The use of compound heterozygotes and Hprt selection to analyze X-linked mottled alleles associated with prenatal lethality

X-linked mutant alleles associated with prenatal male lethality are difficult to analyze because only heterozygous females are readily available for study. Genomic analysis of the mutant allele is facilitated by the construction of somatic cell hybrids because this enables the segregation of the X Chromosomes (Chrs) that carry the mutant and wild-type alleles. We describe here a method that ensures that the X Chr carrying the mutant allele is retained in somatic cell hybrids in an active selectable state. This is achieved by mating heterozygous females to males that carry a mutation at the hypoxanthine phosphoribosyl transferase (Hprt) locus. The resultant F1 females are compound heterozygotes, and when cells from these females are fused to HPRT- Chinese hamster cells and subjected to selection in HAT medium, the only survivors are those hybrid cells that retain an active X Chr carrying the mutant allele together with the wild-type Hprt allele. We use hybrids constructed by this method to demonstrate that there are no gross deletions or genomic rearrangements present in three mottled alleles associated with prenatal male lethality.

An accessory protein enhances both DNA binding and activity of DNA polymerase alpha isolated from normal, but not transformed, human fibroblasts

DNA polymerase alpha/primase (pol alpha) isolated from fibroblasts established from a 66-year-old human donor (GM3529) exhibited decreased specific activity compared with pol alpha from either fetal-derived fibroblasts (WI38), or pSV3.neo-transformed GM3529 fibroblasts. The pol alpha specific activity decrease was correlated with a decreased proliferative capacity frequently seen in cells from aged donors. Pol alpha isolated from pSV3.neo-transformed GM3529 cells (GM3529T) exhibited a single isoform with about 10-fold higher specific activity than pol alpha from GM3529 cells. GM3529T pol alpha was immunoreactive with both anti-pol alpha and anti-SV40 large tumor antigen. Polymerases from GM3529 and GM3529T cells were treated with a pol alpha accessory protein, alpha AP, isolated from L1210 cells. Pol alpha from GM3529T cells showed no increase in activity in the presence of alpha AP, while pol alpha isolated from GM3529 cells exhibited about an 8-fold increase in activity after treatment with alpha AP. Double stranded SV40 DNA containing multiple ori sequences exhibited a greater decrease in electrophoretic mobility in the presence of GM3529T pol alpha than when treated with GM3529 pol alpha. In the presence of pol alpha from either GM35229 or GM3529T cells SV40 dsDNA exhibited a decrease in electrophoretic mobility, and in each instance addition of alpha AP resulted in an even greater decrease in DNA mobility. These data indicate that alpha AP increased pol alpha binding to SV40 dsDNA, or that alpha AP bound the DNA in addition to previously bound pol alpha. GM3529 pol alpha also bound non-specific, non-SV40, dsDNA, whereas GM3529T pol alpha with associated TAg did not bind the non-viral dsDNA unless alpha AP was added to the preparation. While not all human diploid fibroblast cell lines derived from aged human donors necessarily exhibit decreased proliferative capacity compared with cells from young donors, decreased specific activity associated with a decline in cellular DNA synthesis is typical of pol alpha from cells derived from aged human donors. We suggest that a decrease in endogenous alpha AP interaction with pol alpha may account, in part, for the loss of DNA binding affinity and specific activity of pol alpha from GM3529 cells derived from an aged donor.

Genetics of gastric cancer

Although the death rate from gastric carcinoma in the US and other western communities has decreased in recent times, a similar trend has not been noted in other countries, especially S.E. Asia. Upto 95% of all malignant gastric neoplasms are adenocarcinomata, but other types of gastric cancer have evoked considerable interest in the literature. Genetic factors have been suspected of playing a pivotal role in the etiology of gastric cancer but no clear inheritance pattern has emerged and environmental influences remain the focus of many current theories of pathogenesis. Current evidence implicates the non-random involvement of certain chromosomes and related oncogenes especially Ras and p53. Genes that may predispose to gastric cancer have not been clearly implicated but some studies indicate a familial aggregation of gastric cancer. The objective of this review is to reappraise the role of genetics in the etiology of gastric cancer with special reference to relevant information for practicing clinicians.

