Chronic Kidney Disease in the Caribbean Island of Antigua: Causes, Morbidity and Mortality Factors / Enfermedad renal crónica en la isla caribeña de Antigua: causas, morbilidad y factores de mortalidad

ABSTRACT Background: Chronic kidney disease (CKD) and its associated high morbidity and mortality cause a significant economic burden and decreased quality of life in affected patients in Antigua, the rest of the Caribbean and globally. The causes of CKD in Antigua, morbidity and mortality factors affecting the sampled patients were evaluated with a view to formulating interventions to minimize the occurrence and the impact of these factors. Objective: To determine the causes of CKD over a nine-year period and the causes of morbidity and mortality among patients with CKD at the two main hospitals in Antigua. Methods: A retrospective review was done of the medical records of patients with CKD who were diagnosed between January 1, 2005 and December 1, 2013. Chronic kidney disease was defined as a glomerular filtration rate of less than 60 mL/minute/1.73 m2. The causes of CKD, the patients 'admission diagnoses, the causes of death and laboratory investigations were evaluated. Results: The documented causes of CKD in these patients were diabetes mellitus (51% of the patients), hypertension (26%), glomerulonephritis (5%) and lupus nephritis (4%). The causes of morbidity among the patients with CKD were myocardial infarction (5.1%), unstable angina (12.7%) and ischaemic stroke (12%). Contributing significantly to the patients 'morbidity were catheter-associated sepsis (8.1%, p < 0.001) and lower respiratory tract infections (5.4%). The main factors contributing to the patients 'mortality were myocardial infarction (16.7%) and catheter-associated sepsis (16.7%). Conclusion: This study documented that the most common causes of CKD among the sampled patients in Antigua were diabetes mellitus and hypertension. Ischaemic heart disease and infections were the major causes of morbidity and mortality among the patients. Early recognition and aggressive management of CKD and its risk factors and complications are important in reducing the clinical and economic burden associated with CKD.

RESUMEN Antecedentes: La enfermedad renal crónica (ERC) y su alta morbilidad y mortalidad asociadas, son causa de una importante carga económica y disminución de la calidad de vida entre los pacientes afectados en Antigua, el resto del Caribe y en todo el mundo. Se evaluaron las causas de la ERC en Antigua, así como los factores de morbilidad y mortalidad que afectan a los pacientes muestreados, con el fin de formular intervenciones encaminadas a minimizar la ocurrencia y el impacto de estos factores. Objetivo: Determinar las causas de la ERC durante un período de nueve años y las causas de morbilidad y mortalidad entre pacientes con ERC en los dos principales hospitales de Antigua. Métodos: Se realizó una revisión retrospectiva de las historias clínicas de los pacientes con ERC diagnosticados entre el 1 de enero de 2005 y el 1 de diciembre de 2013. La enfermedad renal crónica se definió como una tasa de filtración glomerular inferior a 60 ml/minuto/1.73 m2. Se evaluaron las causas de la ERC, los diagnósticos de admisión de los pacientes, así como las causas de muerte y las investigaciones de laboratorio. Resultados: Las causas documentadas de la ERC en estos pacientes fueron la diabetes mellitus (51% de los pacientes), la hipertensión (26%), la glomerulonefritis (5%), y la nefritis lúpica (4%). Las causas de morbilidad entre los pacientes con ERC fueron el infarto de miocardio (5.1%), la angina inestable (12.7%) y el accidente cerebrovascular isquémico (12%). La sepsis asociada con catéter (8.1%, p < 0.001) y las infecciones de las vías respiratorias inferiores (5.4%) contribuyeron significativamente a la morbilidad de los pacientes. Los principales factores que contribuyeron a la mortalidad de los pacientes fueron el infarto del miocardio (16.7%) y la sepsis asociada con catéter (16.7%). Conclusión: Este estudio documentó que las causas más comunes de ERC entre los pacientes incluidos en la muestra en Antigua fueron la diabetes mellitus y la hipertensión. La enfermedad cardíaca isquémica y las infecciones fueron las principales causas de morbilidad y mortalidad entre los pacientes. El diagnóstico temprano y el tratamiento agresivo de la ERC y sus factores y complicaciones de riesgo, son asuntos de importancia a la hora de reducir la carga clínica y económica asociadas con ERC.

