[Functional neuroimaging in patients with rapid cycling bipolar depression]

Bipolar patients with a rapid cycling clinical course constitute an interesting sub-group for studies focused on the pathophysiology of the disorder, since several switches can be studied by the investigators in a short period of time. At present, functional neuroimaging techniques, as SPECT and PET, may be used for the neurobiological study of affective disorders. Few longitudinal functional neuroimaging studies assessing the different phases of bipolar disorder have been carried out. However, the published data suggest an asymmetrical temporal lobe dysfunction in depressive and manic phases of bipolar depression. Further studies with larger samples of patients are needed in order to improve our knowledge of the pathophysiology of bipolar disorder.

Mutations affecting the cAMP transduction pathway modify olfaction in Drosophila

The rutabaga and dunce genes, encode two enzymes of the cyclic adenosine monophosphate transduction pathway in Drosophila, adenylyl cyclase and cyclic adenosine monophosphate phosphodiesterase, respectively. Two main second messenger systems, depending on inositol 1,4,5-triphosphate and cyclic adenosine monophosphate, have been associated with olfaction in vertebrates as well as invertebrates. A relationship between the cyclic adenosine monophosphate signaling pathway and olfactory reception in Drosophila is suggested by the presence of cyclic nucleotide gated channels and cyclic-nucleotide modulated K+ channels in the antennae, the main olfactory organs. In this report, molecular, electrophysiological and behavioral data support the role of cyclic adenosine monophosphate in olfactory function for this species. Expression of both genes in the antennae has been shown by messenger ribonucleic acid analysis. Changes in the electroantennogram kinetics have been observed specifically on the slope of the initial rising phase, as predicted for processes that affect cyclic adenosine monophosphate concentration. Olfactory behavior changes due to both mutations were coherent with a functional meaning of the reported electrophysiological phenotype in olfactory perception. Sensitivity level increases or decreases for the mutants compared to the control line depending on the odorant. These results are compatible with some olfactory coding at the reception level by differential activation of a dual transduction system involving the inositol 1,4,5-triphosphate and cyclic adenosine monophosphate cascades.

Methodologies for estimating disaggregated anthropogenic emissions--application to a coastal Mediterranean region of Spain

Regional estimates of both anthropogenic and biogenic emissions are important inputs for models of atmospheric chemistry. A disaggregated emissions inventory of all relevant pollutants for an area of 100 x 100 km2 centered in Burriana (Castellon, Spain) has been worked out. Time and spatial resolutions were hourly and 1 x 1 km2, respectively. Estimates were made for all relevant sources of anthropogenic emissions. The pollutants considered were SO2, NOx, NMVOCs (nonmethane volatile organic compounds), CH4, CO, CO2, N2O, and NH3. Thus, the emissions inventory includes up to 18 different NMVOCs. Emissions were computed for a typical sunny workday in June when strong photochemical activity could be expected. A "top-down" methodology was applied, taking as a starting point official annual and provincial estimates based on CORINAIR emission factors. This procedure is a very useful tool, particularly for those cases where a lack of sufficient local detailed information about the main emission-generating activities, such as road traffic, makes the use of a "bottom-up" approximation inadvisable. Moreover, updating these emission inventories is easier and they could be used to evaluate the impact of possible abatement strategies.

Stem cells and diabetes

Diabetes mellitus is a metabolic disorder affecting 2-5% of the population. Transplantation of isolated islets of Langerhans from donor pancreata could be a cure for diabetes; however, such an approach is limited by the scarcity of the transplantation material and the long-term side effects of immunosuppressive therapy. These problems may be overcome by using a renewable source of cells, such as islet cells derived from stem cells. Stem cells are defined as clonogenic cells capable of both self-renewal and multilineage differentiation. This mean that these cells can be expanded in vivo or in vitro and differentiated to produce the desired cell type. There exist several sources of stem cells that have been demonstrated to give rise to pluripotent cell lines: 1) embryonic stem cells; 2) embryonic germ cells; 3) embryonic carcinoma cells; and 4) adult stem cells. By using in vitro differentiation and selection protocols, embryonic stem cells can be guided into specific cell lineages and selected by applying genetic selection when a marker gene is expressed. Recently, differentiation and cell selection protocols have been used to generate embryonic stem cell-derived insulin-secreting cells that normalise blood glucose when transplanted into diabetic animals. Some recent reports suggest that functional plasticity of adult stem cells may be greater than expected. The use of adult stem cells will circumvent the ethical dilemma surrounding embryonic stem cells and will allow autotransplantation. These investigations have increased the expectations that cell therapy could be one of the solutions to diabetes.