Crude oil spill in sea water: an assessment of the risk for bathers correlated to benzo(a)pyrene exposure

In the spring of 1991, there was a shipwreck of the oil tanker "Haven" off the Ligurian coast of Italy. This resulted in the spillage of a very large amount of crude oil, some of which was burned off by fire. The accident caused several serious problems (sea and air pollution, damage to the marine fauna, risk of human exposure, etc.). In this context, an assessment was carried out at the Istituto Superior di Sanità with the aim of determining any possible risks to humans which might derive from bathing activities during the following summer season. The whole evaluation carried out after the accident demonstrated that the impacts induced were not serious enough to require bathing restrictions in the coastal areas involved. Assuming a benzo(a)pyrene (BaP) concentration in sea water of 1 microgram/m3 cancer risk is in the order of 10(-8) and in the case of 10-kg child, a 10(-6) risk level correspond to about 0.18 microgram/l of BaP in sea water.

Sequence analysis of the breakpoint regions of an X;5 translocation in a female with Duchenne muscular dystrophy

X;autosome translocations in females with Duchenne muscular dystrophy (DMD) provide an opportunity to study the mechanisms responsible for chromosomal rearrangements that occur in the germ line. We describe here a detailed molecular analysis of the translocation breakpoints of an X;autosome reciprocal translocation, t(X;5)(p21;q31.1), in a female with DMD. Cosmid clones that contained the X-chromosome breakpoint region were identified, and subclones that hybridized to the translocation junction fragment in restriction digests of the patient's DNA were isolated and sequenced. Primers designed from the X-chromosomal sequence were used to obtain the junction fragments on the der(X) and the der(5) by inverse PCR. The resultant clones were also cloned and sequenced, and this information used to isolate the chromosome 5 breakpoint region. Comparison of the DNA sequences of the junction fragments with those of the breakpoint regions on chromosomes X and 5 revealed that the translocation arose by nonhomologous recombination with an imprecise reciprocal exchange. Four and six base pairs of unknown origin are inserted at the exchange points of the der(X) and der(5), respectively, and three nucleotides are deleted from the X-chromosome sequence. Two features were found that may have played a role in the generation of the translocation. These were (1) a repeat motif with an internal homopyrimidine stretch 10 bp upstream from the X-chromosome breakpoint and (2) a 9-bp sequence of 78% homology located near the breakpoints on chromosomes 5 and X.

Metastatic squamous cell carcinoma of the hand and review of the literature

New cases of cancer amongst medical workers arising as a result of X-ray exposure are now rare. We record a case of a dentist who presented 11 years ago with a radiation induced squamous cell carcinoma of the ring finger of his left hand with massive axillary lymphadenopathy. Repeated exposure of his hands to diagnostic dental irradiation in his surgery had lead 16 years previously to a troublesome radiodermatitis which had been mistakenly diagnosed and had itself been treated with radiotherapy without effect. Management by amputation of the distal phalanx of the ring finger, debulking of the axillary lymphadenopathy with adjunctive radiotherapy to the axilla and chemotherapy, have been successful in achieving a prolonged disease free interval and satisfactory hand function.

Acid suppression and gastric mucosal cell biology

This review examines recent concepts of gastric mucosal cell biology in relation to acid inhibition. Powerful acid-inhibitory drugs have been associated with the production of enterochromaffin-like (ECL) cell proliferation and the induction of ECL-cell carcinoids in rats. The ECL-cell lineage and its renewal is discussed, and the factors that regulate ECL-cell proliferation are reviewed. Current methods in use for assessing genotoxicity in gastric mucosa are scrutinized; the much discussed claim that antisecretory drugs induce unscheduled DNA synthesis is examined, and the methodology that is the basis for these claims is found defective and wanting. The nature of ECL-cell proliferation in rats receiving lifelong treatment with H2-receptor antagonists or acid pump inhibitors is explored, and their relationship to ECL-cell proliferation and ECL-cell carcinoids discussed. It is concluded that aged rats are very prone to developing endocrine proliferations, and this may be related to the multiple endocrine neoplasia syndrome found in humans. There is no evidence at present that long-term antisecretory therapy causes significant ECL-cell proliferation in humans.