Single-step separation of platelets from whole blood coupled with digital quantification by interfacial platelet cytometry (iPC).

We report the efficient single-step separation of individual platelets from unprocessed whole blood, enabling digital quantification of platelet function using interfacial platelet cytometry (iPC) on a chip. iPC is accomplished by the precision micropatterning of platelet-specific protein surfaces on solid substrates. By separating platelets from whole blood using specific binding to protein spots of a defined size, iPC implements a simple incubate-and-rinse approach, without sample preparation, that enables (1) the study of platelets in the physiological situation of interaction with a protein surface, (2) the choice of the number of platelets bound on each protein spot, from one to many, (3) control of the platelet-platelet distance, including the possibility to study noninteracting single platelets, (4) digital quantification (counting) of platelet adhesion to selected protein matrices, enabling statistical characterization of platelet subpopulations from meaningfully large numbers of single platelets, (5) the study of platelet receptor expression and spatial distribution, and (6) a detailed study of the morphology of isolated single platelets at activation levels that can be manipulated. To date, we have demonstrated 1-4 of the above list. Platelets were separated from whole blood using iPC with fibrinogen, von Willebrand factor (VWF), and anti-CD42b antibody printed "spots" ranging from a fraction of one to several platelet diameters (2-24 µm). The number of platelets captured per spot depends strongly on the protein matrix and the surface area of the spot, together with the platelet volume, morphology, and activation state. Blood samples from healthy donors, a May-Hegglin-anomaly patient, and a Glanzmann's Thrombasthenia patient were analyzed via iPC to confirm the specificity of the interaction between protein matrices and platelets. For example, the results indicate that platelets interact with fibrinogen spots only through the fibrinogen receptor (αIIbß3) and, relevant to diagnostic applications, platelet adhesion correlates strongly with normal versus abnormal platelet function. A critical function of platelets is to adhere to regions of damage on blood vessel walls; in contrast to conventional flow cytometry, where platelets are suspended in solution, iPC enables physiologically relevant platelet bioassays based on platelet/protein-matrix interactions on surfaces. This technology should be inexpensive to implement in clinical assay format, is readily integrable into fluidic microdevices, and paves the way for high-throughput platelet assays from microliter volumes of whole blood.

A novel functional role for the highly conserved alpha-subunit KVGFFKR motif distinct from integrin alphaIIbbeta3 activation processes.

BACKGROUND: The highly conserved integrin alpha-subunit membrane-proximal motif KVGFFKR plays a decisive role in modulating the activation of integrin alphaIIbbeta3. Previously, we have shown that a platelet permeable palmityl (pal)-peptide with this seven amino acid sequence can directly activate alphaIIbbeta3 leading to platelet aggregation. OBJECTIVES: To investigate further the role of the KVGFFKR motif in integrin alphaIIbbeta3 function. METHODS: We used two sequence-specific complementary model systems, palmityl pal-peptides in platelets, and mutant alphaIIbbeta3-expressing Chinese Hamster Ovary (CHO) cell lines. RESULTS: In platelets we show that the two phenylalanine amino acids in pal-KVGFFKR (pal-FF) peptide are critical for stimulating platelet aggregation. Pal-FF peptide treatment of platelets also gives rise to a tyrosine phosphorylation signal despite the presence of inhibitors of fibrinogen binding. In CHO cells, a double alanine substitution, alphaIIb(F992A, F993A)beta3, induces constitutive integrin activation but prevents actin stress fiber formation upon adhesion to fibrinogen, suggesting that alphaIIbbeta3-mediated cytoskeletal reorganization is also dependent on F992 and F993. This further highlights a critical role for the two phenylalanine residues in both of these alphaIIbbeta3-mediated processes. CONCLUSION: In addition to regulating integrin alphaIIbbeta3 activation state, the KVGFFKR motif also influences cytoskeletal reorganization. This activity is critically determined by F992 and F993 within the seven amino acid sequence.

Evidence for a differential functional regulation of the two beta(3)-integrins alpha(V)beta(3) and alpha(IIb)beta(3).

