay-positive, 7 second-generation recombinant immunoblot assay-indeterminate, 14 seropositive for hepatitis C virus antibody). Eleven of 12 patients with second-generation recombinant immunoblot assay-positive results and 4 of 7 with second-generation recombinant immunoblot assay-indeterminate results were positive for hepatitis C virus RNA. Hepatitis C virus RNA was present in 28 patients 1 yr after kidney transplantation. Six patients appeared to have acquired active hepatitis C virus infection 1 yr after kidney transplantation (seroconverted to hepatitis C virus RNA positivity).(ABSTRACT TRUNCATED AT 250 WORDS)

Soft x-ray magnetic circular dichroism: a probe for studying paramagnetic bioinorganic systems

Soft x-ray magnetic circular dichroism was used to study a paramagnetic bioinogranic system. We measured the Fe L edges of Pyrococcus furiosus rubredoxin, using circularly polarized synchrotron radiation, a split-coil super-conducting magnet, low sample temperatures, and fluorescence detection. The observed dichroism effect is strong (30%) and in general agreement with the calculation. The method is element- and oxidation state-specific, and the data can be interpreted by established theoretical procedures. Soft x-ray magnetic circular dichroism demonstrates enormous potential as a probe for studying paramagnetic systems in biology, chemistry, and material science.

The hepatitis C virus genome: a guide to its conserved sequences and candidate epitopes

A comprehensive analysis of reported hepatitis C virus genomic sequences comprising 151 partial or complete nucleotide sequences and 159 partial or complete amino acid sequences revealed an irregular composition of conserved and variable regions. There were but eight conserved nucleotide sequences, none outside the 5' noncoding and structural regions. A search among conserved amino acid sequences revealed 14 candidate B-cell epitopes, which were chosen mainly on the basis of their hydrophilicity profiles. Twenty five candidate T-cell epitopes were selected according to the criteria of absolute conservation of amino acid sequence, together with characteristic sequence motifs, amphipathic helical structure, or both. Conserved peptide sequences, with the characteristics of both B- and T-cell epitopes, were identified in the nonstructural 5 (NS5) region of the genome.

Five-year follow-up of a prospective randomized trial of hepatitis B recombinant DNA yeast vaccine vs. plasma-derived vaccine in children: immunogenicity and anamnestic responses

In a prospective randomized trial, 318 children aged between 3 mo and 11 yr who were negative for all hepatitis B markers were randomized to receive two 5-micrograms doses of hepatitis B recombinant DNA yeast vaccine at 0 and 1 mo (group 1), three 5-micrograms doses of hepatitis B recombinant DNA yeast vaccine at 0, 1 and 6 mo (group 2) or three 10-micrograms doses of plasma-derived hepatitis B vaccine (group 3). The HBs antibody response rate at 8 mo was between 93% and 99%; it was still 75% to 87% at 5 yr in all three groups. Geometric mean titers at 1 yr were 83, 1,085 and 858 mIU/ml in groups 1, 2 and 3, respectively. These values had decreased after 5 yr to 47, 131 and 250 mIU/ml. Subjects in group 1 showed a significantly less proportional drop in geometric mean titer at the fifth year than did subjects in group 2 (p = 0.05) or group 3 (p = 0.015). None of the children developed HBc antibody, even after 5 yr of follow-up. We noted 42 episodes of significantly increased HBs antibody titers, probably due to anamnestic response, even when the titers had dropped to low levels. The mean age at which anamnestic response occurred was 8.7 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

DOOR syndrome (deafness, onycho-osteodystrophy, and mental retardation): a new patient and delineation of neurologic variability among recessive cases

We report the seventeenth case of the recessive form of the DOOR syndrome. The parents were Guatemalan and not known to be consanguineous. The patient had developmental delay, severe sensorineural deafness, and abnormal nails and phalanges in the hands and feet. Urinary 2-oxoglutarate excretion was normal. The patient was among a subset of DOOR syndrome patients without seizures in infancy. This observation may be useful in discussing the prognosis for newly identified cases.

Aspergillosis complicating the grafted skin and free muscle flap in a diabetic

A case of infected diabetic foot ulcer was reconstructed by a free muscle flap overlaid with a skin graft. Primary cutaneous aspergillosis involving the grafted skin and the transplanted muscle was described. The patient presented with an indurated grey-yellow plaque or black eschar in the wound without purulent discharge. Biopsies and cultures demonstrated A. flavus as the etiologic agent without evidence of systemic dissemination. Early diagnosis necessitates a high index of suspicion in immunocompromised patients with unusual cutaneous manifestation. Treatment consisted of aggressive debridement, systemic and local antifungal therapy, and delayed grafting. We concluded that primary cutaneous aspergillosis may occur at the reconstructed wound in an immunocompromised diabetic, and that it is a rare complication requiring prompt diagnosis and treatment.

