Deconstructing sex: Strategies for undoing binary thinking in neuroendocrinology and behavior.

The scientific community widely recognizes that "sex" is a complex category composed of multiple physiologies. Yet in practice, basic scientific research often treats "sex" as a single, internally consistent, and often binary variable. This practice occludes important physiological factors and processes, and thus limits the scientific value of our findings. In human-oriented biomedical research, the use of simplistic (and often binary) models of sex ignores the existence of intersex, trans, non-binary, and gender non-conforming people and contributes to a medical paradigm that neglects their needs and interests. More broadly, our collective reliance on these models legitimizes a false paradigm of human biology that undergirds harmful medical practices and anti-trans political movements. Herein, we continue the conversations begun at the SBN 2022 Symposium on Hormones and Trans Health, providing guiding questions to help scientists deconstruct and rethink the use of "sex" across the stages of the scientific method. We offer these as a step toward a scientific paradigm that more accurately recognizes and represents sexed physiologies as multiple, interacting, variable, and unbounded by gendered preconceptions. We hope this paper will serve as a useful resource for scientists who seek a new paradigm for researching and understanding sexed physiologies that improves our science, widens the applicability of our findings, and deters the misuse of our research against marginalized groups.

The distribution of small and intermediate conductance calcium-activated potassium channels in the rat sensory nervous system.

Small (SK) and intermediate (IK) conductance calcium-activated potassium channels are candidate ion channels for the regulation of excitability in nociceptive neurones. We have used unique peptide-directed antisera to describe the immunocytochemical distribution of the known isoforms of these ion channels in dorsal root ganglia (DRG) and spinal cord of the rat. These investigations sought to characterize further the phenotype and hence possible functions of nociceptive neurone subpopulations in the rat. In addition, using Western blotting, we sought to determine the level of protein expression of SK and IK channels in sensory nervous tissues following induction of inflammation (Freund's Complete Adjuvant (FCA) arthritis model) or nerve injury (chronic constriction injury model). We show that SK1, SK2, SK3 and IK1 are all expressed in DRG and spinal cord. Morphometric analysis revealed that SK1, SK2 and IK1 were preferentially localized to neurones having cell bodies <1000 microm2 (putative nociceptors) in DRG. Dual labeling immunocytochemistry showed that these ion channels co-localize with both CGRP and IB4, known markers of nociceptor sub-populations. SK2 was localized almost exclusively in the superficial laminae of the spinal cord dorsal horn, the region in which many sensory afferents terminate; the distribution of SK1 and IK1 was more widespread in spinal cord, although some preferential labeling within the dorsal horn was observed in the case of IK1. Here we show evidence for a distinctive pattern of expression for certain members of the calcium-activated potassium channel family in the rat DRG.

Vitamin requirements: present recommendations and future prospects.

Dietary recommendations evolved from instructions directed at prevention of starvation diseases to the level of intake of essential nutrients that are adequate to meet the known nutrient needs of practically all healthy persons. Vitamin requirements have been modified various times over the years and there are still differences in recommended intakes in different countries. A debate on optimal vitamin intake is ongoing, based on the concepts of deficiency, sufficiency and hypothetical identification of a range within which a further biological advantage can be expected. In establishing appropriate criteria for food and nutrient intakes, additional studies are warranted on the physiological interactions between nutrients and non-nutrients and on many other factors such as genetic determinants and lifestyle which could interfere with disease prevention.

Fat, fish, fish oil and cancer.

There is an ecological association between total and animal fat consumption and colorectal and breast cancer risk. Mortality data for breast and colorectal cancer for 24 European countries correlated, as expected, with the consumption of animal, but not vegetable, fat. There was an inverse correlation with fish and fish oil consumption, when expressed as a proportion of total or animal fat, and this correlation was significant for both male and female colorectal cancer and for female breast cancer, whether the intakes were in the current time period, or 10 years or 23 years before cancer mortality. These effects were only seen in countries with a high ( > 85 g caput-1 day-1) animal fat intake. This evidence suggests that fish oil consumption is associated with protection against the promotional effects of animal fat in colorectal and breast carcinogenesis.

Fish, n-3 fatty acids and human colorectal and breast cancer mortality.

Although there is a strong positive association between total fat consumption and colorectal and breast cancer risk, there is evidence that n-3 fatty acids, mainly found in fish oil, are protective. If this is so, we would expect to be able to detect an inverse correlation between fish consumption and colorectal cancer and breast cancer mortality. Mortality data for breast and colorectal cancer in 24 European countries were correlated with current fish and fish oil consumption and with consumption 10 and 23 years previously. In males there was an inverse correlation between colorectal cancer mortality and current intake of fish (P = 0.036), a weaker correlation with fish consumption 10 years earlier (P = 0.042) and none with consumption 23 years earlier (P = 0.12). The data were not statistically significant in females. There was no correlation at all between breast cancer mortality and fish or fish oil consumption at any time. It is concluded that fish consumption is associated with protection against the later promotional stages of colorectal carcinogenesis, but not with the early initiation stages. The results are discussed in terms of the role of prostaglandins in colorectal carcinogenesis.

Effect of ascorbic acid on the intragastric environment in patients at increased risk of developing gastric cancer.

