COVID infection in 4 steps: Thermodynamic considerations reveal how viral mucosal diffusion, target receptor affinity and furin cleavage act in concert to drive the nature and degree of infection in human COVID-19 disease.

We have developed a mechanistic model of SARS-CoV-2 and SARS-CoV infection, exploring the relationship between the viral diffusion in the mucosa and viral affinity for the angiotensin converting enzyme 2 (ACE2) target. Utilising the structural similarity of SARS-CoV and SARS-CoV-2 and a shared viral target receptor (ACE2), but a dramatic difference in upper or lower respiratory tract infectivity, we were able to generate insights into the linkage of mucosal diffusion and target receptor affinity in determining the pathophysiological pathways of these two viruses. Our analysis reveals that for SARS-CoV-2 the higher affinity of ACE2 binding, the faster and more complete the mucosal diffusion in its transport from the upper airway to the region of the ACE2 target on the epithelium. This diffusional process is essential for the presentation of this virus to the furin catalysed highly efficient entry and infection process in the upper respiratory tract epithelial cells. A failure of SARS-CoV to follow this path is associated with lower respiratory tract infection and decreased infectivity. Thus, our analysis supports the view that through tropism SARS-CoV-2 has evolved a highly efficient membrane entry process that can act in concert with a high binding affinity of this virus and its variants for its ACE2 which in turn promotes enhanced movement of the virus from airway to epithelium. In this way ongoing mutations yielding higher affinities of SARS-CoV-2 for the ACE2 target becomes the basis for higher upper respiratory tract infectivity and greater viral spread. It is concluded that SARS-CoV-2 is constrained in the extent of its activities by the fundamental laws of physics and thermodynamics. Laws that describe diffusion and molecular binding. Moreover it can be speculated that the very earliest contact of this virus with the human mucosa defines the pathogenesis of this infection.

Systems analysis shows that thermodynamic physiological and pharmacological fundamentals drive COVID-19 and response to treatment.

Why a systems analysis view of this pandemic? The current pandemic has inflicted almost unimaginable grief, sorrow, loss, and terror at a global scale. One of the great ironies with the COVID-19 pandemic, particularly early on, is counter intuitive. The speed at which specialized basic and clinical sciences described the details of the damage to humans in COVID-19 disease has been impressive. Equally, the development of vaccines in an amazingly short time interval has been extraordinary. However, what has been less well understood has been the fundamental elements that underpin the progression of COVID-19 in an individual and in populations. We have used systems analysis approaches with human physiology and pharmacology to explore the fundamental underpinnings of COVID-19 disease. Pharmacology powerfully captures the thermodynamic characteristics of molecular binding with an exogenous entity such as a virus and its consequences on the living processes well described by human physiology. Thus, we have documented the passage of SARS-CoV-2 from infection of a single cell to species jump, to tropism, variant emergence and widespread population infection. During the course of this review, the recurrent observation was the efficiency and simplicity of one critical function of this virus. The lethality of SARS-CoV-2 is due primarily to its ability to possess and use a variable surface for binding to a specific human target with high affinity. This binding liberates Gibbs free energy (GFE) such that it satisfies the criteria for thermodynamic spontaneity. Its binding is the prelude to human host cellular entry and replication by the appropriation of host cell constituent molecules that have been produced with a prior energy investment by the host cell. It is also a binding that permits viral tropism to lead to high levels of distribution across populations with newly formed virions. This thermodynamic spontaneity is repeated endlessly as infection of a single host cell spreads to bystander cells, to tissues, to humans in close proximity and then to global populations. The principal antagonism of this process comes from SARS-CoV-2 itself, with its relentless changing of its viral surface configuration, associated with the inevitable emergence of variants better configured to resist immune sequestration and importantly with a greater affinity for the host target and higher infectivity. The great value of this physiological and pharmacological perspective is that it reveals the fundamental thermodynamic underpinnings of SARS-CoV-2 infection.

Human variation in response to food and nutrients.

