Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancer

Transition from traditional high-fiber to Western diets in urbanizing communities of Sub-Saharan Africa is associated with increased risk of non-communicable diseases (NCD), exemplified by colorectal cancer (CRC) risk. To investigate how urbanization gives rise to microbial patterns that may be amenable by dietary intervention, we analyzed diet intake, fecal 16 S bacteriome, virome, and metabolome in a cross-sectional study in healthy rural and urban Xhosa people (South Africa). Urban Xhosa individuals had higher intakes of energy (urban: 3,578 ± 455; rural: 2,185 ± 179 kcal/d), fat and animal protein. This was associated with lower fecal bacteriome diversity and a shift from genera favoring degradation of complex carbohydrates (e.g., Prevotella) to taxa previously shown to be associated with bile acid metabolism and CRC. Urban Xhosa individuals had higher fecal levels of deoxycholic acid, shown to be associated with higher CRC risk, but similar short-chain fatty acid concentrations compared with rural individuals. Fecal virome composition was associated with distinct gut bacterial communities across urbanization, characterized by different dominant host bacteria (urban: Bacteriodota; rural: unassigned taxa) and variable correlation with fecal metabolites and dietary nutrients. Food and skin microbiota samples showed compositional differences along the urbanization gradient. Rural-urban dietary transition in South Africa is linked to major changes in the gut microbiome and metabolome. Further studies are needed to prove cause and identify whether restoration of specific components of the traditional diet will arrest the accelerating rise in NCDs in Sub-Saharan Africa.

Prolonged exposure to extracellular lumican restrains pancreatic adenocarcinoma growth

We previously demonstrated that pancreatic stellate cells within pancreatic ductal adenocarcinoma (PDAC) stroma secrete lumican and its presence is associated with prolonged survival of patients with localized PDAC. Here, we observed that extracellular lumican decreases PDAC tumour cell growth in xenograft and syngeneic orthotopic animal models, and induces growth inhibition of low-passage human PDAC cells in a species-specific manner. PDAC cells grown in variant culture conditions and exposed to extracellular lumican display typical characterizations of cancer cell in a quiescent state, such as growth inhibition, apoptosis, G0/G1 arrest and chemoresistance. Importantly, extracellular lumican is associated with diminished ERK1/2 phosphorylation and increased p38 phosphorylation within PDAC cells. We further demonstrated that extracellular lumican physically binds with EGFR to trigger EGFR internalization and downregulation of EGFR and its downstream signal molecule ERK. Lumican enhances casitas B-lineage lymphoma expression, which stabilized the TGFβ Type II receptor sensitizing PDAC cells to TGFβ-mediated activation of p38 and SMAD signals. These provide a mechanism for the shift in signalling and phenotypic changes we observed after prolonged exposure to lumican. Together, our findings demonstrate that stromal lumican restrains PDAC cell growth through mediating cell entry into a quiescent state.

Direct and indirect modulation of rat cardiac sarcoplasmic reticulum function by n-3 polyunsaturated fatty acids

Measurements were made of trans-sarcolemmal Ca(2+) fluxes and intracellular [Ca(2+)](i) in rat ventricular myocytes loaded with Indo-1 to determine how the n-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) suppresses spontaneous waves of Ca(2+) release. We report that in 10 microM EPA, the Ca(2+) efflux generated by individual waves increased by 11.3 +/- 4.9 % over control levels. However, wave-generated efflux per unit time fell overall by 19 +/- 5.3 %. On removal of EPA, wave frequency increased transiently such that Ca(2+) efflux was greater than normal and the cell lost 28.0 +/- 10.6 micromol l(-1) Ca(2+). This probably represents the loss of extra Ca(2+) accumulated by the sarcoplasmic reticulum (SR), while Ca(2+) release was inhibited. These results are evidence of inhibition of the SR Ca(2+)-release mechanism and reduced availability of Ca(2+) to the SR. From the relationship between average intracellular Ca(2+) and the frequency of spontaneous waves, we have calculated the relative contributions of these different mechanisms to the lower frequency of waves. In EPA, the frequency of spontaneous waves fell by 37.5 +/- 8.1 %, the majority of this (29.2 +/- 8.8 %) is due to inhibition of the Ca(2+)-release mechanism. In EPA, the rate of fall of Ca(2+) in the caffeine response (an indicator of surface membrane Ca(2+) efflux pathway activity) was not altered. We conclude, therefore, that the lower resting level of Ca(2+) observed in EPA is due to a lower influx of Ca(2+) across the surface membrane rather than increased activation of efflux pathways. How these effects might contribute to the anti-arrhythmic actions of EPA is discussed.

