Diet, physical activity, and colorectal cancer among Chinese in North America and China

In a population-based case-control study of colorectal cancer among Chinese men and women in western North America and the People's Republic of China, a common protocol was used to assess past life-style characteristics of 905 cases diagnosed during 1981-1986 and 2,488 controls. Risks for cancers of both the colon and rectum increased with increased food energy from fat, protein, carbohydrate, and all energy sources combined, for both sexes and on both continents. Yet, in multivariate analysis, colorectal cancer risk was significantly associated only with saturated fat; no relationships were seen with other dietary sources of energy. Colon cancer risk was elevated among men employed in sedentary occupations. On both continents and in both sexes, risks for cancers of both the colon and rectum increased with increasing time spent sitting. Further, the association between colorectal cancer risk and saturated fat was stronger among the sedentary than among the active. Risk among sedentary Chinese Americans of either sex increased more than fourfold from the lowest to the highest category of saturated fat intake. Among migrants to North America, risk increased with increasing years lived in North America. These observations suggest (a) that colorectal cancer risk increases with duration of exposure to a sedentary life-style and a diet rich in saturated fat; (b) that higher incidence among Chinese-American men relative to women is due to longer duration of these habits among men, who have lived longer in North America; and (c) that higher risk among Chinese Americans of both sexes relative to risk among the general population in China is due to differences in such habits. Attributable risk calculations suggest that, if these associations are causal, saturated fat intakes exceeding 10 g/day, particularly in combination with physical inactivity, could account for 60% of colorectal cancer incidence among Chinese-American men and 40% among Chinese-American women.

[Sedative-hypnotic effect of caulis Polygoni multiflori decoction]

The sedative-hypnotic effect of Caulis Polygoni multiflori decoction (CPMD) was studied by the rolling cylinder method in mice and by the somnopolygraphic recording method in rats. The result from the rolling method in mice showed that CPMD (9g/kg) did have synergic action with the subthreshold hypnotic dose of sodium pentobarbital (20mg/kg). The result from the somnopolygraphic recording experiment showed that the immediate hypnotic effect of an effective dose of CPMD (20g/kg) was basically similar to that of diazepam (5mg/kg) used under the same experimental condition, chiefly an increase in the duration of slow wave sleep phase (SWS) and a decrease in the duration of paradoxical sleep phase (PS). By the end of a three-day session in dose of twice a day the hypnotic effect appeared more prominent and the reduction of SWS latency became significant.

KIH-802, an acetohydroxamic acid derivative of 2-nitroimidazole, as a new potent hypoxic cell radiosensitizer: radiosensitizing activity, acute toxicity, and pharmacokinetics

The radiosensitizing activity, acute toxicity, and pharmacokinetics of a new hypoxic cell radiosensitizer, potassium 2-nitroimidazole-1-acetohydroxamate (KIH-802), were compared with those of misonidazole (MISO) and etanidazole (SR-2508). The radiosensitizing activity of KIH-802 was slightly higher than that of MISO and SR-2508 in vitro and was similar to or slightly higher than that of MISO or SR-2508 in vivo. The acute toxicity of KIH-802 was slightly higher than that of MISO. The concentrations of KIH-802 in the brains and peripheral nerves of mice were as low as those of SR-2508 and lower than those of MISO.

A family of positive regulators related to the Pseudomonas putida TOL plasmid XylS and the Escherichia coli AraC activators

The XylS family consists of a least 8 different transcriptional regulators. Six of these proteins are positive regulators for the catabolism of carbon sources (benzoate and sugars) in Escherichia coli, Pseudomonas putida and Erwinia carotovora, and two of them are involved in pathogenesis in Escherichia coli and Yersinia enterocolitica. Based on protein alignments, the members of this family exhibit a long stretch of homology at the C-terminal end. The regulators involved in the catabolism of carbon sources stimulate transcription from their respectively regulated promoters only in the presence of effectors. In two of the regulators, mutations at the non-homologous N-terminus alter affinity and specificity for effectors while mutations at the conserved C-terminus part decrease activation of transcription from their corresponding regulated promoters. It is thus probable that the variable N-terminus end in this family of regulators contains the motif involved in effector recognition, while the C-terminal end is involved in DNA-binding. These proteins seem to be related by common ancestry and may act through similar mechanisms of positive regulation effected through similar folding patterns.