The application of science to human nutrition over the centuries has served societies well. One example is the identification of key nutrients to overcome nutritional deficiencies, which has enhanced life expectancy. Enhanced life expectancy, however, is associated with an increased prevalence of chronic disorders related to food and nutrition. Findings of studies indicating that individual responses to nutrients differ substantially between individuals make it necessary to re-examine the relationship between nutrition and human health. The emergence of new genomic-based technologies illustrates the complexity and scale of the interactions between nutrition and genetic factors. Epigenetic modifications resulting from interactions of the genetic profile, aging, and lifestyle can influence the time course of chronic disorders and contribute to human variability in response to nutritional interventions. Developing a better understanding of human variability as it applies to human nutrition will involve embracing the approaches and principles of complex science.

Dietary butyrylated high-amylose starch reduces azoxymethane-induced colonic O(6)-methylguanine adducts in rats as measured by immunohistochemistry and high-pressure liquid chromatography.

O(6)-methyl guanine (O(6)MeG) adducts are major toxic, promutagenic, and procarcinogenic adducts involved in colorectal carcinogenesis. Resistant starch and its colonic metabolite butyrate are known to protect against oncogenesis in the colon. In this study, we hypothesized that a dietary intervention that specifically delivers butyrate to the large bowel (notably butyrylated high-amylose maize starch [HAMSB]) would reduce colonic levels of O(6)MeG in rats shortly after exposure to the deoxyribonucleic acid (DNA) alkylating agent azoxymethane (AOM) when compared with a low-amylose maize starch (LAMS). A further objective was to validate an immunohistochemistry (IHC) method for quantifying O(6)MeG against a high-performance liquid chromatography method using fluorescence and diode array detection. Rats were fed either LAMS or HAMSB diets for 4 weeks followed by a single injection of AOM or saline and killed 6 hours later. After AOM exposure, both IHC and high-performance liquid chromatography method using fluorescence and diode array detection measured a substantially increased quantity of DNA adducts in the colon (P<.001). Both techniques demonstrated equally that consumption of HAMSB provided a protective effect by reducing colonic adduct load compared with the LAMS diet (P<.05). In addition, IHC allowed visualization of the O(6)MeG distribution, where adduct load was reduced in the lower third of the crypt compartment in HAMSB-fed rats (P=.036). The apoptotic response to AOM was higher in the HAMSB-fed rats (P=.002). In conclusion, the reduction in O(6)MeG levels and enhancement of the apoptotic response to DNA damage in the colonic epithelium through consumption of HAMSB provide mechanistic insights into how HAMSB protects against colorectal tumorigenesis.

Repair and removal of azoxymethane-induced O6-methylguanine in rat colon by O6-methylguanine DNA methyltransferase and apoptosis.

Azoxymethane (AOM) is an alkylating agent that generates mutagenic and carcinogenic O(6)-methylguanine (O(6)meG) adducts in DNA. O(6)meG has been detected in human colonic DNA; hence, understanding the innate cellular events occurring in response to the formation of O(6)meG is important in developing preventive strategies for colorectal cancer. We explored the time-course, dose-response, and kinetics of O(6)meG formation and its removal by the DNA repair protein, O(6)-methylguanine DNA methyltransferase (MGMT), and apoptosis. In rats given AOM (10 mg/kg), the formation of O(6)meG occurs within 2 h of exposure, accompanied by rapid depletion of MGMT activity and followed by the induction of an acute apoptotic response that peaks at 6-8 h. MGMT repair and apoptosis are dependent on AOM dose and O(6)meG load. Apoptosis is initiated only when a high O(6)meG load is present and MGMT activity is fully depleted. AOM, 10 mg/kg, overwhelms MGMT repair for about 96 h and renewed MGMT activity is only observed once O(6)meG is no longer detectable. A threshold for apoptosis is observed at 6 h after 6 mg/kg AOM, when a high O(6)meG persists and MGMT activity is very low. These data suggest that apoptosis is probably triggered by O(6)meG, but only once the capacity of MGMT to repair O(6)meG is exhausted. In the colonic epithelium, apoptosis may be complementary to MGMT, in terms of minimising potentially mutagenic events and maintaining a healthy genome.