From stem cells to beta cells: new strategies in cell therapy of diabetes mellitus

Islet transplantation as a potential treatment for diabetes has been investigated extensively over the past 10 years. Such an approach, however, will always be limited mainly because it is difficult to obtain sufficiently large numbers of purified islets from cadaveric donors. One alternative to organ or tissue transplantation is to use a renewable source of cells. Stem cells are clonogenic cells capable of both self-renewal and multilineage differentiation. These cells have the potential to proliferate and differentiate into any type of cell and to be genetically modified in vitro, thus providing cells which can be isolated and used for transplantation. Recent studies have given well-defined differentiation protocols, which can be used to guide stem cells into specific cell lineages as neurons, cardiomyocytes and insulin-secreting cells. Moreover, these derived cells have been useful in different animal models. In this regard, insulin-secreting cells derived from R1 mouse embryonic stem cells restore blood glucose concentrations to normal when they are transplanted into streptozotocin-induced diabetic animals. These results show that diabetes could be among the first applications of stem cell therapy.

Noninvasive assessment of cardiac risk in type I diabetic patients being evaluated for combined pancreas-kidney transplantation using dipyridamole-MIBI perfusion tomographic scintigraphy

This study was performed to determine the value of dipyridamole-99m Tc-methoxy-isobutyl isonitrile perfusion (99mTC-MIBI) tomographic scintigraphy in the assessment of cardiac risk in patients being evaluated prior to combined pancreas-kidney transplantation (PKT). We performed perfusion tomographic scintigraphy using single photon emission computed tomography (SPECT) on 77 patients. The tomographic images did not show clinically relevant findings in 65 patients. In the remaining 12 patients, coronary arteriography was performed: 2 showed normal results, 4 showed no stenosis, and 6 showed significant stenosis ( > or = 70%). Seventy-two patients underwent PKT. During the follow-up (6-48 months), there were seven cardiac events, 4 patients with significant stenosis, and 3 with nonsignificant stenosis upon coronary arteriography, and all had pathological tomographic images. 99mTc-MIBI tomographic scintigraphy may be useful in identifying patients at low risk of incurring cardiac events after PKT and may, in a large group of patients, obviate the need for routine coronary angiography.

Sentinel lymph node biopsy in breast cancer patients: subdermal versus peritumoural radiocolloid injection

BACKGROUND AND AIMS

Sentinel lymph node (SLN) biopsy has been widely used in the management of melanoma and breast cancer. The aims of this study were (1) to compare the results obtained with the two main injection techniques, the peritumoural and subdermal; and (2) to determine the reliability of SLN to predict the regional lymph node status.

METHOD

We prospectively studied 80 women (mean age 56 years) with breast cancer. Thirty-four of them were T1 and the remaining 46 were T2. Patients were divided into two groups. Group A, 36 patients were injected subdermally, surrounding the tumour site. Group B, 44 patients were injected peritumourally guided by ultrasound if non-palpable. Planar images were performed 15 min after the injection and continued until SLN identification. Before surgery, blue dye injection was administered similarly to the radiocolloid. After incision, a hand-held gamma probe was used to reach the SLN. All nodes harvested were analysed by classic pathology techniques.