Is sclerosant injection mandatory after an epinephrine injection for arrest of peptic ulcer haemorrhage? A prospective, randomised, comparative study

A prospective, randomised, comparative study was performed to assess the need for a pure alcohol injection after an epinephrine injection in the arrest of active peptic ulcer bleeding. Sixty four patients with active ulcer bleeding were enrolled in the study. The two groups (epinephrine and epinephrine plus pure alcohol) were matched for sex, age, site of bleed, endoscopic findings, shock, haemoglobin, and concomitant illness at randomisation. The volume of injected epinephrine in the epinephrine and the epinephrine plus pure alcohol groups mean (SD) was 6.0 (3.0) ml and 5.5 (3.0) ml respectively (p > 0.05). The volume of injected pure alcohol in the epinephrine plus pure alcohol group was 1.9 (1.1) ml. Bleeding was initially controlled in 31 (97%) of the epinephrine group and all of the epinephrine plus pure alcohol group. Rebleeding occurred in 11 (36%) of the epinephrine group and in five (16%) of the epinephrine plus pure alcohol group (p > 0.05). Rebleeding was successfully controlled in some patients with treatment by a second injection. Other patients had heat probe thermocoagulation or surgery. Ultimate haemostatic rates were 69% (22/32) and 88% (28/32) for the epinephrine and the epinephrine plus pure alcohol groups respectively (p > 0.05). The epinephrine plus pure alcohol group achieved a better haemostatic effect for spurting haemorrhage (9/10 v 5/11, p < 0.05). The need for emergency operations and blood transfusions were comparable in both groups. The stay in hospital were less in the epinephrine plus pure alcohol group (mean 4.3 v 7.1, p < 0.05). It is concluded that pure alcohol injection after an epinephrine injection can improve the haemostatic rate in patients with spurting haemorrhage and shorten the hospital stay for patients with active bleeding.

[Congenital nasopharyngeal teratoma: report of a case and review of the literature]

Teratomas are the most common congenital tumors, but teratomas of the nasopharynx are rare and seen almost exclusively in infants, usually in neonates. An unusual case of a neonate with respiratory distress is presented and a nasopharyngeal mass protruding into the oral cavity. After successful removal of the mass, pathological examination revealed a mature teratoma. The management and differential diagnosis are discussed, accompanied by a review of the literature.

[Value of fine needle aspiration cytology in the diagnosis and management of fibroadenoma of the breast]

Cytological and histopathological biopsies were obtained from 121 breast lumps clinically diagnosed as fibroadenomas. Of these 98.3 percent of the lesions were benign. The cytological diagnosis was benign in 95.1 percent of 101 (83.4% of total) cases confirmed as fibroadenomas, histopathologically, but inadequate for diagnosis in 4.9 percent. The remaining 20 lesions included one breast cancer and one primary malignant lymphoma. In this group aspiration cytology was inadequate for diagnosis in 20 percent of the cases (P < 0.05). The cytological reports cast suspicion in the two malignant cases. No lesion with benign cytology was subsequently shown to be malignant. Ninety-five (78.5%) cases of the lesions, representing 72 women under 35 years of age, which has been clinically diagnosed as fibroadenomas, showed fibroadenoma, histopathologically, in 89.5% of these cases. The other 26 (21.5%) lesions in 21 patients, who were over 35 years in age, had 61.5 percent fibroadenomas, cytological results cast suspicion of fibroadenoma in 87.1 percent of these cases. The other 16 histopathologically diagnosed fibroadenomas in patients over 35 years of age showed 62.5% were cytologically suspected of being fibroadenomas (P < 0.025). As a result of this study it is reasonable to suggest that a typical clinical fibroadenoma can be treated conservatively in women under 35 years, but only if an adequate cytological smear obtained by fine needle aspiration does not show malignant of suspicious cells.

Adenomyoma of the papilla of Vater: a case report

Adenomyoma of the papilla of Vater is exceedingly rare. Histologically, the adenomyoma is characterized by locules of ducts with interlacing bundles of smooth muscle. A 63-year-old male patient is presented who had developed abdominal pain, progressively darker urine and light color stool, jaundice and dyspepsia over the past two-month period. Impression from radiologic study was neoplasm of the papilla of Vater, pathologic findings proved adenomyoma. This case, and review of the literature, suggest that local excision is the treatment-of-choice.

Randomized controlled trial of recombinant alpha-2a-interferon for chronic hepatitis C. Comparison of alanine aminotransferase normalization versus loss of HCV RNA and anti-HCV IgM

We enrolled 32 patients with chronic hepatitis C into a randomized, controlled trial to evaluate the efficacy of recombinant alpha-2a-interferon treatment. Sixteen patients were randomized to receive 1.5 million units of recombinant alpha-2a-interferon subcutaneously, thrice weekly, for six months while the remaining 16 patients were randomized to a control group that received no treatment. The mean serum alanine aminotransferase (ALT) level during the six-month study period, expressed as a percentage of the prestudy baseline value, was 82% for the control group compared to 56% for the treatment group (P = 0.014). One fourth of the treatment group normalized their serum ALT level compared to only 6% of the controls (P = 0.05). During posttherapy follow-up, 86% of responders clinically relapsed. Loss of anti-HCV IgM and HCV RNA occurred exclusively in interferon-treated responders. Anti-interferon antibodies developed in 32% of all treated patients. Forty percent of nonresponders developed anti-interferon antibodies compared to only 14% of responders (P = NS). We conclude that recombinant alpha-2a-interferon is clinically effective in patients with chronic hepatitis C. However, most responders in this trial of low-dose interferon relapsed upon cessation of treatment.