Research and standardization in Alzheimer's trials: reaching international consensus.

Alzheimer's disease (AD) is an epidemic facing the entire world. Increased knowledge gained during the past 25 years indicates that AD falls along a clinical and neuropathological spectrum represented as a continuum that extends from preclinical disease in which there are no symptoms, through early symptomatic phases, and finally to AD dementia. The Alzheimer's research community recognizes that imaging, body fluids, and cognitive biomarkers contribute to enhanced diagnostic confidence for AD. There has also been emerging consensus regarding the use of AD biomarkers in clinical trials. The use of biomarkers in clinical trials and practice is hampered by the lack of standardization. In response to the emerging need for standardization, an international meeting of AD researchers was held in Melbourne, Australia, in March 2012 to bring together key researchers, clinicians, industry, and regulatory stakeholders with the aim of generating consensus on standardization and validation of cognitive, imaging, and fluid biomarkers, as well as lifestyle parameters used in research centers worldwide.

Identification of potential pathways involved in induction of apoptosis by butyrate and 4-benzoylbutyrate in HT29 colorectal cancer cells.

Butyrate and its analogues have long been investigated as potential chemotherapeutic agents. Our previous structure-activity relationship studies of butyrate analogues revealed that 4-benzoylbutyrate had comparable in vitro effects to butyrate when used to treat HT29 and HCT116 colorectal cancer cell lines. The aim of this study was to identify potential mechanisms associated with the antitumorigenic effects of 4-benzoylbutyrate. In this study, butyrate, 3-hydroxybutyrate and 4-benzoylbutyrate were also investigated for their effects on histone deacetylase (HDAC) activity and histone H4 acetylation in HT29 and HCT116 cells. The biological effects of these analogues on HT29 cells were further investigated using quantitative proteomics to determine the proteins potentially involved in their apoptotic and antiproliferative effects. Because 3-hydroxybutyrate had minimal to no effect on apoptosis, proliferation or HDAC activity, this analogue was used to identify differentially expressed proteins that were potentially specific to the apoptotic effects of butyrate and/or 4-benzoylbutyrate. Butyrate treatment inhibited HDAC activity and induced H4 acetylation. 4-Benzoylbutyrate inhibited HDAC activity but failed to enhance H4 acetylation. Proteomic analysis revealed 20 proteins whose levels were similarly altered by both butyrate and 4-benzoylbutyrate. Proteins that showed common patterns of differential regulation in the presence of either butyrate or 4-benzoylbutyrate included c-Myc transcriptional targets, proteins involved in ER homeostasis, signal transduction pathways and cell energy metabolism. Although an additional 23 proteins were altered by 4-benzoylbutyrate uniquely, further work is required to understand the mechanisms involved in its apoptotic effects.

Modulation of in vitro activity of zymogenic and mature recombinant human ß-secretase by dietary plants.

The in vitro activity of human recombinant ß-secretase (BACE1) was studied using a fluorogenic substrate based on the cleavage site for the enzyme in the Swedish mutation of amyloid precursor protein. The enzyme was inhibited by a control peptide inhibitor with good repeatability. The enzyme preparation comprised a mixture of pro-enzyme or zymogen and mature enzyme whereby the pro-enzyme sequence forms a 'flap' that can obstruct the binding site. 'Open flap' forms of the zymogen and mature enzyme are active, but the 'closed flap' form of the zymogen is inactive. This mixture of enzyme populations permitted apparent stimulation of enzyme activity under particular conditions, presumably due to facilitating flap-opening of the zymogen. As reported for heparin, enzyme activation was stimulated in the presence of low concentrations of Tween 20 and dimethylsulfoxide before becoming inhibited at higher concentrations. Dietary plant extracts either consistently inhibited (e.g. clove, tea, cinammon) or consistently stimulated (e.g. mushroom, parsley, asparagus) BACE1. Common structural features identified by Fourier transform infrared spectroscopy revealed that BACE1 activity could be explained by differential interactions of either small molecule or polymeric species with mature versus zymogen forms of the enzyme, respectively. Further, enzyme activity could be reversed by mixtures of high and low mass species. These results may have implications for the regulation of ß-secretase activity in vivo by either endogenous or possibly dietary factors and for a potential role of BACE1 in stimulation of the production of amyloid beta peptide in sporadic Alzheimer's disease.