RESULTS

Overall, lymphoscintigraphy allowed the detection of SLN in 75/80 patients (94%). All subdermal lymphoscintigraphies were positive (36/36) compared with 89% of peritumoural (39/44). Blue dye detected SLN in 23/31 patients (74%) after subdermal injection and in 24/34 patients (71%) after peritumoural injection. The sensitivity to localize the SLN with lymphoscintigraphy+blue dye+gamma probe was 92% (33/36) within the subdermal group and 91% (40/44) within the peritumoural group. Overall, five false negative SLN were found. All of these corresponded to T2 tumours with a size greater than 2.5 cm. The negative predictive value and the accuracy were 93% and 94%, respectively, for the subdermal group and 90% and 93% for the peritumoural group.

CONCLUSIONS

(1) Our results indicate that both techniques have similar results. However, we suggest that T2 tumours with a size greater than 2.5 cm should be excluded from the SLN technique, in order to improve the accuracy and negative predictive value. (2) Lymphoscintigraphy is essential for visualizing the SLN, and blue dye can be helpful when the gamma probe does not localize the SLN.

[Late hepatitis C virus seroconversion in a patient on hemodialysis]

We present a case of an exceptionally late HCV seroconversion in a hemodialysis patient. The clinical case illustrates the difficulty of appropriately and quickly isolating a HCV infected patient, and it demonstrates the necessity to consider all the dialysis patients as potentially infectious patients. The standard precautions in hemodialysis must be applied routinely to all the patients, because the diagnosis of the HCV infection is very often late, and on some occasions it is difficult to interpret correctly the results of the available diagnostic tests.

Arthroscopic repair of the posterior cruciate ligament: two techniques

SUMMARY

Isolated posterior cruciate ligament injuries are rare and their treatment is controversial. These lesions have commonly been treated by open reduction and internal fixation using a posterior approach. However, this approach makes it difficult to explore other combined injuries of the knee joint. We report 2 cases of posterior cruciate ligament avulsion of the tibia that were arthroscopically reduced and fixed using 2 different methods, cannulated screws and tension band wire.

[Treatment of metastatic bone pain with repeated doses of strontium-89 in patients with prostate neoplasm]

This study has aimed to evaluate the usefulness of repeated treatment with 89Sr in patients with prostate neoplasm and metastatic bone pain. Seventeen patients with partial or complete response after the first dose were retreated with two or more doses (total of 39 doses). The Karnofsky functional status, pain and degree of analgesia were assessed. After the first dose the response was good in 68% of the patients and partial in 32%. After the second dose, the response was good in 62% of the patients, partial in 15% and there was no response in 23% of the cases. The pre-treatment Karnofsky functional status and duration of the effect of 89Sr was lower after the second dose (p = 0.03, p = 0.02), but there were no statistically significant differences in the type of response. In conclusion, re-treatment with 89Sr can be administered safely and with a similar response to that achieved after the first dose.

Junctional communication of pancreatic beta cells contributes to the control of insulin secretion and glucose tolerance

Proper insulin secretion requires the coordinated functioning of the numerous beta cells that form pancreatic islets. This coordination depends on a network of communication mechanisms whereby beta cells interact with extracellular signals and adjacent cells via connexin channels. To assess whether connexin-dependent communication plays a role in vivo, we have developed transgenic mice in which connexin 32 (Cx32), one of the vertebrate connexins found in the pancreas, is expressed in beta cells. We show that the altered beta-cell coupling that results from this expression causes reduced insulin secretion in response to physiologically relevant concentrations of glucose and abnormal tolerance to the sugar. These alterations were observed in spite of normal numbers of islets, increased insulin content, and preserved secretory response to glucose by individual beta cells. Moreover, glucose-stimulated islets showed improved electrical synchronization of these cells and increased cytosolic levels of Ca(2+). The results show that connexins contribute to the control of beta cells in vivo and that their excess is detrimental for insulin secretion.