Slow acetylator mutations in the human polymorphic N-acetyltransferase gene in 786 Asians, blacks, Hispanics, and whites: application to metabolic epidemiology

Our aim was to determine the population frequencies of the major slow acetylator alleles of the polymorphic N-acetyltransferase (NAT2) gene, whose locus maps to chromosome 8. We used allele-specific PCR amplification on 786 dried blood spots obtained from Hong Kong Chinese, U.S. Koreans, U.S. blacks, U.S. Hispanics, Germans, and U.S. whites. Our results show that four slow acetylator alleles can be detected as mutations at positions 481, 590, and 857 in the NAT2 gene. Recognized base substitutions at positions 341 and 803 need not be determined, because they were almost always associated with the 481T mutation. The known mutation at position 282 was strongly associated with the 590A mutation. The 481T, 590A, and 857A mutations accounted for virtually all of the slow acetylator alleles in Asian and white populations. The 857A mutation proved to be an Asiatic allele. The results will be useful in large-scale epidemiologic studies of cancer and other conditions potentially associated with the acetylator polymorphism.

Exstrophy of the cloaca in a 47,XXX child: review of genitourinary malformations in triple-X patients

Cloacal exstrophy, unilateral renal agenesis, and Müllerian anomalies occurred in a liveborn infant with a 47,XXX chromosome constitution. The patient extends the range of genitourinary anomalies reported in triple-X patients. Screening asymptomatic patients for urinary tract abnormalities may be useful in searching for silent malformations potentially associated with this karyotype.

The variability of the hepatitis B virus genome: statistical analysis and biological implications

A statistical analysis of the nucleotide sequence variability in 14 published hepatitis B virus (HBV) genomes was carried out using parametric and nonparametric methods. A parametric statistical model revealed that the different regions of the genome differed significantly in their variability. The conclusion was supported by a nonparametric kernel-density model of the HBV genome. Genes S, C, and P, region X, the precore region, and the pre-S2/pre-S1 regions were ranked in order of increasing variability. In many instances, conserved regions of the genome identified with sequences of known function in HBV biology. However, other characterized regions (such as pre-S) showed much variability despite the involvement of their encoded peptides in specific functions. Point mutations that may result in the formation of stop codons and amino acid changes may affect the clinical picture of HBV infection and may be reflected in atypical serological patterns.

Recombinant interferon-alpha in inoperable hepatocellular carcinoma: a randomized controlled trial

To evaluate the clinical efficacy of interferon-alpha in hepatocellular carcinoma, 71 adult Chinese patients with histologically proven inoperable hepatocellular carcinoma were randomized to receive recombinant interferon-alpha 2a (50 x 10(6) IU/m2) intramuscularly three times a week (n = 35) or no antitumor therapy (n = 36). The survival of interferon-alpha-treated patients was significantly better than that of patients who received no antitumor therapy (p = 0.0471); median lengths of survival were 14.5 and 7.5 wk, respectively. Objective tumor regression greater than 50% was observed in 31.4% (11 of 35) of patients receiving interferon-alpha. Interferon-alpha induced tumor regression greater than 50% in 11 (31.4%) patients. Compared with the group receiving no antitumor therapy, the interferon-alpha therapy group had more tumor regression (p < 0.0001) and less tumor progression (p = 0.001). This high-dose interferon-alpha therapy was relatively well tolerated; only 34.3% of patients required reduction of dosage by one third or one half because of persistent fatigue. Two patients with diabetes mellitus (one also had tabes dorsalis) exhibited mental deterioration that might have been partially attributable to interferon-alpha therapy. We conclude that interferon-alpha is useful in a proportion of Chinese patients with inoperable hepatocellular carcinoma, both in prolonging survival and in inducing tumor regression.

Endoscopic injection for the arrest of peptic ulcer hemorrhage: final results of a prospective, randomized comparative trial

A prospective, randomized comparative study was performed to compare the hemostatic effect of endoscopic injection with normal saline, 3% NaCl solution, 50% glucose/water solution, and pure alcohol during a period of 2 years. Only patients with peptic ulcers and active bleeding or nonbleeding visible vessels were considered. Each group comprised 50 patients. The four groups were matched at random for age, sex, location of bleeders, stigmata of recent hemorrhage, shock, hemoglobin, and concomitant illness. No statistically significant difference was observed among patients injected with normal saline, 3% NaCl solution, 50% glucose/water solution, or pure alcohol in achieving initial hemostasis (82%, 90%, 86%, and 92%, respectively); rebleeding rates (7.3%, 24.4%, 14%, and 10.9%, respectively); ultimate hemostasis (78%, 68%, 78%, and 84%, respectively); number of emergency operations (5, 7, 4, and 3, respectively); and average number of days in the hospital (6.7, 6.1, 6.1, and 5.8, respectively). A tendency toward a lower blood transfusion requirement was observed in the pure alcohol group, but this tendency failed to achieve statistical significance. One patient had a perforated ulcer develop 5 days after injection of 3 ml 50% glucose/water. Otherwise, no major complication was observed. We suggest that endoscopic injection with any of the above solutions can be used as the first-line modality for the arrest of peptic ulcer hemorrhage.