Ablation of neoplasia by direct current

The application of low-voltage direct electrical current (DEC) has been studied in animals and humans for the ablation of anal condylomata, oesophageal cancer and Kaposi's sarcoma. Twenty milliamps of DEC passed through multiple 6 cm x 1 cm, flat-plate longitudinal electrodes into the squamous mucosa of the oesophagus of healthy dogs for periods ranging from 10 min to 2 h resulted in denudation and necrosis of the oesophageal mucosa at the site of application of the current. In humans, the application of DEC to two patients with benign anal condyloma acuminata, three patients with inoperable obstructing oesophageal cancer and one patient with disseminated Kaposi sarcoma resulted in striking necrosis of tumour tissue that was confirmed by macroscopic and microscopic studies. These initial findings imply promising therapeutic potential for the use of DEC as a simple, effective, safe, low-cost alternative for ablation of neoplasia.

Severe adenoviral nephritis following bone marrow transplantation: successful treatment with intravenous ribavirin

Invasive adenovirus infection is recognized as an unusual cause of serious end-organ sequelae following BMT. Because symptomatic therapy may be inadequate for more serious infections, the use of investigational agents is justified. We describe a case of severe, progressive nephritis secondary to adenovirus serotype 11 following BMT. Treatment with i.v. ribavirin led to prompt clinical improvement and resolution of adenovirus excretion.

Nonsteroidal antiinflammatory drugs and lower gastrointestinal bleeding

To define the association of the ingestion of nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin (ASA), and lower gastrointestinal bleeding (GIB) a retrospective, case-controlled study was undertaken of 188 patients admitted to three community hospitals in three cities with a diagnosis of lower GIB. Information was obtained about NSAID usage among these patients, and the data were compared with an age- and sex-matched control group of 185 patients admitted with a nongastrointestinal diagnosis, derived from a daily admission list. At the time of admission, in the New Jersey group, NSAID consumption was present in 26 of 90 (29%) patients with lower GIB compared with 16 of 90 (18%) of controls (P < 0.05, odds ratio 1.88, 95% CI 1.2-3.1) whereas, in the South Carolina group 34 of 98 (35%) were taking NSAID compared with 18 of 95 (19%) of controls (P < 0.01, odds ratio 2.27, 95% CI 1.2-4.4). These data indicate that there is a significantly increased rate of NSAID ingestion in patients admitted with lower GIB, implying that NSAID may unmask bleeding from a variety of lower gastrointestinal lesions.

Chronic pancreatitis

Chronic pancreatitis is caused most often by chronic excessive alcohol consumption. The disease can be diagnosed by investigations that measure function or assess morphology of the pancreas, thereby permitting a tailored management approach. In many patients, abdominal pain and steatorrhea can be managed effectively by enzyme supplementation, provided such supplements are administered in appropriate formulations and doses. Definition and correction of mechanical problems are possible by modern endoscopic approaches, and surgery plays an important role in the management of local and regional complications of the disease.

Lack of prognostic significance of DNA ploidy and S phase fraction in breast cancer

DNA Ploidy and S phase fraction (SPF) were measured in Stage I and II breast cancers from patients with at least 8 years of follow-up, to assess the prognostic significance of these data. Disaggregated sections of formalin-fixed, paraffin-embedded tumour were analysed by flow cytometry. SPF was calculated using a rectangular model of S phase, after subtraction of background debris using an exponential model. 64% of tumours were DNA aneuploid. The median SPF was 4.5% for DNA diploid, and 10.9% for DNA aneuploid tumours. There were small reductions in survival at 10 years for DNA aneuploid tumours, and for tumours with above median SPF, but these were not statistically significant. The relative hazard for DNA aneuploid tumours was 1.20 (95% CI 0.81-1.76), and for high SPF was 1.31 (95% CI 0.87-1.98). Neither factor was statistically correlated with survival in multivariate analysis. Technical and theoretical factors limit the accuracy and reproducibility of flow cytometric data, and may explain the lack of prognostic information given.

