Induction of cytochrome P(1)450 RNA and benzo[a]pyrene metabolism in primary human hepatocyte cultures with benzanthracene.

Exposure of cells to microsomal enzyme inducers can modify the potency of many carcinogens. We have examined the steady-state level of RNA from the P(1)450 gene and the metabolism of benzo[a]pyrene (BP) in primary cultures of human hepatocytes exposed for up to 4 days to 12.5 microM benzanthracene (BA), and in uninduced control cultures. While the steady-state levels of RNA from the P(1)450 gene were nondetectable in uninduced (DMSO only) human hepatocytes, 12.5 microM BA-induced AHH activity, BP metabolism, and/or P(1)450-specific RNA in hepatocytes from seven human cases were investigated. RNA levels specific for the P(1)450 gene appeared maximal at 24 hr following exposure to BA, whereas, the protein, as determined by AHH enzyme activity from BA-induced hepatocytes, continued to increase up to the last time point examined, 72 hr. BA induction for 96 hr increased metabolism of BP (initial concentration of BP, 10 microM) over a time course of 3, 6, 12, and 24 hr of incubation with BP compared with that of controls. The major metabolites of BP produced by human hepatocytes in culture were the unidentified polar BP metabolite(s), possibly polyhydroxylated. BA induction caused approximately a twofold increase in these metabolites. BA-induced cultures showed an increase in glutathione conjugation compared to that in controls. The percentage of glucuronide and sulfate conjugates remains similar in all cultures. Total binding of tritium label BP to DNA was 1.3-fold to fivefold greater in induced cultures, and related more to total metabolism than to production of a specific metabolite. Exposure of human hepatocytes in vitro to BA leads to a large increase in the steady-state level of the RNA specific for the P(1)450 gene and an increase metabolism of BP.     

ANEURYSMAL BONE CYST IN THE MANDIBLE (A Case Report)

Aneurysmal bone cyst is commonly seen in the long bones and vertebrae and is rare in the jaws. Its association with other lesions of the bone has been stressed by many workers. Because of its variable radiological appearance, diagnosis of the lesion is established by histopathological examination. A case of aneurysmal bone cyst occurring in the mandible is reported.KEY WORDS: Aneurysmal bone cyst, Mandible     

Safety of incidental appendectomy

Reports in the surgical literature are conflicting as to whether appendectomy "in passing" during laparotomy for trauma or for some other disease state does or does not significantly increase patient morbidity or mortality. A chart survey of all appendectomies (342 for acute appendicitis and 146 as incidental procedures) performed on the trauma service of Grady Memorial Hospital over a 40 month period appeared to indicate that the wound infection rate (6.8 percent) was the same as that for acute simple or suppurative appendicitis (6.7 percent), whereas the intraabdominal sepsis rate (17.5 percent) paralleled that for more advanced gangrenous or perforative appendicitis (18.6 percent). Since the validity of a retrospective review is always open to question, a prospective, randomized trial was carried out only on patients with a negative abdominal exploration for trauma over a 22 month interval at the same trauma service. An odd second from the last digit hospital number dictated appendectomy, provided the appendix was readily accessible; an even digit in the same locus dictated retention of the appendix. In no patient did intraperitoneal sepsis develop, regardless of the procedure chosen. Wound infection rates were 1.8 percent for appendectomy (1 of 56), if local anatomic considerations precluded an easy appendectomy (0 of 45), and 3.6 percent for the control subjects without appendectomy (3 of 83). There were no deaths. These data cast considerable doubt on the reliability of retrospective reviews and support the generally accepted dictum that incidental appendectomy, especially in the trauma patient, can be a relatively innocuous procedure.     

Comparisons of the effects of chemical carcinogens in mixed cultures of rat hepatocytes and human fibroblasts

Unscheduled DNA synthesis (UDS) was measured simultaneouslyin rat hepatocytes and human fibroblasts when combined culturesof the 2 cell types were exposed to procarcinogens. Human fibroblastswere preincubated with 5-bromo-2'-deoxyuridine (BRdU) to substitutefor thymidine in the DNA. Hepatocyte DNA was separated fromthe heavier BRdU-substituted fibroblast DNA by isopycnic centrifugationsin neutral cesium chloride and the specific activities of theDNA's were determined. In the presence of hepatocytes, benzo[a]pyrene(BP) induced more UDS in the fibroblasts than in the hepatocytes.BP induced no UDS in the fibroblasts in the absence of hepatocytes.Diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) stimulateda significant amount of UDS only in the hepatocytes. Thus, theco-cultures of hepatocytes and fibroblasts responded with UDSto these chemical carcinogens in a manner that parallels thetissue specificity of the carcinogenicity of these chemicalsin vivo. That is, the known hepatocarcinogens DEN and AAF, onlystimulated significant UDS in the hepatocytes, whereas the non-hepatocarcinogen,BP, though activated in these cultures mainly by the hepatocytes,stimulated more UDS in the fibroblasts than in the hepatocytes.The amount of [³H]BP bound to DNA was investigated in the co-culturesand in cultures of fibroblasts alone. When co-cultures wereexposed to [³H]BP the fibroblast DNA had approximately 3 timesmore BP bound to it (per µg DNA) than did the hepatocyteDNA. The amount of [³H]BP bound to the DNA of cultures of fibroblastsalone was 29% of the amount bound to the DNA of the fibroblastsfrom the co-cultures. Thus, although the hepatocytes were mainlyresponsible for the activation of BP, more [³H]BP was boundto the fibroblast DNA. It is suggested that the intercellulardistribution of carcinogenic metabolites may be a significantdeterminant of the carcinogenic effect.     