Methanol for preparing hair bulbs for PCR

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Polymerase chain reaction assay for hepatitis C virus RNA using a single tube for reverse transcription and serial rounds of amplification with nested primer pairs

A procedure is described for the detection of hepatitis C virus (HCV) RNA in blood by means of the polymerase chain reaction (PCR) in which the reverse transcription step and two rounds of amplification are carried out in a single tube. This results in fewer manipulations, reduced risk of contamination, and economy of time. The procedures are generally applicable to other assays based on the PCR. We describe the preparation (from 100 microL serum) of test samples that remain stable for at least 6 days under specified conditions and an assay that employs nested primer pairs homologous to conserved sequences in the 5' noncoding region. The method was tested on 107 sera from the United States and Japan. Correlation with first-generation anti-HCV was 77%. Two sets of nested primer pairs homologous to sequences in the 5' noncoding region and one set based on structural region sequences showed differences in their reactivities with serum HCV RNA. The recommended single tube procedure specified a primer for reverse transcription that was conserved in all reported HCV genomes but absent from pestivirus genomic sequences. The effects of preanalytical factors on the detection of HCV RNA were studied. Qualitatively, there was no change in the HCV RNA-positivity of sera that were exposed to room temperature for 24 hours. Quantitative studies showed a decrease in titer in some specimens. Three cycles of freeze-thawing had no detectable effects on the titers of HCV RNA.

[Ileal inflammatory fibroid polyp: case report]

The inflammatory fibroid polyp is a rare, polypoid lesion in the gastrointestinal tract. It occurs in the stomach, small intestine, and large intestine in descending order of frequency. This case report shows an ileal inflammatory fibroid polyp that causes ileoileal intussusception. So far, the histogenesis and pathogenesis of these kinds of polyps are still uncertain. Under the microscopic examination, the lesion appears to be made up of spindle-shaped or stellate cells that are morphologically identical to proliferating fibroblasts. Immunostaining results are strongly positive for vimentin and focally positive for S100 protein. However, epithelial membrane antigen, factor VIII R Ag, smooth muscle actin, and lysozyme test are all negative. This favors the view that the inflammatory fibroid polyp is fibroblastic in origin.

[Flow cytometric analysis of DNA in esophageal cancer]

Malignancy is the first of the ten leading causes of death in Taiwan area, however, since 1978, esophageal cancer is on the first ten causes of malignancy. Esophageal cancer is an aggressive neoplasm with a generally poor prognosis. This is usually related to the advanced stages of the neoplasm at presentation and at diagnosis. In this study, the DNA content in tumor was analyzed by flow cytometry, and compared it with clinical- pathological data, especially the survival time. All thirty seven cases (36 male, 1 female, mean age: 56.5 +/- 10.3 y/o) received operation at Kaohsiung Medical College Hospital in the past 11 years and 29 cases (27 male, 2 female, mean age: 62.2 +/- 9.6 y/o) proved to be esophageal cancer by endoscopic biopsy were assayed in this study. The formalin fixed-paraffin embedded block is used to analyze DNA content by flow cytometry. After comparing these results with clinical-pathological data, there were no significant difference in sex, age, duration, tumor location and length. However, there is a significant correlation between ploidy and tumor cell differentiation, that is, most of the diploid cells were well differentiated while most of the aneuploid cells were poorly differentiated. The median survival time of diploid cases was 325 days which was longer than the 277 days in aneuploid group, but there was no significant difference between these two groups. The same result was noticed in DNA index. Multiple variables analysis of prognostic factors disclosed that there were significant difference in correation with age tumor location tumor length, and whether there was combined radiotherapy and operation. But there were no significant relationship between survival and DNA ploidy DNA index distant metastasis surrounding tissue invasion sex duration and tumor cell differentiation. These data suggest that DNA folw cytometry analysis alone, may not provide a sueful biologic basis for the variable prognosis seen with esophageal tumors.

Nonspecific DNA binding activity of simian virus 40 large T antigen: evidence for the cooperation of two regions for full activity

We generated a series of COOH-terminal truncated simian virus 40 large tumor (T) antigens by using oligonucleotide-directed site-specific mutagenesis. The mutant proteins [T(1-650) to T(1-516)] were expressed in insect cells infected with recombinant baculoviruses. T(1-623) and shorter proteins [T(1-621) to T(1-516)] appeared to be structurally changed in a region between residues 269 and 522, as determined by increased sensitivities to trypsin digestion and by altered reactivities to several monoclonal antibodies. These same mutant proteins bound significantly less nonorigin plasmid DNA (15%) and calf thymus DNA (25%) than longer proteins [T(1-625) to T(1-708)]. However, all mutant T antigens exhibited a nearly wild-type level of viral origin-specific DNA binding and binding to a helicase substrate DNA. This indicated that binding to origin and helicase substrate DNAs is separable from about 85% of nonspecific binding to double-stranded DNA. As an independent confirmation that a region distinct from the origin-binding domain (amino acids 147 to 247) is involved in nonspecific DNA binding, we found that up to 96% of this latter activity was specifically inhibited in wild-type T antigen by several monoclonal antibodies which collectively bind to the region between residues 269 and 522. In order to investigate the relationship between the origin-binding domain and the second region, we performed origin-specific DNA binding assays with increasing amounts of calf thymus DNA as competitor. The results suggest that this second region is not an independent nonspecific DNA binding domain. Rather, it most likely cooperates with the origin-binding domain to give rise to wild-type levels of nonspecific DNA binding. Our results further suggest that most of the nonspecific binding to double-stranded DNA is involved in a function other than direct recognition and binding to the pentanucleotides at the replication origin on simian virus 40 DNA.

Functional profile of the human fetal gamma-globin gene upstream promoter region

We performed a systematic functional analysis of the human gamma-globin promoter to identify its activator domains. We used a panel of truncation and scanning mutants as well as transfection in human K562 fetal erythroid cells. The various mutations produced relatively small changes in promoter function in both transient and stable transfection assays. The CACCC region and the region containing the binding sites for protein GATA-1 behaved as activator domains. We also obtained evidence for a minor activator site in the - 200 to - 190 region. The results are consistent with the interpretation that gamma-globin gene regulation may occur in part through multiple small effects of promoter elements.