Supplementary iodine fails to reverse hypothyroidism in adolescents and adults with endemic cretinism

The efficacy of supplemental iodine in correcting hypothyroidism in adults and older children with endemic myxedematous cretinism is not known. To investigate this issue we administered im iodized oil (1.5 mL) to 28 hypothyroid endemic cretins (TSH, greater than 5 mIU/L) from western China, aged 14-52 yr (mean = 29 SD = 11 yr). Clinical examination, intelligence testing (Hiskey Nebraska Test of Learning Aptitude and the Griffiths Mental Development Scales), and thyroid function tests were performed before and 6 months after iodine supplementation. We found that signs of thyroid hormone deficiency, dwarfism, and delayed sexual maturity persisted after iodine supplementation. Further, mental disability and other clinical features of neurological damage were not altered by treatment. The mean serum concentration of total T4 before treatment was 75 nmol/L (SD = 40) and fell after iodized oil administration to 56 nmol/L (SD = 29; P less than 0.001). Mean serum levels of TSH before and after iodine showed a paradoxical fall [85 mIU/L (SD = 102) and 46 mIU/L (SD = 46), respectively]. Serum TSH levels decreased into the normal range (less than 5 mIU/L) in only 1 of 28 patients (4%). We conclude that iodine supplementation does not reverse thyroid hormone deficiency or its sequelae in adolescents and adults with endemic myxedematous cretinism. Iodized oil in this age group of patients with endemic cretinism does not appear to be beneficial and should be used with caution.

An important role of endogenous insulin on exocrine pancreatic secretion in rats

We have investigated a physiological role of endogenous insulin on exocrine pancreatic secretion stimulated by a liquid meal as well as exogenous secretin and cholecystokinin octapeptide (CCK-8) in conscious rats. Each rat was prepared with a chronic pancreatic fistula and an indwelling catheter in a jugular vein. Oral ingestion of a liquid meal (5 ml) resulted in significant increases in pancreatic secretion, including volume, bicarbonate, and amylase output, in these rats. A rabbit anti-insulin serum (1.0 ml) given intravenously completely blocked the postprandial exocrine pancreatic secretion, whereas a normal rabbit serum did not influence the pancreatic secretion in the same rats. When pancreatic secretion was stimulated by intravenous administration of both secretin and CCK-8 in three different doses, including 0.015, 0.03, and 0.06 clinical unit and microgram.kg-1.h-1, respectively, volume, bicarbonate, and amylase output increased significantly in a dose-dependent manner. This increase in pancreatic secretion was also completely blocked by a rabbit anti-insulin serum, whereas it was not influenced by a normal rabbit serum. The amount of the antiserum employed abolished the postprandial increases in plasma insulin concentration. We conclude that endogenous insulin plays an important role on the regulation of postprandial pancreatic secretion in rats. Furthermore, for the stimulatory action of the two intestinal hormones secretin and CCK-8 on the pancreatic exocrine secretion, endogenous insulin is need.

[Short-term curative effect of cultured Cordyceps sinensis (Berk.) Sacc. Mycelia in chronic hepatitis B]

33 cases of chronic hepatitis B. patients treated with cultured Cordyceps sinensis mycelia have shown that the drug improves the liver function, promotes negative transfer HBsAg, and markedly helps to raise plasma albumin, resist high gamma globulin and to adjust body immunocompetence. It is therefore suggested that cultured Cordyceps sinensis mycelia may be used as a medicine for chronic hepatitis B. patients in adjusting protein metabolism and correcting inversion of albumin and globulin.

