The in-vivo oxyhaemoglobin dissociation curve at sea level and high altitude

Animals native to hypoxic environments have adapted by increasing their haemoglobin oxygen affinity, but in-vitro studies of the oxyhaemoglobin dissociation curve (ODC) in humans show no changes in affinity under physiological conditions at altitudes up to 4000 m. We conducted the first in-vivo measurement of the ODC; inducing progressive isocapnic hypoxia in lowlanders at sea level, acutely acclimatized lowlanders at 3600 m, and native Andeans at that altitude. ODC curves were determined by administering isocapnic steps of increasing hypoxia, and measuring blood oxygen partial pressure and saturation. The ODC data were fitted using the Hill equation and extrapolated to predict the oxygen partial pressure at which haemoglobin was 50% saturated (P₅₀). In contrast to findings from in-vitro studies, we found a pH-related reduction in P₅₀ in subjects at altitude, compared to sea-level subjects. We conclude that a pH-mediated increase in haemoglobin oxygen affinity in-vivo may be part of the acclimatization process in humans at altitude.     

Laparoscopic colectomy without mechanical bowel preparation

Background Mechanical bowel preparation prior to colorectal surgery may reduce infectious complications, facilitate tumor localization, and allow intraoperative colonoscopy, if required. However, recent data suggest that mechanical bowel preparation may not facilitate a reduction in infectious complications. During laparoscopic colectomy, manual palpation is blunt, thereby potentially compromising tumor localization. The aim of this study was to assess the utility of mechanical bowel preparation in laparoscopic colectomy.Materials and methods A retrospective medical record review of all patients who underwent laparoscopic colectomy was performed. Patients were divided into two groups: those who had preoperative mechanical bowel preparation (Group A) or those who did not (Group B). All relevant perioperative data were reviewed and compared.Results Two hundred patients underwent laparoscopic colectomy; 68 (34%) were in Group A and 132 (66%) were in Group B. Sixteen (8%) patients required intraoperative colonoscopy for localization and were evenly distributed between the two groups. The incidence of conversion to laparotomy was slightly higher in Group B (14 vs 9%) due to difficult localization in some cases; however, this difference did not reach statistical significance. Furthermore, there was no significant difference in the postoperative complication rate between the two groups. Specifically, an anastomotic leak and a wound infection were recorded in 4 and 12% of patients in Group A compared to 3 and 17% in Group B, respectively.Conclusions Laparoscopic colectomy may be safely performed without preoperative mechanical bowel preparation, although difficult localization may lead to a slightly higher conversion rate. Appropriate patient selection for laparoscopic colectomy without mechanical bowel preparation is essential. Furthermore, bowel preparation should be considered in cases of small and nonpalpable lesions.Dual first authorship—Zmora and Lebedyev, the first two authors, equally contributed to this study.Presented as a poster at the annual meeting of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), Denver, CO, March 31–April 3, 2004.     

Role of photoreactivation in case of corneal damage from ultraviolet radiation

Experimentally, the role of photoreactivation in appearance of ultraviolet lesions of corneal epithelium has been studied in white rats. The lesions were induced by ultraviolet radiation, 0.28 mcm wavelength, and intensive (20000 lx) light of a xenon lamp with light filters was used as a reactivating light. The damaging dose as a reactivating light. The damaging dose of ultraviolet radiation by photokeratitis criterion was 11 +/- 2.4 mJ.cm-2. Simultaneous illumination of the animal eye by the damaging ultraviolet light and reactivating radiation exceeded a damaging threshold to 18 +/- 4.0 mJ.cm-2. The results obtained have convincingly shown, that photoreactivation, as a phenomenon, manifested itself in the corneal epithelium and was detected by biomicroscopy of the eye with epithelium staining by a 1% fluorescein solution.     

Composite tissue allotransplantation.

Composite tissue allotransplantation (CTA) recently took its first steps in the clinical arena in 1998 with the successful hand transplant performed in Lyons, France. That single operation represented a culmination of many years of laboratory research in multiple fields involving integumentary/musculoskeletal transplantation. Here we review the prerequisite developments in the field of immunology, microsurgery, and pharmacotherapy that helped bring CTA to clinical reality. This new field still has many unanswered questions which are addressed below. Additionally, new evolving research in CTA is also discussed.     

1H and 13C nuclear magnetic resonance studies of plasma from patients with primary intracranial neoplasms

Plasma from patients with malignant and benign primary intracranial neoplasms and from healthy control subjects has been examined using proton (1H) and carbon-13 nuclear magnetic resonance (NMR) spectroscopy. Some features in the spectra of plasma from patients with malignant tumors differ significantly (p less than 0.01) from the corresponding features in the spectra of plasma from control subjects and from patients with benign tumors. The NMR spectral parameters vary consistently with the Kernohan grade of astrocytoma, which may suggest that they give a measure of tumor growth kinetics. The observed spectral differences are shown to be due to elevated levels of monounsaturated and polyunsaturated fatty acid residues in the plasma of cancer patients. It is proposed that these lipid residues arise from cell membranes shed from cells in growing tumors. The ability to follow tumor growth kinetics directly may be of considerable importance in elucidating the effects of primary intracranial neoplasm therapy.     

Effect of naringenin and its combination with cisplatin in cell death,proliferation and invasion of cervical cancer spheroids

The main treatment alternative for cervical cancer is cisplatin chemotherapy. However, the resistance of tumor cells to cisplatin, in addition to side effects, limits its use. The flavonoid naringenin has shown cytotoxic effects on tumor cells and may be considered as a coadjuvant in the treatment of cervical cancer. In the present study, the effect of naringenin on cell viability, cytotoxicity, proliferation, apoptosis and invasion was evaluated in HeLa spheroid cultures. Naringenin impaired the cell viability as indicated by low ATP levels and caused concentration- and time-dependent cytotoxicity via the loss of cell membrane integrity. Furthermore, it did not activate caspases 3, 7, 8, and 9, suggesting that the cytotoxic effect was by necrotic cell death instead of apoptosis. Additionally, proliferation in the G0/G1 phase of the cell cycle was inhibited. Cell invasion also decreased as time progressed. Later, we determined if naringenin could improve the anti-tumor effect of cisplatin. The combination of naringenin with low concentrations of cisplatin improved the effect of the drug by significantly decreasing cell viability, potentiating the induction of cytotoxicity and decreasing the invasive capacity of the spheroids. Since these effects are regulated by some key proteins, molecular docking results indicated the interaction of naringenin with RIP3 and MLKL, cyclin B and with matrix metalloproteases 2 and 9. The results showed the anti-tumor effect of naringenin on the HeLa spheroids and improved effect of the cisplatin at low concentrations in combination with naringenin, placing flavonoids as a potential adjuvant in the therapy against cervical cancer.

The combination of naringenin–cis-platin prevents the invasion of cancer, at a lower concentration of cis-platin.