Rosemary and cancer prevention: preclinical perspectives.

Colorectal cancer is the second leading cause of cancer death in Australia. Nutrition, particularly intake of vegetables and certain plant components, has been reported to have a major role in cancer risk reduction. Recently, there has been a growing research interest in rosemary, a common household plant grown in many parts of the world. This study aims to review scientific evidence from all studies, published from 1996 to March 2010 that examined the protective effects of rosemary on colorectal cancer and other types of cancer. Literature evidence from animal and cell culture studies demonstrates the anticancer potential of rosemary extract, carnosol, carnosic acid, ursolic acid, and rosmarinic acid. No evidence for other rosemary constituents was found. The reported anticancer properties were found to arise through the molecular changes in the multiple-stage process of cancer development, which are dose related and not tissue or species specific. This is evidenced by the ability of rosemary to suppress the development of tumors in several organs including the colon, breast, liver, stomach, as well as melanoma and leukemia cells. The results suggested that the different molecular targets modulated by rosemary and its active constituents are useful indicators of success in clinical cancer chemo-prevention trials.

Effects of casoxin 4 on morphine inhibition of small animal intestinal contractility and gut transit in the mouse.

BACKGROUND AND AIMS: Chronic opioid analgesia has the debilitating side-effect of constipation in human patients. The major aims of this study were to: 1) characterize the opioid-specific antagonism of morphine-induced inhibition of electrically driven contraction of the small intestine of mice, rats, and guinea pigs; and 2) test if the oral delivery of small milk-derived opioid antagonist peptides could block morphine-induced inhibition of intestinal transit in mice. METHODS: Mouse, rat, and guinea pig intact ileal sections were electrically stimulated to contract and inhibited with morphine in vitro. Morphine inhibition was then blocked by opioid subtype antagonists in the mouse and guinea pig. Using a polymeric dye, Poly R-478, the opioid antagonists casoxin 4 and lactoferroxin A were tested orally for blocking activity of morphine inhibition of gut transit in vivo by single or double gavage techniques. RESULTS: The guinea pig tissue was more sensitive to morphine inhibition compared with the mouse or the rat (IC(50) [half maximal inhibitory concentration] values as nmol/L ± SEM were 34 ± 3, 230 ± 13, and 310 ± 14 respectively) (P < 0.01). The inhibitory influence of opioid agonists (IC(50)) in electrically driven ileal mouse preparations were DADLE ([D-Ala(2), D-Leu(5)]-enkephalin) ≥ met-enkephalin ≥ dynorphin A ≥ DAMGO ([D-Ala(2), N-Me-Phe(4), Glyol(5)]-enkephalin) > morphine > morphiceptin as nmol/L 13.9, 17.3, 19.5, 23.3, 230, and 403 respectively. The mouse demonstrated predominantly κ- and δ-opioid receptor activity with a smaller µ-opioid receptor component. Both mouse and guinea pig tissue were sensitive to casoxin 4 antagonism of morphine inhibition of contraction. In contrast to naloxone, relatively high oral doses of the µ-opioid receptor antagonists, casoxin 4 and lactoferroxin A, applied before and after morphine injection were unable to antagonize morphine inhibition of gut transit. CONCLUSIONS: Casoxin 4 reverses morphine-induced inhibition of contraction in mice and guinea pigs in vitro but fails to influence morphine inhibition of mouse small intestinal transit by the oral route.