[Effects of CCK-8 of hypothalamus on antral motility in rats]

Cholecystokinin-octapeptide (CCK-8) of 10 ng were injected into lateral hypothalamus (LH) and ventromedial hypothalamus (VMH) in conscious rats, both of which brought about inhibition of antral motility recorded by a strain gauge, the actions were partly antagonised by bilateral vagotomy, but blocked by intravenous infusion of atropine or regitine. It is suggested that both vagus and sympathetic nerves be involved in mediation of function of central CCK-8. In addition, the unit spontaneous discharges of neurons in vagal nuclei were attenuated while CCK-8 injected into LH. On the contrary, the antral motility was stimulated markedly by injection CCK-8-antiserum into LH, indicating that the endogenous CCK-8 in this area exercises a continuous restraint on antral motility in the basal state. CCK-8 cells both in LH and VMH were visualized by PAP method. It may be reasonable to refer this as the histological basis of the identical function on antral motility exercised by CCK-8 both in LH and VMH.

[Inhibition of gastric acid secretion by vascularly perfused secretin and somatostatin in isolated rat stomach]

Effects of secretin and somatostatin on acid secretion and its relation to prostaglandin E, I2 release in the totally isolated vascularly perfused rat stomach were studied. The results showed: (1) Secretin and somatostatin both markedly inhibited acid secretion stimulated by pentagastrin. Indomethacin could reverse the inhibitory effects of acid secretion by secretin and somatostatin. (2) Secretin increased PGE and PGI2 metabolite 6-Keto-PGF1 alpha release significantly. Somatostatin only increased PGE release. Indomethacin could block stimulatory affects of secretin on PGE, 6-Keto-PGF1 alpha release and somatostatin on PGE release. These results indicated that: (1) inhibition of acid secretion by secretin was mediated by PGI2 and PGE release; (2) inhibition of acid secretion by somatostatin was mediated only by PGE release.

A new, potent 2-nitroimidazole nucleoside hypoxic cell radiosensitizer, RP170

The radiosensitizing activity, acute toxicity and pharmacokinetics of RP170, a new hypoxic cell radiosensitizer, were compared with those of misonidazole (MISO) and SR2508. RP170 belongs to the group of 2-nitroimidazole nucleosides, which are designed to be selectively excluded from the neural tissue. The reduction potential of RP170 was similar to that of MISO and SR2508. The partition coefficients in octanol/water of RP170, MISO, and SR2508 were 0.094, 0.35, and 0.021, respectively. The radiosensitizing activity of RP170 was similar to that of MISO and SR2508 in vitro and in vivo. There was no significant difference in the radiosensitizing activity of RP170 in vivo between intravenous and intraperitoneal administration. The acute toxicity of RP170 was the same as that of SR2508. Pharmacokinetic evaluation showed that the concentration of RP170 in the brain was as low as that of SR2508. RP170 is expected to have the same radiosensitizing effects as MISO and SR2508, and to be less neurotoxic than MISO.

[Multinucleated giant cells in cultured giant cell tumor of bone]

Further observations on multinucleated giant cells (MGCs) in 12 giant cell tumors of bone (GCT) were made, by means of tissue culture, electron microscopy and immunohistochemistry. In continuous in vitro culture, two distinct types of MGCs were found and herein termed preliminarily short-lived MGCs and long-lived MGCs respectively. The former type had limited life span of about 2-3 weeks, whereas the latter type of MGCs maintained growth or continual formation. They had entirely different appearance and characteristics. This fact reflects two types of MGCs exist in GCT in vivo. Besides, the origin of MGCs were also investigated and discussed in considerable depth.

Contrast study on multinucleated giant cells in giant cell tumors of bone and other multinucleated cells

By means of tissue culture, electron microscopy, cytochemistry, indirect immunofluorescence and immunohistochemistry, the multinucleated giant cells(MGCs) in 12 giant cell tumors of bone (GCT) were studied in contrast with osteoclasts (OCs), foreign body giant cells (FGCs) and inflammatory giant cells (IGCs). The findings in the majority of MGCs were identical with those in OCs, suggesting that they most probably derived from the same precursor. Continuous in vitro culture revealed two kinds of MGCs, which were designated preliminarily as short-lived MGCs and long-lived MGCs for their difference in morphology and in several biological features, which suggests two kinds of MGCs exist in GCT. We conclude that the short-lived conform to the typical MGCs known generally to the pathologists, while the long-lived are deemed to be closely related to the neoplastic elements of the tumor.