Computer assessment of life-style in a gastroenterology clinic

To examine the potential benefit of a computer-assisted interview about life-style in gastroenterology practice, 34 consecutive patients attending a gastroenterology clinic were questioned by a computer using software designed to obtain a comprehensive history of alcohol, caffeine, cigarette, and illicit drug use, together with an assessment of exercise, sexual activity, and nutrition. Comparisons of the information obtained by the computer with clinical records revealed that physicians documented only 3% of the patients as problem drinkers, 3% as caffeine abusers, and 17% as smokers, whereas the computer identified 10% of the patients as problem drinkers, 27% as caffeine abusers, and 43% as smokers. These findings imply that patients may be more apt to tell more about adverse life-style to the computer than to a physician during clinical interview. In a sample patient population from a gastroenterology clinic, a microcomputer provides an acceptable, efficient, and potentially cost-effective way to assess life-style.

Gastroesophageal physiology after stapled gastroesophagostomy in dogs

A stapled vertical gastroesophagostomy (VGE) has been proposed for benign esophageal stricture. The VGE involves performing an anastomosis using a linear cutting stapler inserted via a gastrotomy (one limb in the esophagus, the other in the proximal fundus). In phase I of the study, a 50-mm VGE was performed in 13 dogs; 7 received an additional fundoplication. Endoscopy with pinch biopsies, esophageal manometry, and 4-hour ambulatory pH recordings were performed in each dog prior to and 1 month after VGE. The only difference between groups postoperatively was a higher lower esophageal sphincter pressure in the group with the added fundoplication. The incidence of histologic esophagitis was low in both groups. In phase II of the study, a VGE was performed in six dogs using a 75-mm linear cutting stapler, accompanied by fundoplication in each dog. These dogs were then followed for 6 months to more completely assess the long-term risk of developing reflux esophagitis. At necropsy, no gross or histologic evidence of esophagitis was found. The performance of a VGE through the lower esophageal sphincter in normal dogs does not result in significant reflux esophagitis. VGE may be an alternative to resection for esophageal stricture.

Comparison of Nissen total and Lind partial transabdominal fundoplication in the treatment of gastro-oesophageal reflux

Fifty-two patients with gastro-oesophageal reflux disease refractory to medical treatment were randomized to undergo a Nissen total (360 degrees wrap) or Lind partial (300 degrees wrap) transabdominal fundoplication. Each group was comparable in number (26 patients), mean age (47 and 48 years) and sex distribution (eight women). Preoperative and postoperative assessment involved a modified Visick score, 22-h intraoesophageal pH monitoring, endoscopy and manometry. Follow-up was at 6 weeks and between 3 and 33 (mean 13) months. The prevalence of heartburn and regurgitation and the results of pH monitoring improved significantly after both operations (P less than 0.001). At early assessment eight previously asymptomatic patients (31 per cent) from the Nissen group and six (23 per cent) from the Lind group experienced difficulty swallowing. Ten patients (38 per cent) in each group complained of 'gas bloat'. Both complications had improved at late assessment in the majority of patients. No statistically significant advantage could be demonstrated for either operation.

Relationship of satiety to postprandial glycaemic, insulin and cholecystokinin responses

