Denaturing interaction between sickle hemoglobin and phosphatidylserine liposomes

It is hypothesized that abnormal interaction between sickle hemoglobin (HbS) and erythrocyte membrane lipid might promote deposition of denatured hemoglobin (hemichrome) on the membrane. We compared the interaction of HbS and normal HbA with large unilamellar phosphatidylserine (PS) liposomes under low salt/pH conditions. Admixture of oxyHb and dioleoyl-PS resulted in loss of absorbance at 412 nm, the apparent first order rate constant for which was .25 +/- 0.02 hour-1 for HbA and .85 +/- 0.18 hour-1 for HbS. This was ascribable largely to formation of metHb and hemichromes and was accompanied by some actual transfer of heme from hemoglobin to lipid phase. By comparison, admixture of oxyHb with liposomes made from bovine brain PS having unsaturated acyl chains promoted even faster absorbance loss if the starting liposomal material contained detectable peroxidation by-product. In such cases, actual heme destruction developed with accompanying liberation of free iron and promotion of lipidperoxidation. Fluorescence quenching experiments indicate that hemoglobin/lipid interaction is characterized by very rapid initial electrostatic interaction, followed by development of irreversible changes. Similar changes still occur under conditions of physiologic salt/pH, but they develop much more slowly. The 3.4-fold faster oxidation of HbS versus HbA on lipid observed here represents an additional augmentation of the disparity in oxidation rates for hemoglobins in solution (1.7-fold faster for HbS than for HbA) observed previously. The accelerated promotion of Hb denaturation resulting from lipid contact may help explain deposits of hemichrome on sickle red blood cell membranes, particularly because these cells are in double jeopardy by virtue of having both the mutant HbS and abnormal amounts of peroxidized membrane lipid.     

Long-term bone marrow culture in persons with Fanconi anemia and bone marrow failure

Fanconi anemia is an autosomal recessive disease characterized by a high risk of developing bone marrow (BM) failure and acute myelogenous leukemia. We studied growth of hematopoietic progenitor cells in long- term BM culture (LTBMC) in 8 persons with Fanconi anemia and BM failure. Although LTBMC were initiated with very few BM cells, an adherent layer formed in cultures from 7 persons. In these cultures, the number of nonadherent cells increased for 10 to 15 days. Cell growth continued until cultures were terminated at day 35 to 40. During the first 2 weeks of culture, most nonadherent cells were differentiated myeloid cells. By days 35 to 40, the adherent layer contained cells able to initiate secondary LTBMCs. These data indicate that hematopoietic precursors cells able to proliferate and differentiate in vitro are present in the BM of persons with Fanconi anemia and BM failure. They suggest that mechanisms other than absent precursor cells are responsible for BM failure in Fanconi anemia.     

T-cell death by apoptosis in vertically human immunodeficiency virus- infected children coincides with expansion of CD8+/interleukin-2 receptor-/HLA-DR+ T cells: sign of a possible role for herpes viruses as cofactors?

One mechanism proposed to play a role in T-cell depletion in human immunodeficiency virus (HIV) infection is apoptosis (activation-induced cell death). We assessed whether apoptosis is related to activation of T cells in vivo and its possible triggers. DNA was extracted from peripheral blood mononuclear cells (PBMC) taken from 16 vertically HIV- infected children and 9 HIV-negative children born to HIV-positive mothers (controls) and tested by agarose gel electrophoresis for the presence of DNA fragments specific for apoptosis. Signs of apoptosis were found on in vitro culture of PBMC from 12 of 16 HIV-infected children, but not in PBMC from the nine controls. Eleven of the 12 HIV- infected children with apoptosis showed an elevated (> 15%) proportion of CD3+/HLA-DR+ cells. This was due to an increased proportion of CD8+/HLA-DR+ cells, as shown in 7 of 7 further tested patients. In none of the probands an increased (> 5%) proportion of IL-2 receptor expressing CD3+ cells was found. T cells undergoing apoptosis were preferentially of the CD8+ phenotype. Expansion of circulating CD8+/interleukin-2 receptor (IL-2R)-/HLA-DR+ T cells is known to occur during active infection with herpes viruses. To investigate the possible role of herpes viral coinfections for apoptosis in HIV infection, we focused on Epstein-Barr virus (EBV) as an example for a herpes virus usually acquired during childhood. In 10 of 12 patients with apoptosis, we found increased levels of EBV genome in PBMC and/or tissues, indicating active EBV replication. By contrast, no increased burden of EBV was found in the four HIV-infected patients without apoptosis or in the controls. Our data indicate that in children the occurrence of apoptosis in HIV infection is closely related to activation of CD8+ T cells. Furthermore, primoinfection with or reactivation of herpes viruses, such as EBV, may substantially contribute to such T-cell activation and the ensuing apoptosis. Additional studies are warranted to evaluate the contribution of herpes virus-triggered apoptosis to the T-cell loss leading to the acquired immunodeficiency syndrome.     