Endoscopy for upper gastrointestinal bleeding at emergency unit

From November 1, 1990 to January 31, 1991, 381 patients visited our emergency unit with the chief complaints of hematemesis (n = 153) and melena (n = 228). Of these patients, 298 (78.2%) received UGI endoscopy at the emergency unit, 29 (7.6%) received examination after they were admitted to wards, 3 (0.8%) received endoscopy at outpatient clinic and 51 (13.4%) did not have endoscopy. The percentages of endoscopic diagnoses in 330 patients who had UGI endoscopy were gastric ulcer (GU) 33.6%, duodenal ulcer (DU) 32.7%, esophageal varices (EV) 17.0%, and others 15.5%. Negative findings were noted in 3 cases and no definite bleeding source was found in 1 patient who had blood retention in stomach. The diagnostic rate of endoscopy was 98.8%. Of the 56 patients with EV, 45 (80.4%) had hematemesis; in contrast, 85 of the 108 DU patients (78.8%) complained of melena only. Of the 219 patients with bleeding GU/DU, 64 (29.2%) had endoscopic therapies and 7 (3.2%) needed operation. Sixty-four (29.2%) of them received UGI endoscopy within 6 hours after arrival. They had significantly higher frequency of stigmata of recent hemorrhage (SRH) and more endoscopic therapies than the remaining patients. The overall mortality rate in our patients was 6.0%; the mortality rate in patients with EV was much higher than that of the patients with GU/DU (19.6% vs. 1.8%, P less than 0.001). Of the 23 expired cases, only 11 died of hypovolemic shock. The remaining 12 patients died of deterioration or complications of their underlying diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of isolated anti-HBc seropositivity by ELISA: implications and the role of radioimmunoassay

Hepatitis B virus (HBV) surface antigen (HBsAg) and antibody to HBsAg (anti-HBs) are excellent markers for HBV infection and its immunity. The significance of isolated antibody to HBV core antigen (anti-HBc) seropositivity is not certain. To elucidate this, sera from 638 Chinese adult subjects, aged 18-52 years, seronegative for both HBsAg and anti-HBs, were tested for anti-HBc. Fifty-one (8%) were found to have an isolated anti-HBc seropositivity by ELISA, and all were negative for IgM-anti-HBc. The anti-HBc persisted in all subjects who attended follow-up for hepatitis B vaccination (n = 48) for a period of 8 months. These 48 subjects received 3 doses of hepatitis B vaccine (HB-VAX, 10 micrograms or 20 micrograms) at 0, 1, and 6 months: 72.9% developed a primary anti-HBs response (suggestive of a false-positive anti-HBc seropositivity), 4.2% developed an anamnestic or secondary anti-HBs response, and 22.9% did not develop an anti-HBs response. Increasing the cutoff point of the ELISA or reconfirmation with radioimmunoassay (RIA) reduced only a minor half of the false positives. This low specificity of anti-HBc ELISA/RIA, together with the high rate of anti-HBs response to hepatitis B vaccine, indicates that subjects with isolated anti-HBc seropositivity should be included in vaccination programs.

Evidence of genetic heterogeneity in five kindreds with familial hypertrophic cardiomyopathy

BACKGROUND

Recently, two families with hypertrophic cardiomyopathy have been shown to have mutations in the cardiac beta-myosin heavy chain gene (beta-MHC) located on the long arm of chromosome 14.

METHODS AND RESULTS

We have performed linkage analysis of five newly ascertained pedigrees with more than 50 chromosomal markers detecting polymorphisms. Our findings confirm the linkage to beta-MHC gene locus on chromosome 14 in one family (LOD score, 4.50) and suggest linkage to the same gene in another kindred. Chromosome 14 markers were not linked to the disease gene in the other three kindreds, however, and a test for genetic heterogeneity was statistically significant. Moreover, markers for the beta-MHC gene identified affected individuals who were recombinants with respect to this gene and the disease phenotype in these three kindreds.

CONCLUSIONS

These results provide conclusive evidence that hypertrophic cardiomyopathy in separate families is caused by mutations in disease genes at two or more locations in the genome.

Subclinical hepatocellular carcinoma in Hong Kong Chinese

Of the 208 Chinese patients with histologically proven hepatocellular carcinoma (HCC) seen during a 5-year period, 191 patients presented with symptomatic HCC and 17 patients with asymptomatic HCC (subclinical HCC, SCHCC) being picked up by alpha-fetoprotein (AFP) screening. Compared with the patients with symptomatic HCC, patients with SCHCC had a better performance status (p less than 0.01), higher serum albumin levels (p less than 0.05) and lower alkaline phosphatase levels (p less than 0.01). In those patients with symptomatic HCC, 4.7% were operable and only 2 patients had a tumour diameter of less than 5 cm. In contrast, patients with SCHCC had a higher operability rate (76.5%, p less than 0.0001) and all had a tumour of less than 5 cm in diameter (p less than 0.0001). Patients with SCHCC, most of whom had their tumour resected, had a better long-term survival (p less than 0.0001). We conclude that patients with SCHCC picked up by AFP serosurveillance have a better performance status, higher operability and better prognosis.