Application of logic models in a large scientific research program.

It is the purpose of this article to discuss the development and application of a logic model in the context of a large scientific research program within the Commonwealth Scientific and Industrial Research Organisation (CSIRO). CSIRO is Australia's national science agency and is a publicly funded part of Australia's innovation system. It conducts mission-driven scientific research focussed on delivering results with relevance and impact for Australia, where impact is defined and measured in economic, environmental and social terms at the national level. The Australian Government has recently signalled an increasing emphasis on performance assessment and evaluation, which in the CSIRO context implies an increasing emphasis on ensuring and demonstrating the impact of its research programs. CSIRO continues to develop and improve its approaches to impact planning and evaluation, including conducting a trial of a program logic approach in the CSIRO Preventative Health National Research Flagship. During the trial, improvements were observed in clarity of the research goals and path to impact, as well as in alignment of science and support function activities with national challenge goals. Further benefits were observed in terms of communication of the goals and expected impact of CSIRO's research programs both within CSIRO and externally. The key lesson learned was that significant value was achieved through the process itself, as well as the outcome. Recommendations based on the CSIRO trial may be of interest to managers of scientific research considering developing similar logic models for their research projects. The CSIRO experience has shown that there are significant benefits to be gained, especially if the project participants have a major role in the process of developing the logic model.

Is the tissue persistence of O(6)-methyl-2'-deoxyguanosine an indicator of tumour formation in the gastrointestinal tract?

Azoxymethane (AOM) is a methylating agent capable of inducing mutations in DNA by forming adducts with DNA bases. It has been used to understand the mechanisms involved in colon carcinogenesis. Of the adducts formed in response to AOM, O(6)-methyl-2'-deoxy-guanosine (O(6)-mdGua) is the most mutagenic. Based on studies in rodents of the abundance and persistence of DNA adducts in various tissues after treatment with alkylating agents, previous results suggest, as a generalization, that the longer O(6)-mdGua adducts remain unrepaired in the cells of a tissue, the greater the risk for tumorigenesis. To test this hypothesis, we have built on these studies, expanding the number of tissues in which O(6)-mdGua abundance and persistence were examined and correlating these data with tumour distribution and abundance in rats maintained for 26 weeks after the treatment with AOM. Our study revealed firstly the existence of groups of tissues that developed relatively large amounts (proximal and distal colon, proximal small intestine (SI), liver and kidney) and relatively low levels (stomach, distal SI, bladder, spleen, blood and lung) of O(6)-mdGua after AOM exposure. Secondly, while all tissues showed an increase in adduct levels at 6h after mutagen treatment and most showed a significant drop in adduct levels between 6h and 48h (stomach, proximal and distal SI, liver, spleen, blood and lung), one group of tissues displayed O(6)-mdGua levels that did not decrease at 48h (proximal and distal colon, kidney and bladder). Predictably, the colon displayed tumours 26 weeks after treatment. Interestingly, however, the proximal SI also displayed significant tumour formation at that time. Our findings demonstrate (1) a direct association between exposure to O(6)-mdGua and tumours of the distal colon and (2) a dissociation of the relationship between adduct clearance and tumorigenesis in the SI. This diversity of response in the gastrointestinal tract warrants further analysis.

Structure-activity relationship of butyrate analogues on apoptosis, proliferation and histone deacetylase activity in HCT-116 human colorectal cancer cells.