Ascorbic acid has been shown to decrease nitrosation in vivo, and epidemiological data suggest that the consumption of foods rich in this vitamin is associated with a reduced risk for gastric cancer. In order to study this suggestion further, fasting gastric juice samples were obtained from 62 high-risk patients (seven with atrophic gastritis, ten with pernicious anaemia, ten with partial gastrectomy, 21 with vagotomy and drainage and 14 with highly selective vagotomy), before, during four weeks' treatment with 1 g ascorbic acid four times daily, and four weeks after treatment. Samples were analysed for pH, total and nitrate-reducing bacterial counts, nitrite and N-nitroso compounds. Treatment with ascorbic acid lowered the median pH only in the vagotomized patients (p less than 0.001) but resulted in a reduction in median nitrate-reducing bacterial counts and in nitrite and N-nitroso compound concentrations in all groups, except for an increase in the nitrate-reducing bacterial count in atrophic gastritis patients and in nitrite in those with pernicious anaemia. These data suggest that treatment with a high dose of ascorbic acid reduces the intragastric formation of nitrite and N-nitroso compounds.

Dietary modification of potential vitamin K supply from enteric bacterial menaquinones in rats.

Rats given a low-fibre diet based on boiled white rice developed symptoms of severe vitamin K deficiency within 23 d. Inclusion of autoclaved black-eye beans (Vigna unguiculata) in the diet prevented the bleeding syndrome. To test the hypothesis that deficiency resulted from low phylloquinone intake exacerbated by inadequate production of menaquinones by the enteric bacteria, a follow-up experiment was carried out in which groups of rats were given an all-rice diet, a rice + beans diet or a stock diet. Rats on the all-rice diet had significantly lower faecal concentrations of the main menaquinone-producing bacterial species (Bacteroides fragilis and Bacteroides vulgatus) than animals on either of the other two diets. This coupled with the much lower faecal output on this diet suggests that total menaquinone production was low for the all-rice diet. The alterations in faecal flora were associated with several significant changes in caecal metabolism. Rats given the stock diet had much shorter caecal transit times and a considerably greater proportion of butyric acid in volatile fatty acid end-products than did rats on either of the other two diets.

Serum selenium and gastric cancer in two regions of Norfolk.

Selenium concentrations were measured in the serum of 244 patients attending the Norfolk and Norwich Hospital, and 246 attending the James Paget Hospital in Gorleston, Norfolk. Both the mean and the median serum selenium concentration was lower in Gorleston than in Norwich, the difference being much greater in women than in men. Whereas the selenium concentrations were normally distributed about the mean for the Norwich area, there was a skewed distribution for the Gorleston area. The results are discussed in relation to the previously observed high risk of intestinal type gastric cancer in the Gorleston area.

The digestion of pectin in the human gut and its effect on calcium absorption and large bowel function.

1. The effect of dietary fibre digestion in the human gut on its ability to alter bowel habit and impair mineral absorption has been investigated using the technique of metablic balance. 2. Five healthy male students were studied for 9 weeks under controlled dietary conditions and during the last 6 weeks they took 36 g pectin/d. Bowel habit, transit through the gut, faecal fibre excretion, calcium balance and faecal composition were measured. 3. During the control period only 15% of the dietary fibre ingested was excreted in the stools and when pectin was added to the diet there was no increase in fibre excretion. Stool frequency and mean transit time were unchanged by pectin but stool wet weight increased by 33% and faecal excretion increased (%) for fatty acids 80, nitrogen 47, total dry matter 28 and bile acids 35. Ca balance remained unchanged. 4. It may be concluded from these results that dietary fibre is largely metabolized in the human gut and dietary pectin completely so. This could explain its lack of effect on bowel habit and Ca balance. Other changes in the faeces may be related to an increase in bacterial mass.

Changes in fecal composition and colonic function due to cereal fiber.

The effect on colonic function of adding wheat fiber for 3 weeks to the metabolically-controlled diets of six healthy volunteers has been studied. Increasing dietary fiber intake from 17 to 45 g/day increased fecal weight from 79 +/- 6.6 g/day to 228 +/- 29.9 g/day and shortened mean transit time, measured by a continuous marker method, from 57.8 +/- 8.3 hr to 40.3 +/- 8.9 hr. The increase in fecal weight was largely due to water. Fiber caused a dilution of fecal marker and an increase in fecal fat, nitrogen, and calcium output. Fecal sodium, potassium, and chloride showed only small changes but volatile fatty acid output increased significantly without concentrations changing. Fecal bile acid output increased from 199 +/- 46 mg/day to 279 +/- 46 mg/day. These changes are discussed in light of current views of the role of dietary fiber in protecting against colon cancer.

Metabolic responses to dietary supplements of bran.

During a metabolic ward study, the addition of dietary fiber in the form of wheat bran biscuits to the diet of five volunteer subjects resulted in an increase in the stool wet weight and fecal solids. The excretion of fecal solids was highly correlated with the intake of unavailable carbohydrates, and fecal losses of water were similarly correlated with fecal excretion of these constituents. The major component of the increase in fecal solids was due to the noncellulosic polysaccharide fraction of dietary fiber. There was an increased fecal excretion of nitrogen fat and energy by most subjects when the supplement was eaten. However, the increased loss of energy in the feces was only 40-80 kcal/day, and therefore a large supplemental intake of dietary fiber had only minor effects on energy metabolism. Supplemental fiber is thus unlikely to induce a useful loss of calories in the management of obesity. The addition of dietary fiber caused an increased excretion of most inorganic constituents, particularly sodium and phosphorus; increased excretion of iron and magnesium was also found in two subjects.

Effects of two types of dietary fibre on faecal steroid and lipid excretion.

Fibre supplements from wheat bran and sugar cane residue (bagasse) were added to the normal diet of volunteers for 12-week periods in a controlled metabolic study. Stool weights and stool fat excretion increased on both dietary fibres. Bagasse increased the daily loss of acid steroids, but bran failed to affect bile acid excretion. Decreased transit time without alteration in faecal flora occurred with bagasse. The raised excretion of bile acids and fatty acids failed to lower the plasma cholesterol and triglycerides after 12 weeks. Thus different fibre sources with variable components have dissimilar metabolic effects.