Pyrrolizidine alkaloid composition of three Chinese medicinal herbs, Eupatorium cannabinum, E. japonicum and Crotalaria assamica

The pyrrolizidine alkaloid composition of three Chinese herbs, "pei lan", "cheng gan cao" and "zi xiao rong," identified respectively as Eupatorium cannabinum, Eupatorium japonicum (Compositae) and Crotalaria assamica (Leguminosae), were studied by fast atom bombardment mass spectrometry and gas chromatography-electron impact mass spectrometry. Viridiflorine, cynaustraline, amabiline, supinine, echinatine, rinderine and isomers of these alkaloids were found in the Eupatorium species. Monocrotaline was the only pyrrolizidine alkaloid detected in the Crotalaria species.

Endoscopic injection to arrest peptic ulcer hemorrhage: a prospective, randomized controlled trial; preliminary results

Over a period of 10 months, we conducted a prospective randomized controlled trial of endoscopic injection for the arrest of peptic ulcer hemorrhage in 84 patients. We injected pure alcohol (PA, 99.8%), 50% glucose in water (G/W), 3% NaCl solution, and normal saline solution (N/S, controls) to stop bleeding. The ultimate success rates in the four groups were: 81% (17/21) in the PA group, 80% (16/20) in the 50% G/W group, 65.2% (15/23) in the 3% NaCl group, and 80% (16/20) in the N/S group (p greater than 0.05). The volume of blood transfusion (mean +/- s. e. m.) for each patient was 1,200 ml +/- 433 ml in the PA group, 1,130 +/- 356 ml in the 50% G/W group, 1,704 +/- 330 ml in the 3% NaCl group, 1,400 +/- 548 ml in the N/S group (p greater than 0.05). The duration of hospitalization (mean +/- s. e. m.) was 5.7 +/- 1.5 days in the PA group, 3 +/- 1.3 days in the 50% G/W group, 6.1 +/- 1.1 days in the 3% NaCl group, and 5 +/- 1.1 days in the N/S group (p greater than 0.05). No complication of perforation or aspiration pneumonia was observed during hospitalization. We suggest that endoscopic injection with the above solutions be used as the first line of therapeutic endoscopy for arrest of peptic ulcer hemorrhage.

Gastric acid and pepsin hypersecretion in conscious rabbits

In conscious, gastric fistula rabbits, gastric acid and pepsin secretion averaged 4.5 +/- 0.1 mmol/h (1.3 mmol.kg-1.h-1) and 4.9 +/- 0.3 IU/h (1.6 IU.kg-1.h-1), respectively; these values represent approximately 40-50% of maximal output. Basal serum gastrin concentrations averaged 24 +/- 4 pg/ml and did not correlate with basal acid secretion. Atropine and vagotomy incompletely inhibited basal acid secretion (by 84 and 50%, respectively) and completely inhibited 2-deoxy-D-glucose-stimulated gastric acid secretion. Atropine and vagotomy similarly inhibited basal pepsin secretion by 50 and 40%, respectively. Ranitidine decreased acid and pepsin secretion, but as with atropine, inhibition was not complete (73 and 37%, respectively). Although omeprazole did not affect pepsin secretion, omeprazole completely inhibited basal acid secretion and elevated postprandial intragastric pH above 5.0. Conscious, gastric fistula rabbits have the highest basal acid and pepsin output among species commonly studied. Both vagal-cholinergic pathways and histamine drive basal acid and pepsin secretion in the rabbit.

Endoscopic injection of alcohol to stop peptic ulcer hemorrhage. Experience with 115 cases

In a period of 33 months, we performed endoscopic injection with pure alcohol (PA) to try to stop peptic ulcer hemorrhage in 115 patients. The sex ratio (M/F) was 104/11. The average age was 59.5 +/- 1.5 years (mean +/- SEM). Sixty-two patients (53.9%) were in shock before endoscopic injection. Thirty-three (28.7%) had spurting hemorrhage, 31 (27%) oozing hemorrhage, and 51 (44.3%) nonbleeding visible vessels (NBVV). We obtained initial success in 92 patients (80%). Rebleeding episodes occurred in 7 patients (7.6%) within 7 days of endoscopic injection. Five of those who rebled received a second injection with PA and bleeding stopped in three of them. In 88 (76.5%) patients, therapy was ultimately successful. The duration of hospitalization was 5.1 +/- 0.6 days (mean +/- SEM). The total volume of blood transfused was 1450 +/- 192 ml (mean +/- SEM). We conclude that endoscopic injection is an inexpensive, convenient, and effective means for arresting peptic ulcer hemorrhage. It can be used as the first therapeutic approach.

Application of hepatitis B virus (HBV) DNA sequence polymorphisms to the study of HBV transmission

Short sequences in hypervariable regions of the hepatitis B virus (HBV) genome can be used to identify different strains, providing a novel approach to the study of HBV transmission. The nucleotide sequence in positions 2551-2650 (1:EcoRI site) was determined for serum HBV DNA from 96 Chinese children living in Hong Kong and from 38 of their parents. HBV DNA was extracted and sequenced after amplification with the polymerase chain reaction, using as primers oligonucleotides corresponding to two conserved sequences. Among 82 unrelated children, 32 HBV DNA variants were present. One sequence was present in 33 children and 31 variants were found among the other 49. Siblings within each of nine families had the same variant; in three families siblings had different variants. Six of the eight fathers and 28 of the 30 mothers had HBV DNA sequences identical to those of their offspring. A total of 34 variants were found among the 134 individuals. The hypothesis of random assortment of sequences in parents and children was rejected (P less than .00005). Thus, this new approach proves the occurrence of intrafamilial transmission of HBV among Chinese.