Accuracy of Preimplantation Diagnosis of Single-Gene Disorders by Polar Body Analysis of Oocytes

Purpose: A number of pitfalls in single-cell DNA analysis, including undetected DNA contamination, undetected allele drop out, and preferential amplification, may lead to misdiagnosis in preimplantation genetic diagnosis of single-gene disorders. Methods: Preimplantation genetic diagnosis was performed by sequential first and second polar body analysis of oocytes in 26 couples at risk for having children with various single-gene disorders. Mutant genes were amplified simultaneously with linked polymorphic markers, and only embryos resulting from the mutation-free oocytes predicted by polar body analysis with confirmation by polymorphic marker testing were transferred back to patients. Results: Overall 529 oocytes from 48 clinical cycles (26 patients) were tested, resulting in the transfer of 106 embryos in 44 clinical cycles. As many as 46 (9.6%) instances of allele dropout were observed, the majority (96%) of which were detected. Seventeen unaffected pregnancies were established, of which nine resulted in the birth of an unaffected child, and the rest are ongoing. Conclusions: A high accuracy of preimplantation genetic diagnosis of single-gene disorders is achieved by application of sequential analysis of the first and second polar body and multiplex polymerase chain reaction.     

Limiting the location of a putative human prostate cancer tumor suppressor gene at chromosome 13q14.3

We studied loss of heterozygosity (LOH) on human chromosome 13q in prostate cancer specimens to determine the location of a putative tumor suppressor gene (TSG) and to correlate these losses with the clinicopathological stage of the disease. Overall 13 (21%) of 61 specimens analysed had an allele loss on the long arm of chromosome 13. The most frequent (37%) LOH among the informative cases with allele losses was detected at the D13S284 locus on chromosome 13q14. 3. A portion of the DNA segment that spans this locus and is flanked by the microsatellite loci D13S153 and D13S163 was lost in 85% of the specimens with allele losses and was designated as a LOH cluster region (LCR). The LCR spans more than 6 Mbp of DNA. The results suggest that a TSG relevant for the development of prostate cancer is located telomeric to the RB locus. There was a significant correlation (P=0.0024) between chromosome 13q LOH and advanced metastatic disease, suggesting that loss of 13q14.3 region is associated with prostate cancer progression. However, further research must be conducted to establish the identity and function of this putative TSG.     

Prevalence and causes of hypergastrinemia in primary hyperparathyroidism: a prospective study

Gastrin levels have been reported to be often increased in patients with primary hyperparathyroidism (PHPT) considered to be caused by hypercalcemia. To determine the prevalence of increased basal gastrin and to investigate its causes, 52 consecutive patients with PHPT were studied prospectively, undergoing a clinical, biochemical, and gastric morphofunctional assessment before any parathyroid surgical procedure. This included evaluation of basal and secretin-stimulated gastrin, basal and pentagastrin-stimulated gastric acid secretion, upper gastrointestinal endoscopy, with histological evaluation for gastritis and Helicobacter pylori infection. Twenty of the 52 PHPT patients (38.5%) had increased fasting gastrin. Further investigation allowed us to clearly demonstrate the causes of hypergastrinemia in 16 of these 20 patients. In 7 of 20 (35%), hypergastrinemia was caused by gastric fundus atrophy; in 3 patients (15%), Zollinger-Ellison syndrome with Multiple Endocrine Neoplasia type I was diagnosed; whereas in another 20% of patients, mild hypergastrinemia was ascribed to Helicobacter pylori gastritis. Finally, in 2 patients, additional clinical history revealed an occasional use of the gastric antisecretory drug omeprazole a few days before the serum gastrin determination. This study shows that the hypercalcemic status per se is not sufficient to produce an increase in fasting gastrin levels. Furthermore, gastric fundus atrophy, and not gastrinoma, is the major cause of relevant (>160 pg/mL) hypergastrinemia.