1. Butyrate, a bacteria fermentative product in the colonic lumen, has been shown to produce a wide variety of biological effects in human cancer cells in vitro. However, there are pharmacological drawbacks associated with the use of butyrate therapy and there are limited published data on the structure-activity relationship of butyrate analogues in colorectal cancer cells. Previously, we determined structure-activity relationship using HT-29 human colorectal cancer cells. However, it was viewed as important to explore similar relationships in another colorectal cancer cell line. 2. Therefore, in the present study, the in vitro structure-activity relationship of butyrate analogues was examined by investigating their effects on apoptosis, cell proliferation, histone deacetylase (HDAC) activity and lactate dehydrogenase (LDH) leakage as a measure of cell toxicity in HCT-116 human colorectal cancer cells. 3. Of the 32 analogues tested, only 4-benzoylbutyrate, 3-benzo-ylpropionate, 4-(4-nitrophenyl)butyrate and 3-(4-fluorobenzoyl)propionate exhibited comparable biological effects to butyrate. The common structural properties of the compounds of interest were to lack amino or hydroxyl substitutions at the 2-, 3- and/or 4-position of the aliphatic moiety of butyrate. 4. The present study reveals a dissociation between the induction of apoptosis, inhibition of cell proliferation, HDAC activity and LDH leakage. The results indicate differential responses of butyrate analogues in HT-29 and HCT-116 colorectal cancer cells.

Efficacy of butyrate analogues in HT-29 cancer cells.

1. Butyrate is a well known product of starch fermentation by colonic bacteria and is of interest owing to its ability to induce in vitro apoptosis and cell differentiation, as well as to inhibit cell growth in colorectal and other cancer cells. Synthetic analogues of butyrate may also possess cellular activities in a variety of cultured cells. The aim of the present study was to evaluate the effects of butyrate analogues on apoptosis, proliferation and histone deacetylase (HDAC) activity in HT-29 colorectal cancer cells. In addition, the effects of these analogues on lactate dehydrogenase leakage, as a measure of non-specific cytotoxicity, were evaluated in HT-29 cells. 2. Of the 26 analogues examined, four (propionate, 4-benzoylbutyrate, 4-(4-aminophenyl)butyrate and benzyloxyacetate) exhibited comparable effects to butyrate. Interestingly, no activity was noted for compounds carrying amino, hydroxyl or methyl substitutions at the 2-, 3- or 4-position of the aliphatic moiety of butyrate. 3. In conclusion, chemical changes to the structure of butyrate can significantly modify the biological activity assayed in HT-29 colorectal cancer cells in vitro.

Cardiovascular biology of interleukin-6.

Interleukin-6 (IL-6) is a multifunctional pro-inflammatory cytokine that is tightly regulated and expressed at low levels in healthy individuals. Increased IL-6 expression has been associated with a variety of diseases, including inflammatory conditions such as atherosclerosis and cardiovascular disease (obesity, myocardial infarction and type II diabetes). Cytokines including IL-6 and tumour necrosis factor alpha as well as acute phase proteins such as C-reactive protein (CRP) and fibrinogen are key biochemical risk factors for the development of these disease conditions. IL-6 is the key cytokine responsible for the stimulus of synthesis and secretion of CRP. IL-6 activates cell surface signalling via the assembly of IL-6, the IL-6 receptor (IL-6R) and the signalling receptor gp130. Assembly of the (hexameric) signalling complex of IL-6, IL-6R and gp130 occurs in a sequential manner and therefore this signalling complex lends itself to several potential sites for drug targeting. This review discusses some of the mechanisms of IL-6 signalling on various aspects of cardiovascular biology as well as some recent developments in drug targeting of this complex.

Site specific delivery of microencapsulated fish oil to the gastrointestinal tract of the rat.