A randomised controlled trial of recombinant interferon-gamma in Chinese patients with chronic hepatitis B virus infection

Nineteen Chinese patients with chronic hepatitis B virus (HBV) infection, seropositive for HBV e antigen (HBeAg) and HBV DNA on at least three occasions in 6 months, were randomised to receive either recombinant human interferon-gamma (rIFN gamma) 0.1 mg/m2 intramuscularly thrice weekly for 16 weeks (n = 11) or no anti-viral therapy (controls, n = 8). Five patients in the treatment group and four patients in the control group had persistently elevated serum alanine aminotransferases (ALT) of over two times the upper limit of normal before entering into the trial. rIFN gamma had no or minimal inhibitory effect on serum HBV DNA during treatment and no patient developed e-seroconversion or sustained loss of serum HBV DNA. Hepatitic flare, which occurred in a proportion of patients responding successfully to interferon-alpha (IFN alpha) therapy, was not observed with rIFN gamma treatment. Side-effects included pyrexia and mild headache that showed tachyphylaxis and were well tolerated by all patients. In the control group, one patient with elevated pre-entry serum ALT lost serum HBV DNA and seroconverted to anti-HBe. Another patient with elevated ALT lost serum HBV DNA transiently during therapy. In the dose given, rIFN gamma was safe but had no apparent anti-viral effects in Chinese patients with chronic HBV infection.

The upstream region of the human gamma-globin gene promoter. Identification and functional analysis of nuclear protein binding sites

The promoter of the human gamma-globin gene confers tissue specificity as well as developmental stage specificity to gamma gene expression. Earlier work in our laboratory suggested that a fragment of the gamma-globin promoter between -300 and -137 base pairs upstream of the transcription start site contributed to the developmental specificity of the promoter. In this paper, we have mapped potential regulatory elements within this upstream region of the gamma promoter by a combination of in vitro DNA-protein binding assays and functional determinations of promoter strength in transient expression studies. Four sites between -300 and -130 bind proteins present in nuclear extracts of erythroid and non-erythroid cell lines. Mutation of these binding sites by internal base substitution determined that three of the four influence overall promoter strength in transient assays. We have focused on two protein binding sites, -246 to -212 and -195 to -170, that have been reported to bind erythroid-specific factors. The erythroid binding protein NF-E1 and a ubiquitous octamer protein footprint the -195 to -170 site. While internal mutation of this site did not significantly alter promoter strength, a point mutation at position -175 that is associated with hereditary persistence of fetal hemoglobin increased the activity of a promoter construct 20-fold in erythroid cells. A detailed mutational analysis of this site suggests that NF-E1 binding is necessary but not sufficient for activation of the promoter by the -175 mutation, and we propose that a second protein or co-activator is required. The nucleotides between -246 and -212 appear to bind a complex of at least three proteins, at the core of which is a protein binding to a string of dA:dT residues. This complex also appears to form on the 3' A gamma-globin enhancer, and homologous sites have been identified within the locus activating region of the beta-globin cluster, suggesting that this element may mediate long range interactions with distant regulatory elements.

Effect of recombinant alpha 2 interferon with or without prednisone in Chinese HBsAg carrier children

Ninety Chinese hepatitis B surface antigen (HBsAg) carrier children, aged 2-17 years, positive for hepatitis B e antigen (HBeAg) and hepatitis B virus DNA on at least three occasions in 6 months, were randomized into 3 groups. Thirty children received syrup vitamin B complex as control, 29 received 6 weeks of placebo syrup followed by 16 weeks of recombinant alpha 2b-interferon [intron A (rIFN2b)], 5 x 10(6) u/m2 subcutaneously thrice weekly; and 31 received 6 weeks of syrup prednisone (0.6 mg/kg tailed to 0.2 mg/kg) followed by 16 weeks of recombinant alpha 2b-interferon as above. The placebo/prednisone syrup was given on a double-blind basis. At 24 months of follow-up, persistent loss of hepatitis B virus DNA occurred in none of the children in the control group, in one child receiving recombinant alpha 2b-interferon alone, who also seroconverted to anti-HBe and anti-HBs and in five children receiving interferon with steroid priming (p = 0.0571 compared with controls), with four seroconverting to anti-HBe and one also seroconverting to anti-HBs. A rise of transaminases to above twice the upper limit of normal levels during the first 7 months of follow-up occurred in one subject in the control group, four in the group receiving alpha 2b-interferon alone and nine in the group receiving recombinant alpha 2b-interferon with steroid priming (p = 0.0144 compared with controls). Side effects of the steroid were negligible; those of recombinant alpha 2b-interferon were transient and acceptable. We conclude that 6 weeks of prednisone followed by 16 weeks of recombinant alpha 2b-interferon is of use in inducing persistent loss of hepatitis B virus DNA (16.1 per cent) and e-seroconversion (12.9 per cent) in a proportion of Chinese HBsAg carrier children: the prednisone probably enhances the immunomodulatory effect of recombinant alpha 2b-interferon.

The Two-Step Hydrolysis of Dimethoxo(tetraphenylporphyrinato)tin(IV)

The hydrolysis of dimethoxo ( tetraphenylporphyrinato )tin(IV), Sn ( tpp )( OMe )2 was studied by n.m.r. spectroscopy. The use of specially dehydrated CDCl3 allowed the hydrolysis intermediate hydroxomethoxo (tetraphenylporphyrinato )tin(IV) Sn ( tpp )( OMe )(OH), to be identified. The results show that the second step, of the two-step hydrolysis, is rate limiting.