The functional regulation of integrins is a major determinant of cell adhesion, migration and tissue maintenance. The binding of cytoskeletal proteins to various sites of integrin cytoplasmic domains is a key mechanism of this functional regulation. Expression of recombinant integrin alpha(IIb)beta(3) and alpha(M)beta(2) lacking the GFFKR-region in CHO cells results in constitutively activated integrins. In contrast, CHO cells stably expressing either a GFFKR-deleted alpha(V(del))beta(3) or a FF to AA-substituted alpha(V(AA))beta(3) do not reveal a constitutively activated integrin. Adhesion to immobilized fibrinogen is strongly impaired in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells, whereas it is not impaired in alpha(IIb)beta(3) and alpha(M)beta(2), both lacking the GFFKR-region. In a parallel plate flow chamber assay, alpha(V)beta(3)-expressing cells adhere firmly to fibrinogen and spread even at shear rates of 15 to 20 dyn/cm(2), whereas alpha(V(del))beta(3) or alpha(V(AA))beta(3) cells are detached at 15 dyn/cm(2). Actin stress fiber formation and focal adhesion plaques containing alpha(V)beta(3) are observed in alpha(V)beta(3) cells but not in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells. As an additional manifestation of impaired outside-in signaling, phosphorylation of pp125(FAK) was reduced in these cells. In summary, we report that the GFFKR-region of the alpha(V)-cytoplasmic domain and in particular two phenylalanines are essential for integrin alpha(V)beta(3) function, especially for outside-in signaling. Our results suggest that the two beta(3)-integrins alpha(IIb)beta(3) and alpha(V)beta(3) are differentially regulated via their GFFKR-region.

A palmitylated peptide derived from the glycoprotein Ib beta cytoplasmic tail inhibits platelet activation.

The platelet receptor GPIb/IX/V mediates a crucial role in hemostasis, yet the signaling mechanisms involved are incompletely understood. The complex consists of four polypeptides GPIb alpha, GPIb beta, GPIX and GPV. We identified an amino acid sequence in the cytoplasmic tail of the GPIb beta subunit between residues R151 and A161 that is highly conserved across species and hypothesized that it has functional importance. To target this motif, we synthesized a corresponding cell-permeable palmitylated peptide (Pal-RRLRARARARA) and investigated its effect on platelet function. Pal-RRLRARARARA completely inhibited low dose thrombin- and ristocetin-induced aggregation in washed platelets but only partially inhibited collagen- and U46619-induced aggregation. Thromboxane production in platelets stimulated with thrombin was significantly reduced by Pal-RRLRARARARA compared with collagen. Activation of the integrin alpha IIb beta 3 in response to thrombin was significantly reduced when platelets were preincubated with Pal-RRLRARARARA. The adhesion of washed platelets to von Willebrand factor (VWF) under static conditions was significantly reduced by Pal-RRLRARARARA. Under conditions of high shear, the velocity of platelets rolling on VWF was significantly increased when platelets are preincubated with Pal-RRLRARARARA. This study defines a novel function for the RRLRARARARA motif of GPIb beta in platelet activation.

Structure, function and evolution of glutathione transferases: implications for classification of non-mammalian members of an ancient enzyme superfamily.

The glutathione transferases (GSTs; also known as glutathione S-transferases) are major phase II detoxification enzymes found mainly in the cytosol. In addition to their role in catalysing the conjugation of electrophilic substrates to glutathione (GSH), these enzymes also carry out a range of other functions. They have peroxidase and isomerase activities, they can inhibit the Jun N-terminal kinase (thus protecting cells against H(2)O(2)-induced cell death), and they are able to bind non-catalytically a wide range of endogenous and exogenous ligands. Cytosolic GSTs of mammals have been particularly well characterized, and were originally classified into Alpha, Mu, Pi and Theta classes on the basis of a combination of criteria such as substrate/inhibitor specificity, primary and tertiary structure similarities and immunological identity. Non-mammalian GSTs have been much less well characterized, but have provided a disproportionately large number of three-dimensional structures, thus extending our structure-function knowledge of the superfamily as a whole. Moreover, several novel classes identified in non-mammalian species have been subsequently identified in mammals, sometimes carrying out functions not previously associated with GSTs. These studies have revealed that the GSTs comprise a widespread and highly versatile superfamily which show similarities to non-GST stress-related proteins. Independent classification systems have arisen for groups of organisms such as plants and insects. This review surveys the classification of GSTs in non-mammalian sources, such as bacteria, fungi, plants, insects and helminths, and attempts to relate them to the more mainstream classification system for mammalian enzymes. The implications of this classification with regard to the evolution of GSTs are discussed.