Vasoactive intestinal peptide and pituitary adenylate cyclase- activating polypeptides (PACAP27) and PACAP38) protect CD4+CD8+ thymocytes from glucocorticoid-induced apoptosis

In the present study, the effects of vasoactive intestinal peptide (VIP) and the pituitary adenylate cyclase-activating polypeptides, PACAP27 and PACAP38, in a concentration range from 10(-13) to 10(-6) mol/L were studied in vitro on the spontaneous and dexamethasone (DEX)- induced apoptosis in rat thymocytes. The results show that VIP and both PACAPs inhibit significantly and in a similar way the DNA fragmentation characteristic of glucocorticoid-induced apoptosis and increase the cell survival of thymocytes, with a maximal effect observed at 10(-8) to 10(-9) mol/L. This study showed the ability of the VIP-receptor (VIP- R) antagonist [N-Ac-Tyr1,D-Phe2]-GRF(1-29) amide to partially reverse the inhibitory effect of VIP and both PACAPs on DEX-induced apoptosis, providing evidence for a specific VIP1-R-mediated response and supporting the involvement of a single receptor for the three neuropeptides. Phenotypic analysis showed that VIP, PACAP27, and PACAP38 protect predominantly CD4+CD8+ thymocytes from glucocorticoid- induced apoptosis. These findings suggest that these neuropeptides could be involved in intrathymic T-cell maturation.     

Exclusion of known gene for enamel development in two Brazilian families with amelogenesis imperfecta

Background

Functional rehabilitation of patients afflicted with severe mandibular and maxillary alveolar atrophy might be challenging especially in malformed patients.

Methods

Treatment planning using sinus lifting and implant placement before Le Fort I maxillary osteotomy in a patient with severe mandibular and posterior maxillary alveolar atrophy and skelettal class-III conditions due to cleft palate are described.

Results

A full functional and esthetic rehabilitation of the patient was achieved by a stepwise surgical approach performed through sinus lifting as the primary approach followed by implant placement and subsequent Le Fort I maxillary osteotomy to correct the maxillo-mandibular relation.

Conclusion

Stabilisation of the maxillary complex by a sinus lifting procedure in combination with computer aided implant placement as preorthodontic planning procedure before Le Fort I maxillary osteotomy seems to be suitable in order to allow ideal oral rehabilitation especially in malformed patients.     

Intraoperative cell salvage with autologous transfusion in liver transplantation

Liver transplant(LT) is the primary treatment for patients with end-stage liver disease. About 25000 LTs are performed annually in the world. The potential for intraoperative bleeding is quite variable. However, massive bleeding is common and requires blood transfusion. Allogeneic blood transfusion has an immunosuppressive effect and an impact on recipient survival, in addition to the risk of transmission of viral infections and transfusion errors, among others.Techniques to prevent excessive bleeding or to use autologous blood have been proposed to minimize the negative effects of allogeneic blood transfusion.Intraoperative reinfusion of autologous blood is possible through previous selfdonation or blood collected during the operation. However, LT does not normally allow autologous transfusion by prior self-donation. Hence, using autologous blood collected intraoperatively is the most feasible option. The use of intraoperative blood salvage autotransfusion(IBSA) minimizes the perioperative use of allogeneic blood, preventing negative transfusion effects without negatively impacting other clinical outcomes. The use of IBSA in patients with cancer is still a matter of debate due to the theoretical risk of reinfusion of tumor cells. However, studies have demonstrated the safety of IBSA in several surgical procedures, including LT for hepatocellular carcinoma. Considering the literature available to date, we can state that IBSA should be routinely used in LT, both in patients with cancer and in patients with benign diseases.     

Are vitamin B12 and folate deficiency clinically important after roux-en-Y gastric bypass?

Although iron, vltamm B₁₂, and folate deficiency have been well documented after gastric bypass operations performed for morbid obesity, there is surprisingly little information on either the natural course or the treatment of these deficiencies in Roux-en-Y gastric bypass (RYGB) patients Durmg a l0-year period, a complete blood count and serum levels of iron, total iron-binding capacity, vltamin B₁₂, and folate were obtained in 348 patients preoperatively and postoperatively at 6-month intervals for the first 2 years, then annually thereafter The principal objectives of this study were to determine how readily patients who developed metabolic deficiencies after Roux-en-Y gastric bypass responded to postoperative supplements of the deficient micronutrient and to learn whether the risk of developmg these deficiencies decreases over time Hemoglobin and hematocrit levels were slgnificantly decreased at all postoperative intervals in comparison to preoperative values Moreover, at each successive interval through 5 years, hemoglobin and hematocrit were decreased signifiantly compared to the preceding interval Folate levels were significantly increased compared to preoperative levels at all time intervals Iron and vltamin B₁₂ levels were lower than preoperative measurements and remained relatively stable postoperatively Half of the low hemoglobin levels were not associated with iron deficiency Taking multivltamin supplements resulted in a lower incidence of folate deficiency but did not prevent iron or vitamin B₁₂ deficiency Oral supplementation of iron and vitamin B₁₂ corrected defiaencies in 43% and 81% of cases, respectively Folate deficiency was almost always corrected with multivitamins alone No patient had symptoms that could be attributed to either vitamin B₁₂ or folate deficiency Conversely, many patients had symptoms of iron deficiency and anenua Lack of symptoms of vitamin B₁₂ and folate deficiency suggests that these deficiencies are not clinically important after RYGB Conversely, iron deficiency and anemia are potentially serious problems after RYGB, particularly in younger women Hence we recommend prophylactic oral iron supplements to premenopausal women who undergo RYGB     

Comparison of Phaconit Rollable IOL with Acrylic Foldable IOL

Background

Phaconit or ultra micro incision phacoemulsification cataract surgery involves phacoemulsification through a 0.9 millimetre sleeveless phaco tip and irrigating chopper followed by implantation of a rollable intraocular lens. The procedure leads to negligible astigmatism and faster visual recovery as compared to phacoemulsification with a foldable intraocular lens.