Inhibition of sarcoplasmic reticulum function by polyunsaturated fatty acids in intact, isolated myocytes from rat ventricular muscle

1. We have studied the effects of two polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on spontaneous and electrically stimulated contractions in single, isolated ventricular myocytes from rat hearts. 2. The frequency of spontaneous waves of calcium release and contraction (induced by elevation of the bathing calcium concentration) is reduced in the presence of EPA. At the same time the resting level of intracellular calcium falls, the resting cell length increases and the amplitude of shortening decreases. All these effects are reversed on removal of EPA. 3. Imaging of the waves of calcium release shows that the amplitude and the rate of propagation of the wave is increased in EPA. Consistent with the increased amplitude, integration of the caffeine-induced Na+-Ca2+ exchange current (a measure of the sarcoplasmic reticulum (SR) calcium content) is increased by both EPA and DHA. 4. EPA has a maintained negative inotropic effect on voltage clamped myocytes. This seems to be entirely due to inhibition of the L-type calcium current. Smaller depolarising pulses in control conditions that elicit the same calcium current as in EPA also activate the same level of contraction. This is in spite of the increased SR calcium content in EPA. 5. It is concluded that PUFAs have two effects on the SR; they reduce the availability of calcium for uptake and they inhibit the release mechanism. Both of these effects should lower the frequency of spontaneous waves of calcium release. As spontaneous release of calcium can initiate arrhythmias, some of the anti-arrhythmic action of PUFAs must be exerted at the level of the SR.

Interferon alpha treatment of chronic hepatitis C in HIV-infected patients receiving zidovudine: efficacy, tolerance and response related factors

BACKGROUND/AIMS

In our area most of the human immunodeficiency virus (HIV) infected patients are intravenous drug users; HIV and hepatitis C virus infections often coexist in these patients. Due to the repercussions of both infections, we designed a trial to evaluate the efficacy, response-related factors and tolerance during an eight-month regime of recombinant interferon alpha-2b on hepatitis C virus infection.

METHODOLOGY

We included 79 patients in an open, prospective and multicentric trial with zidovudine and interferon alpha-2b. Response to interferon treatment was evaluated by biochemical and histopathological criteria.

RESULTS

A complete response (alanine aminotransferase normalization) was obtained in 57.4% of patients. The significant response-related factors were: degree of histopathological activity, CD4+ cell number and initial leukocyte number.

CONCLUSIONS

Recombinant interferon therapy seems to be effective for chronic hepatitis C in HIV infected patients; the best response was in those with active chronic hepatitis and CD4+ cell counts > or = 200/mm3. General tolerance was variable, although side effects were not different from those seen in non-HIV patients. The most common side effect was flu-like syndrome (constitutional manifestations), with no interference on treatment continuity; however, hematological toxicity prevents the indiscriminate use of interferon.

Computed tomography, sonographic, and radiographic findings in adrenal myelolipoma

We report on a patient with a large adrenal myelolipoma which was suspected pre-operatively on the basis of sonographic, computed tomography (CT), and radiographic findings.

Diagnosis of pyogenic hepatic abscesses by percutaneous transhepatic cholangiography

Four of 83 patients undergoing percutaneous transhepatic cholangiography were demonstrated to have hepatic abscesses communicating with the biliary tract. The abscesses resulted from obstruction of the common bile duct. The etiologies of the obstructions were chronic pancreatitis, recurrent cholangiocarcinoma. Radiographic demonstration of suppurative cholangitis is associated with a very poor prognosis.

Clinical applications of nonoperative T-tube replacement

T tubes were successfully reintroduced through previously created drainage tracts in 17 consecutive attempts. The new tubes can re-establish bile flow in a variety of circumstances in avoiding reoperation.

Removal of a distal common bile duct stone through percutaneous transhepatic catheterization

A residual distal common bile duct stone was successfully advanced into the duodenum after percutaneous transhepatic catheterization of the biliary tract. Nonsurgical retrieval of retained biliary duct stones through surgically created T-tube tracts has been shown to be a practical procedure with high reported success rates. Reoperation has been necessary in cases where no drainage tube was introduced at surgery or when stones have formed after the fistula closed. Transhepatic catheterization techniques may provide a way to manipulate residual biliary tract stones when no other access is available.