Inheritance of Resistance to Crown Gall in Pisum sativum

We screened a total of 1365 pea (Pisum sativum) lines for response to inoculation with Agrobacterium tumefaciens, strain B6, and characterized resistance in one cultivar, Sweet Snap. Sweet Snap seedlings were highly resistant to tumorigenesis under most conditions. Resistance was overcome at inoculum concentrations of greater than 10(9) bacteria per milliliter. At such high concentrations, very small tumors developed on Sweet Snap in response to four wide-host-range Agrobacterium strains, but tumors on other cultivars were two-to sevenfold larger than those that formed on Sweet Snap. The hypervirulent strain A281 induced larger tumors on Sweet Snap than did other Agrobacterium strains, but tumors on other genotypes were more than 100% larger than those on Sweet Snap. Physiological experiments suggested that tumorigenesis in Sweet Snap is not blocked in early stages of infection, and genetic analysis indicated that inheritance of resistance to crown gall is a quantitative trait. In addition to the observed resistance in Sweet Snap, three ;supersusceptible' genotypes, which developed very large tumors, also were identified.

Genetics of common diseases of adulthood. Implications for prenatal counseling and diagnosis

Genetic factors play an important role in the development of many common diseases of adulthood that result in early morbidity and mortality. Prevention of these disorders and their sequelae is best established through early detection and early intervention. Although it may be feasible to screen the entire population for some disorders (e.g., hypertension), this approach would be expensive and impractical for others (e.g., colon cancer). The family history provides an inexpensive and convenient method of identifying families at risk for premature diseases of adulthood. Family screening for a disorder should be recommended if there is increased risk for the disorder among family members, if screening methods are available to detect the condition at an early age or preclinical stage, and if early intervention will alter the course of the disease. For many disorders screening and intervention can prevent the occurrence of clinical disease. The prenatal counseling session affords an ideal setting for identifying families at risk for diseases of adulthood with major genetic components. By reviewing the family history, key family members can be identified and investigated, in order to establish a specific genetic diagnosis. At-risk relatives can then be counseled and screened for the disorder preclinically and premorbidly. The screening and intervention available for a disease depends on the nature of the disorder, our understanding of its physiology and etiology, and our current technology. The disorders discussed earlier are typical of conditions of adulthood that are influenced strongly by genetic factors, especially when they appear in younger adults. Atherosclerosis, colon cancer, and diabetes are complex phenotypes. Each can be caused by single-gene defects, but commonly the genetics are more complex. Empiric data help to establish the risk to an individual in the latter cases. In all three examples, early detection should lead to treatment, which can prevent more serious sequelae: by treating the dyslipidemia, coronary artery disease can be prevented; by removing the benign polyp, malignant cancer can be avoided; and when impaired glucose tolerance is detected, diet and exercise can prevent or delay frank diabetes and its complications. The complete evaluation of individuals at risk for disorders such as those in Table 1 and their families can be a complicated task. Referral to a center experienced in the genetics of common diseases often may be necessary.(ABSTRACT TRUNCATED AT 400 WORDS)

Correlation of Pectolytic Enzyme Activity with the Programmed Release of Cells from Root Caps of Pea (Pisum sativum)

In many plant species, the daily release of hundreds to thousands of healthy cells from the root cap into the soil is a normal process, whose function is unknown. We studied the separation of the cells in pea (Pisum sativum) using an aeroponic system in which separated cells were retained on the root until they were washed off for counting. We found that cell separation is a developmentally regulated, temperature-sensitive process that appears to be regulated independently of root growth. No cells were released from very young roots. When plants were grown aeroponically, cell numbers increased with increasing root length to a mean of 3400 cells per root, at which point the release of new cells ceased. The process could be reset and synchronized by washing the root in water to remove shed cells. Cell separation from the root cap was correlated with pectolytic enzyme activity in root cap tissue. Because these cells that separate from the root cap ensheath the root as it grows and thus provide a cellular interface between the root surface and the soil, we propose to call the cells "root border cells."

Purification and characterization of a DNA polymerase from the cyanobacterium Anacystis nidulans R2

A DNA polymerase has been highly purified from Anacystis nidulans R2. Electrophoretic analysis in sodium dodecyl sulfate-polyacrylamide gels revealed that the final fraction contains three bands of Mr 107,000, 93,000, and 51,000, respectively. Analysis of purified DNA polymerase activity in situ indicates that of the three polypeptides the Mr 107,000 species has the catalytic activities. The native molecular weight of the enzyme was estimated by glycerol gradient sedimentation to be 100,000. The enzyme has an absolute requirement for a divalent cation. Mg2+ can be replaced with Mn2+, but the DNA polymerase is less active. Potassium chloride stimulates the enzyme, while potassium phosphate has no apparent effect. The enzyme is active over a pH range from 7.5 to 9.5 in 50mM Tris-HCl buffer. The ability of the cyanobacterial DNA polymerase to use activated DNA as a template, its associated 3'----5' and 5'----3' exonuclease activities, as well as its resistance to N-ethylmaleimide, dideoxynucleotides, arabinosyl-CTP and aphidicolin suggest a similarity between this enzyme and E. coli DNA polymerase I. This is the first characterization of a DNA polymerase from a cyanobacterium.