Experimental Biology and Medicine

Polycystic ovary syndrome (PCOS) usually arises during puberty and is marked by hyperinsulinemia and hyperandrogenism. Adolescents with PCOS are at an increased risk of developing health problems later on in life such as type 2 diabetes, cardiovascular disease, and infertility. Furthermore, the physical signs of PCOS can be detrimental to a teenage girl's self-image. Early diagnosis and treatment of PCOS in adolescents are essential in ensuring adulthood health and restoring self-esteem. Treatments for an adolescent with PCOS include diet and exercise, metformin, and oral contraceptive pills. Each of these options has been shown to be effective in improving certain aspects of PCOS, and probably the best treatment plan involves some combination of them.

Radiobiologists have been struggling to estimate the health risks from low doses of radiation in humans for decades. Health risks involve not only neoplastic diseases but also somatic mutations that may contribute to other illnesses (including birth defects and ocular maladies) and heritable mutations that may increase the risk of diseases in future generations. Low dose radiation-induced cancer in humans depends on several variables, and most of these variables are not possible to correct for in any epidemiologic study. Some of the confounding factors include (i) interaction of radiation with other physical (UV light), chemical, and biological mutagens and carcinogens in a synergistic manner; (ii) variation in repair mechanisms that depend on dose; (iii) variation in sensitivity of bystander cells to subsequent radiation exposure that depends on whether they have been pre- or postirradiated; and (iv) variation in adaptive response that depends on radiation doses and protective substances (antioxidants). In our opinion, both the linear no-threshold-response and the threshold-response models might not be suitable in predicting cancer risk at low radiation doses in a quantitative sense. Low doses of ionizing radiation should not be considered insignificant for risks of somatic and heritable, mutations and neoplastic and nonneoplastic diseases in humans.

Cadmium (Cd²⁺) is a common environmental pollutant and a major constituent of tobacco smoke. Exposure to this heavy metal, which has no known beneficial physiological role, has been linked to a wide range of detrimental effects on mammalian reproduction. Intriguingly, depending on the identity of the steroidogenic tissue involved and the dosage used, it has been reported to either enhance or inhibit the biosynthesis of progesterone, a hormone that is inexorably linked to both normal ovarian cyclicity and the maintenance of pregnancy. Thus, Cd²⁺ has been shown to exert significant effects on ovarian and reproductive tract morphology, with extremely low dosages reported to stimulate ovarian luteal progesterone biosynthesis and high dosages inhibiting it. In addition, Cd²⁺ exposure during human pregnancy has been linked to decreased birth weights and premature birth, with the enhanced levels of placental Cd²⁺ resulting from maternal exposure to industrial wastes or tobacco smoke being associated with decreased progesterone biosynthesis by the placental trophoblast. The stimulatory effects of Cd²⁺ on ovarian progesterone synthesis, as revealed by the results of studies using stable porcine granulosa cells, appear centered on the enhanced conversion of cholesterol to pregnenolone by the cytochrome P450 side chain cleavage (P450scc). However, in the placenta, the Cd²⁺-induced decline in progesterone synthesis is commensurate with a decrease in P450scc. Additionally, placental low-density lipoprotein receptor (LDL-R) mRNA declines in response to Cd²⁺ exposure, suggesting an inhibition in the pathway that provides cholesterol precursor from the maternal peripheral circulation. Potential mechanisms by which Cd²⁺ may affect steroidogenesis include interference with the DNA binding zinc (Zn²⁺)-finger motif through the substitution of Cd²⁺ for Zn²⁺ or by taking on the role of an endocrine disrupting chemical (EDC) that could mimic or inhibit the actions of endogenous estrogens. Divergent, tissue-specific (ovary vs. placenta) effects of Cd²⁺ also cannot be ruled out. Therefore, in consideration of the data currently available and in light of the potentially serious consequences of environmental Cd²⁺ exposure to human reproduction, we propose that priority should be given to studies dedicated to further elucidating the mechanisms involved.

There is significant interest in the use of mushrooms and/or mushroom extracts as dietary supplements based on theories that they enhance immune function and promote health. To some extent, select mushrooms have been shown to have stimulatory action on immune responsiveness, particularly when studied in vitro. However, despite their widespread use for potential health benefits, there is a surprising paucity of epidemiologic and experimental studies that address the biologic activities of mushrooms after oral administration to animals or humans. There have been a number of studies that have addressed the ability of mushrooms to modulate mononuclear cell activation and the phenotypic expression of cytokines and their cognate receptors. There have also been a number of attempts to determine antitumor activities of mushrooms. Such studies are important because many of the components of mushrooms do potentially have significant biologic activity. All data, however, should be tempered by the Possibility that there are toxic levels of metals, including arsenic, lead, cadmium, and mercury as well as the presence of radioactive contamination with ¹³⁷Cs. In this review, we will Present the comparative biology with respect to both immunological and antitumor activities of mushroom extracts and also highlight the need for further evidence-based research.