Methods

This prospective study analysed 80 cases of sub millimetre phaconit surgery with implantation of rollable intraocular lenses(IOL) in 40 cases and acrylic foldable IOL in the remaining 40 cases. Evaluation of efficacy and adaptability of procedure, equipment settings, operative constraints, postoperative complications, keratometric and topographic evaluation of induced astigmatism with visual outcome and patient''s rehabilitation were studied.

Results

The intraoperative complications were surge/ chamber collapse in 16 (20%), iris chaffing in one and corneal burns in two cases. All cases had an induced astigmatism of less than or equal to ± 0.25 D in four to six weeks after rollable IOL and ± 0.5 D to ± 0.75 D after acrylic IOL implantation. All patients had best-corrected visual acuity of 6/6 by third post operative day.

Conclusion

Phaconit with rollable IOL is a perfect blend of surgical skill, application of technology and ultra thin IOL.Key Words: Phaconit, Ultra micro phaco, Submillimetre incision, Rollable IOL implantation     

Aetiological agents in chronic suppurative otitis media in Sri Lanka

Background

Chronic suppurative otitis media (CSOM) is assumed to be a complication of acute otitis media (AOM), but the risk factors for CSOM are not clear. Objectives: 1. To study the aetiological organisms for CSOM. 2. To identify the effect of demographic factors on disease manifestation.

Method

This retrospective study included a case series of 234 patients who had been admitted to National Hospital of Sri Lanka (NHSL), with the complaint of ear discharge and from whom the specimens were sent for microscopy and culture at Department Of Microbiology, NHSL. The period of analysis was 1 year extending from 1 January 2009 to 31 December 2009.Consecutive patients who fulfilled the inclusion criteria were recruited to the retrospective analysis.

Results

Among 234 patients studied, 129 (55.1%) were male and 150 (64.1%) were under 40 yrs old. The mean age was 39.5 yrs (range 12 to 60 yrs, SD = 22.6). The mean duration of ear discharge was 1.2 yrs. (range 6 weeks to 20 yrs.) Pseudomonas species (29.5%) was the commonest microbial organism to cause ear discharge, followed by staphylococcus (20.5%) and coliform (16.7%) species. Among the fungal agents identified, candida was the most common. 23.1% of the cultures did not reveal any microbiological agent. Eighteen patients (8%) had a prior history of trauma to the affected ear and 51 patients (21.8%) were diagnosed with diabetes mellitus.

Conclusion

The commonest microbial agents implicated in CSOM was pseudomonas species followed by staphylococci and coliforms. Demographic variables such as gender or age did not seem to affect the disease manifestation significantly, though CSOM was less common among elderly and women.     

Evaluation of Vitreous Substitutes in Managing Complicated Vitreo-retinal Surgeries

Background

Vitreous substitutes presently in use for intraoperative tamponade are perfluorocarbon liquids (PFCL) and for post operative tamponade are silicon oil (SO), sulphur hexafluoride (SF₆) and perfluorocarbon gas (PFC). Several factors are important for a thorough understanding of each of these vitreous substitutes. The absorption or necessity for removal, indications for use (including clinical studies and special surgical methods), additives and complications of use have to be considered.

Methods

Three port standard pars plana vitrectomy was performed in 60 consecutive cases requiring intra-vitreal intervention. PFCL was used intra-operatively in 30 cases (PFCL group and X group). The eyes were implanted with SO (silicon oil subgroup), PFC (C₃F₈ sub-group) and SF₆ (SF₆ sub-group) in twenty cases each. Apart from best corrected visual acuity (BCVA), the retinal status and the longevity of gas when used, changes and reaction in both the anterior and posterior segments were noted.

Result

The difference of postoperative BCVA in the PFCL and non-PFCL groups was statistically significant with p < 0.001. In both the PFCL and non-PFCL groups the difference between preoperative and postoperative BCVA was statistically significant with p < 0.0001. All three vitreous substitutes studied are effective given the case where they had been utilised.

Conclusion

PFCL is invaluable in the management of complicated retinal detachment (RD). Where a vitreous microsurgery is indicated, the visual outcome is good. SF₆ is useful for short-term tamponade. Silicon oil and C₃F₈ are useful for longer tamponade.Key Words: Tamponade, Perfluorocarbon liquids, Silicon oil, Sulphur hexafluoride, Perfluorocarbon gas, Retinal detachment