The aim of this study was to design food grade matrices to deliver microencapsulated fish oil to the large bowel of the rat where the potential exists to retard inflammation and cancer development. Digestion in simulated gastric fluid and intestinal fluid demonstrated that only 4-6% of oil was released from the following dried emulsion formulations: 50% fish oil encapsulated in heated casein-glucose-dried glucose syrup (1:1:1) (Cas-Glu-DGS-50); 25% fish oil in casein-modified resistant starch (Hylon VII) (1:1) (Cas-Hylon-25); or 25% fish oil in Cas-Glu-Hylon (1:1:1) (Cas-Glu-Hylon-25). A short-term gavage study (0-12 h) with fish oil and Cas-Glu-DGS-50 demonstrated the appearance of fish oil long chain (LC) n-3 polyunsaturated fatty acids (PUFA) into the plasma indicating specific small intestinal absorption with little LC n-3 PUFA reaching the large bowel. In a 2-week-long term, daily gavage study, the bioavailability of fish oil and fish oil in Cas-Glu-DGS-50 or Cas-Hylon-25 demonstrated that fish oil and Cas-Glu-DGS-50 LC n-3 PUFA were incorporated into the tissue of the small intestine and colon, whereas Cas-Hylon-25 was resistant to degradation in the small intestine. The use of modified Hylon VII for targeted colonic delivery was confirmed in the final short-term gavage study (0-14 h) using Cas-Glu-Hylon-25 with [(14)C]-trilinolenin as a marker incorporated into the microcapsules, where up to 60% of the labeled oil reached the large bowel. Depending on the microencapsulating matrix employed, fish oil can be delivered selectively to the small intestine or to a high degree to the large bowel.

Does garlic reduce risk of colorectal cancer? A systematic review.

Colorectal cancer (CRC) is the 3rd leading cause of cancer death in the United States and the 2nd leading cause of cancer death in Australia. Environmental factors play important roles in the multiple-stage process of CRC and nutritional intervention has been identified as playing a major role in its prevention. The aim of this study was to review systematically the scientific evidence from all studies conducted over the last decade that examined effects of garlic on CRC. Levels of evidence were ranked from level I to level V according to study designs and the quality of each study was assessed against a set of quality criteria based on those used by the National Health and Medical Research Council in Australia. One randomized controlled trial (RCT, level II) reported a statistically significant 29% reduction in both size and number of colon adenomas in CRC patients taking aged garlic extract. Five of 8 case control/cohort studies (level III) suggested a protective effect of high intake of raw/cooked garlic and 2 of 8 of these studies suggested a protective effect for distal colon. A published meta-analysis (level III) of 7 of these studies confirmed this inverse association, with a 30% reduction in relative risk. Eleven animal studies (level V) demonstrated a significant anticarcinogenic effect of garlic and/or its active constituents. On balance, there is consistent scientific evidence derived from RCT of animal studies reporting protective effects of garlic on CRC despite great heterogeneity of measures of intakes among human epidemiological studies.

Age- and hypertension-induced changes in abnormal contractions in rat aorta.

The current investigation explored the potential age-dependant modulation of abnormal spontaneous constrictions (thromboxane-like) in the spontaneously hypertensive rat (SHR) aorta, observed only after the inhibition of endogenous production of nitric oxide (NO). Aortic rings from SHR and Wistar-Kyoto (WKY) control rats of varying ages (4, 8, 12, and 18 months) were mounted in organ baths, and changes in tension were monitored. Inhibition of NO with Nomega-nitro-L-arginine (NOLA) unmasked a slow contraction, which appeared to be age dependent (p < 0.05). This contraction was found in SHRs of all age groups and in older WKY rats. Denuding the endothelium in young SHRs did not influence the constriction, confirming a nonendothelial cell origin, while in the older groups this led to a 30-40% reduction in contraction. Comparable attenuation of the constrictor response was observed after incubation of endothelium intact rings with superoxide dismutase (100 U/ml) or 3-amino-1,2,4-triazole. Of the residual activity that was unaffected by free radical scavengers or de-endothelialization, 60-70% was sensitive to cyclooxygenase inhibition by indomethacin and/or ibuprofen. The thromboxane (TxA ) receptor antagonist SQ29548 induced a complete reversal of the abnormal constriction. In contrast, thromboxane synthetase inhibition had no effect, ruling out any involvement of TxA in mediating this abnormality. Collectively, these observations support the view that as compared with the normotensive setting, contraction induced by NO inhibition in the SHR develops prematurely and deteriorates more rapidly during the aging process. In aged rats, prostaglandin endoperoxide intermediates PGG /H and endothelium-derived free radicals rather than TxA per se appear to contribute to the NOLA-dependent TxA -like vasoconstriction.