Chemical modulation of chemotherapy resistance in cultured oesophageal carcinoma cells.

Oesophageal carcinoma is a common form of cancer in developing countries, especially in the Caspian littoral and northern China. In contrast, it has a much lower incidence in Japan, the U.S.A. and western Europe. Certainly in the case of squamous cell oesophageal carcinoma, dietary composition, smoking, alcohol and exposure to nitrosamines are major risk factors that may partly explain the disease's geographical distribution. The prognosis for oesophageal carcinoma is generally poor, due to the high incidence of distant metastasis and local recurrence. Combination treatment with both cisplatin and 5-fluorouracil is the most common chemotherapy regime used. We have carried out a detailed study of sensitivity of two oesophageal cell lines: OC1 cells from a squamous carcinoma of a male patient, and OC2, a squamous carcinoma obtained from a female patient. Both cell lines are sensitive to Vinca alkaloids and doxorubicin, while being quite resistant to alkylating agents such as cisplatin and 1,3-bis-(2-chloroethyl)-1-nitrosourea. This pattern of resistance suggests a possible role for glutathione S-transferase (GST) and/or glutathione (GSH) in resistance, and would seem to exclude the multidrug resistance phenotype. Both cell lines possess mainly Pi-class GSTs, and have distinct levels of GSH, with OC2 possessing some 25% of the level of OC1 cells. Effects of a variety of modulating agents on the pattern of resistance, such as the GSH depleter, buthionine sulphoximine, and the GST inhibitor, ethacrynic acid, were determined. An unexpected observation was that ethacrynic acid appears to increase the level of GSH in both cell lines.

Use of ambroxol and bromhexine as mucolytics for enhanced diffusion of furaltadone into tracheobronchial secretions in broilers.

1. Ambroxol and bromhexine were evaluated as mucolytics and to enhance the passage of furaltadone into tracheobronchial secretions (TBS) in chronic complicated respiratory disease-affected broilers. 2. Viscosity of TBS was noticeably increased in the ambroxol-treated birds and only slightly increased in the bromhexine groups; however, the physical (nature) of TBS was superior in the ambroxol-treated broilers. 3. There was a clear increase in the passage of furaltadone into tracheobronchial secretions only in the ambroxol-treated birds. 4. Everyday use of ambroxol in broilers is discussed.

The solubility of calcium and phosphorus in neonatal total parenteral nutrition solutions.

Precipitation of calcium phosphate in neonatal total parenteral nutrition (TPN) solutions remains a significant problem. Whereas numerous studies have attempted to establish guidelines for maximum concentrations of various combinations that can be mixed, differences in study design and reliance upon subjective visual assessment severely limit their applicability. The purpose of this study was to quantitatively determine calcium and phosphate compatibility in commonly used neonatal TPN solutions containing a final concentration of either 1 or 2% amino acids. The final dextrose concentration was 10%. Electrolytes, heparin, and pediatric vitamins and trace minerals were also added. Calcium gluconate (10%) and potassium phosphate (mono and dibasic) were added by calibrated micropipetors. Calcium concentrations ranged from 5 to 60 mEq/L and phosphate from 5 to 40 mM/L with a minimum of 84 combinations tested for each amino acid concentration. Calcium concentrations were measured in duplicate for each tested combination. Control solutions containing calcium but no phosphate were included to validate the assay methodology. All samples were stored at room temperature for 23.5 hours and then placed in a water bath at 37 degrees C for 30 minutes to simulate incubator conditions encountered during TPN infusion. Calcium determinations were then repeated and precipitation was judged to have occurred whenever calcium concentrations fell below 90% of the initial measured values. These data allowed plotting a calcium and phosphorus reference curve for TPN solutions containing 1 and 2% amino acids based on quantitative assessment. These reference curves should allow pharmacists to avoid compounding TPN solutions that will precipitate, thus saving considerable cost to the pharmacy and preventing complications.