A retrovirus vector which transduces a functional estrogen receptor gene at high efficiency

A high titer retroviral vector containing the cDNA of human estrogen receptor (hER) was generated and used to transfer the hER gene into the rat 208F cell line. Southern blot analysis showed the integration of the provirus to be at a unique site and that the provirus was intact in the genome of recipient cells. The expression of the integrated hER gene in the infected rat cells was detected by Northern blot analysis and by a functional assay in which the hER gene product stimulated the production of a chloramphenicol acetyl transferase gene under the control of an estrogen-responsive element. These experiments demonstrate the feasibility of using a retroviral vector system to introduce a functional ER gene into cultured cells lacking this receptor.

Characteristics of fluorinated nitroazoles as hypoxic cell radiosensitizers

Types of 2-nitroimidazoles and 3-nitro-1,2,4-triazoles bearing one or two fluorine atoms on their side chains were synthesized to evaluate their physicochemical properties, radiosensitizing effects, and toxicity. The reduction potential of the compounds containing one fluorine was similar to that of misonidazole (MISO), whereas that of the difluorinated compounds was slightly higher. Both mono- and difluorinated compounds had an in vitro sensitizing activity comparable to or slightly higher than that of MISO. The fluorinated 3-nitrotriazoles were almost as efficient as the 2-nitroimidazoles with the same substituent. In vivo, some of the compounds were up to twice more efficient than MISO, whereas others were as efficient as MISO. Toxicity in terms of LD50/7 in mice was quite variable depending on the side-chain structure; the amide derivatives were less toxic than MISO, whereas the alcohol and ether derivatives were more toxic. In view of the radiosensitizing effect and toxicity in vivo, at least one compound, KU-2285 (a 2-nitroimidazole with an N1-substituent of: CH2CF2CONHCH2CH2OH) has been found to be as useful a hypoxic cell sensitizer as SR-2508.

Importance of tumor affinity of nitroazoles in hypoxic radiosensitization

In vitro and in vivo sensitizing activities of a variety of nitroazole derivatives including misonidazole (MISO), SR-2508, and RSU-1069 were correlated by the aid of pharmacokinetic measurements of the drug uptake in animal solid tumors. The sensitizer enhancement ratio in vivo (SERvivo) on solid tumors increased linearly with the square root of administrated dose (Ds). The specific activity (A) in vivo of nitroazoles was evaluated from the square-root empirical relationship, SERvivo = 1.00 + A D1/2S. The intratumor concentration of nitroazoles at a given time t after administration was in proportion to the DS, in which the proportional constant was defined as the tumor-affinity factor FT,t. The absolute molar activity alpha M defined by A(M/FT,t)1/2, where M is the molecular weight of nitroazoles, showed a linear relationship with the SER in vitro (SERvitro) at 1 mM of sensitizers. The sensitizer dose required to achieve an SERvivo of 1.5 (DS,1.5) decreased and thus the overall sensitizing efficiency on animal solid tumors increased as the FT,t became greater.

[Antidotal effect of Stenoloma chusanum(L.) Ching against arsenic and ammonium]

The antidotal effect of four extracts from Stenoloma chusanum on acute poisoning of mice caused by arsenic and ammonium chloride was observed. The result shows: extracts B and C can reduce the mortality of mice remarkably, while extract C can raise the tolerance of mice by raising their LD50 from 31.1 +/- 4.3 mg/kg to 38.2 +/- 5.9 mg/kg. In the case of the mice poisoned by ammonium chloride, the four extracts can also reduce the mortality, but make no significant difference as compared with the control group statistically (P greater than 0.05).

New Evidence on the Size and Possible Effects of a Late Pliocene Oceanic Asteroid Impact

Debris from a late Pliocene asteroid impact is spread across at least 600 kilometers of the ocean floor in the southeast Pacific. On the basis of iridium concentrations in sediments from six deep-sea cores, the asteroid diameter was at least 0.5 kilometer; the impacting projectile may have been one of the largest in the last few million years. The stratigraphic age of this impact is the same as that inferred for the onset of Northern Hemisphere glaciation.