We recently postulated that hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase functions as a cholesterol buffer to protect against the serum and tissue cholesterol raising action of dietary cholesterol. This postulate predicts that diminished basal expression of hepatic HMG-CoA reductase results in increased sensitivity to dietary cholesterol. Because diabetic and hypothyroid animals are known to have markedly reduced hepatic HMG-CoA reductase, these animals were selected as models to test our postulate. When rats were rendered diabetic with streptozotocin, their hepatic HMG-CoA reductase activity decreased from 314 to 22 pmol • min^-1 • mg^-1, and their serum cholesterol levels increased slightly. When the diabetic animals were challenged with a diet containing 1% cholesterol, their serum cholesterol levels doubled, and their hepatic reductase activity decreased further to 0.9 pmol • min^-1 • mg^-1. Hepatic low-density lipoprotein (LDL) receptor immunoreactive protein levels were unaffected in the diabetic rats whether fed cholesterol-supplemented diets or not. In rats rendered hypothyroid by thyroparathyroidectomy, serum cholesterol levels rose from 100 to 386 mg/dl in response to the 1% cholesterol challenge, whereas HMG-CoA reductase activity dropped from 33.8 to 3.4 pmol • min^-1 • mg^-1. Hepatic LDL receptor immunoreactive protein levels decreased only slightly in the hypothyroid rats fed cholesterol-supplemented diets. Taken together, these results show that rats deficient in either insulin or thyroid hormone are extremely sensitive to dietary cholesterol largely due to low basal expression of hepatic HMG-CoA reductase.

The premise that the intrinsic level of expression of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase determines the relative sensitivity to the serum cholesterol raising action of dietary cholesterol was examined in 9 strains of rat. For further comparison purposes, hamsters were also examined. The basal expression of hepatic HMG-CoA reductase, extent of feedback regulation by cholesterol, and changes in serum cholesterol levels and the hepatic low-density lipoprotein (LDL) receptor in response to cholesterol challenge were determined in these animals. The Sprague-Dawley, Wistar-Furth, Spontaneously Hypertensive, Lewis, and Wistar-Kyoto rats were all very resistant to dietary cholesterol and exhibited hepatic HMG-CoA reductase activities above 150 pmol/min^-1 / mg^-1. The Buffalo, Brown Norway, and Copenhagen 2331 rats had hepatic HMG-CoA reductase activities below 90 pmol / min^-1 / mg^-1 and had increases in serum cholesterol levels ranging from 12 to 33 mg/dl when given a 4-day, 1% cholesterol challenge. The extent of feedback regulation was reduced to only 3-fold in the Fisher 344 and Brown Norway rats that exhibited significant increases in serum cholesterol levels when given a cholesterol challenge. The Golden Syrian hamsters exhibited the largest increase (197 mg/dl) in serum cholesterol levels in response to dietary cholesterol and the lowest basal expression of hepatic HMG-CoA reductase (3.3 pmol / min^-1 / mg^-1). Hepatic LDL receptor levels were not significantly decreased by dietary cholesterol in any of the animals. The data from these inbred rats and the hamsters strongly support the conclusion that the animals expressing the highest levels of hepatic HMG-CoA reductase are the most resistant to the serum cholesterol raising action of dietary cholesterol.

Hydroxymatairesinol (HMR), obtained from the heartwood of spruce (Picea abies), has been demonstrated to exert chemopreventive effects on the development of mammary tumors in rats. To examine the influence of HMR on uterine carcinogenesis, adult Donryu rats were initiated with a single intrauterine treatment of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) at 11 weeks of age and fed thereafter 0, 200, or 600 ppm HMR mixed in the soy-containing diet until 15 months of age. Incidences of uterine adenocarcinoma in both 200 and 600 ppm HMR-dosed groups were significantly reduced to 11% and 15%, respectively, less than 50% of 0 ppm, at the end of the experiment (P < 0.05). A delay in the start of persistent estrus by HMR was observed at 8 months of age compared with controls given carcinogen alone. From urinalysis, HMR was metabolized mainly to enterolactone and hydroxyenterolactone. These findings suggest that HMR or its metabolites exert chemopreventive effects in the rat ENNG-uterine carcinogenesis model.

This laboratory has reported that multiple low doses of streptozotocin (MLD-STZ) similarly upregulate the T helper (Th)1-type proinflammatory cytokines tumor necrosis factor (TNF)-α and interferon (IFN)-γ in islets of both the diabetes-susceptible male and the diabetes-resistant female C57BL/6 mice and that MLD-STZ downregulates the anti-inflammatory Th2-type cytokines interleukin (IL)-4 and IL-10, as well as the anti-inflammatory Th3-type cytokine-transforming growth factor (TGF)β1 in islets of male, but not female, mice. Thus, diabetes is associated with a relative preponderance of local proinflammatory cytokines. Here, we investigated the effects of MLD-STZ on the anti-inflammatory cytokine IL-11 and the transcription factors nuclear factor (NF)-κB and activator protein (AP)-1, which are involved in gene activation of proinflammatory cytokines, and on the cytosolic kinase (IKK-α) of NF-κB inhibitor (IκB). Furthermore, the effect of recombinant human (rh)IL-11 on MLD-STZ diabetes, insulitis, cytokines, IKK-α, NF-κB, and AP-1 was analyzed in islets.

Interleukin-11 prevented diabetes without affecting insulitis; attenuated TNF-α and IFN-γ response; and stimulated IL-4 production and inhibited activation of IKK-α, NF-κB, and AP-1. The results demonstrated the potential of rhIL-11 in preventing MLD-STZ diabetes through enhancement of anti-inflammatory responses in islets. In this process, the transcription factors NF-κB and AP-1 might play a key role.