The effect of plasma glucose on satiety and the capacity of carbohydrates to stimulate cholecystokinin (CCK) remain unclear. The aim of this study was to test the hypothesis that the magnitude of the postprandial plasma glucose and insulin response is inversely related to the CCK response and to subjective satiety. Seven healthy, male volunteers consumed equal carbohydrate portions (0.5 g/kg body weight) of six test meals (Rice Bubbles, Sustain, Vita-Brits, All-Bran, porridge and white bread) in random order after an overnight fast. An egg and bacon meal was consumed as a non-carbohydrate control providing 0.5 g protein/kg body weight. Serum CCK, plasma glucose and insulin and subjective satiety (measured by a rating scale) were assessed over 3 h and quantified using the glycaemic index (GI), insulin index (II), the peak satiety score and area under the incremental curve (AUC). The observed GIs (mean +/- SE) ranged from 42.5 +/- 2.6 for All-Bran to 116.2 +/- 11.4 for Rice Bubbles, using white bread as the reference food (GI = 100). Peak satiety scores varied eightfold from 0.21 +/- 0.4 for Sustain to 1.64 +/- 0.4 for All-Bran. Significant inverse relationships were observed between the peak satiety score and both the glycaemic and insulin index of the seven meals (r = -0.916, p less than 0.001 and r = -0.926, p less than 0.001). A direct relationship was observed between satiety (AUC) and the CCK response (AUC) (r = 0.73 p less than 0.01). The results suggest that glycaemic and insulin responses to carbohydrate foods are inversely proportional to the CCK response and satiety.

Barrett's esophagus: observations on diagnosis and management

Barrett's esophagus is a premalignant condition that may often pass unrecognized in clinical practice. In adults, this condition is generally believed to be caused by chronic gastroesophageal reflux resulting in a metaplastic change in the epithelium of the esophagus. Diagnosis of Barrett's esophagus is established by careful biopsy of the involved esophageal mucosa. Periodic surveillance is recommended because of the risk of carcinoma. Antireflux surgery has not been shown to result consistently in the regression of the metaplastic epithelium, but potent acid suppression offers a new therapeutic approach that leads to healing of esophagitis and the potential regression of Barrett's epithelium.

Long-term prognostic significance of thymidine labelling index in primary breast cancer

Tumour growth rates, as measured by incorporation of tritiated thymidine, have been reported as being of prognostic importance in breast cancer. We have measured the thymidine labelling index (TLI) of 185 early breast cancers, followed-up for a minimum of 8 years. Above median TLI was associated with higher tumour grade, but not with other prognostic factors. TLI was not predictive of survival in either univariate or multivariate analysis. The inter- and intra-observer reproducibilities of TLI measurements were poor, which may be a factor limiting its usefulness as a prognostic indicator in breast cancer.

Two doses of omeprazole versus placebo in symptomatic erosive esophagitis: the U.S. Multicenter Study

Two hundred thirty patients with reflux symptoms and endoscopically proven erosive esophagitis were enrolled from 15 U.S. centers into a randomized, double-blind, dose-ranging study comparing placebo with omeprazole, 20 or 40 mg given once daily in the morning. Esophagitis grade 2 was present in 44% of patients, grade 3 in 37% of patients, and grade 4 in 19% of patients. Endpoints, defined as complete relief of heartburn and complete esophageal mucosal healing, were assessed after 4 and 8 weeks of treatment. Both omeprazole doses were significantly superior to placebo in complete endoscopic healing. After 8 weeks of treatment, 73.5% of patients in the 20-mg omeprazole group and 74.7% in the 40-mg omeprazole group, compared with 14.0% in the placebo group, had complete healing of the esophageal mucosa. At the end of the study, complete relief of daytime heartburn was obtained in 79.5% of patients in the 20-mg omeprazole group, 81.6% in the 40-mg omeprazole group, and 37.2% in the placebo group (P less than or equal to 0.05). Complete relief of nighttime heartburn was noted by 79.5% of patients in the 20-mg omeprazole group, 85.1% in the 40-mg omeprazole group, and 34.9% in the placebo group (P less than or equal to 0.05). The median time to complete relief of daytime and nighttime heartburn occurred earlier in the 40-mg group than in the 20-mg group (9 vs. 17 days and 9 vs. 20 days, respectively); however, these differences were not statistically significant. Relief of acid regurgitation and dysphagia also occurred earlier in the 40-mg group. Omeprazole was well tolerated in this group of patients. No unexpected adverse experiences occurred. The results of this study confirm those of six multicenter, international trials in which omeprazole in doses of 20-60 mg provided a degree of esophageal mucosal healing and complete relief of reflux symptoms superior to any other medical treatment.