Usefulness of strontium-89 for bone pain palliation in metastatic breast cancer patients

Most studies of prostate cancer have shown that strontium-89 chloride (89Sr) is effective in the palliation of metastatic bone pain, refractory to conventional analgesia. The aim of this study was to evaluate the usefulness of 89Sr for bone pain palliation in breast cancer patients. Forty women were treated with 148 MBq of 89Sr. Six patients were retreated, receiving two or more doses. The Karnofsky performance status was assessed and pain and analgesia were scored on scales of 9 and 5 points, respectively. The efficacy of 89Sr was evaluated at 3 months of treatment. The response was good in 60% of the patients and partial in 32%; there was no response in the remaining 8% (pre-treatment Karnofsky < or = 60). The duration of the response was 120+/-143 days. In the patients retreated, the response was good in 83% and partial in 17%, without significant differences compared with the first dose, but the pre-treatment Karnofsky and the duration of the efficacy were lower (P < 0.05). A transient and slight decrease of leukocyte and platelet counts after the first month of treatment with 59Sr was observed. In conclusion, breast cancer patients with metastatic bone pain can benefit from therapy with 89Sr. If necessary, the treatment may be repeated safely and with the same efficacy as is achieved after the first dose. A low functional performance status could be a cause of the lower effectiveness of 89Sr.

Nutrient toxicity in pancreatic beta-cell dysfunction

Nutrients, such as glucose and fatty acids, have a dual effect on pancreatic beta-cell function. Acute administration of high glucose concentrations to pancreatic beta-cells stimulates insulin secretion. In addition, short term exposure of this cell type to dietary fatty acids potentiates glucose-induced insulin release. On the other hand, long-term exposure to these nutrients causes impaired insulin secretion, characterized by elevated exocytosis at low concentrations of glucose and no response when glucose increases in the extracellular medium. In addition, other phenotypic changes are observed in these conditions. One major step in linking these phenotypic changes to the diabetic pathology has been the recognition of both glucose and fatty acids as key modulators of beta-cell gene expression. This could explain the adaptative response of the cell to sustained nutrient concentration. Once this phase is exhausted, the beta-cell becomes progressively unresponsive to glucose and this alteration is accompanied by the irreversible induction of apoptotic programs. The aim of this review is to present actual data concerning the development of the toxicity to the main nutrients glucose and fatty acids in the pancreatic beta-cell and to find a possible link to the development of type 2 diabetes.

Nutrient modulation of polarized and sustained submembrane Ca2+ microgradients in mouse pancreatic islet cells

The intracellular calcium concentration ([Ca2+]i) near the plasma membrane was measured in mouse pancreatic islet cells using confocal spot detection methods. Whereas small cytosolic Ca2+ gradients were observed with 3 mM glucose, a steeper sustained gradient restricted to domains beneath the plasma membrane (space constant, 0.67 micrometer) appeared with 16.7 mM glucose. When the membrane potential was clamped with increasing K+ concentrations (5, 20 and 40 mM), no [Ca2+]i gradients were observed in any case. Increasing glucose concentration (0, 5 and 16.7 mM) in the presence of 100 microM diazoxide, a K+ channel opener, plus 40 mM K+ induced steeper [Ca2+]i gradients, confirming the role of membrane potential-independent effects of glucose. Prevention of Ca2+ store refilling with 30 microM cyclopiazonic acid (CPA) or blockade of uniporter-mediated Ca2+ influx into the mitochondria with 1 microM carbonyl cyanide m-chlorophenyl hydrazone (CCCP) or 1 microM Ru-360 significantly reduced the steepness of the 16.7 mM glucose-induced [Ca2+]i gradients. Measured values of [Ca2+]i reached 6.74 +/- 0.67 microM at a distance of 0.5 micrometer from the plasma membrane and decayed to 0.27 +/- 0.03 microM at a distance of 2 micrometer. Mathematically processed values at 0.25 and 0 micrometer gave a higher [Ca2+]i, reaching 8.18 +/- 0.86 and 10.05 +/- 0.98 microM, respectively. The results presented indicate that glucose metabolism generates [Ca2+]i microgradients, which reach values of around 10 microM, and whose regulation requires the involvement of both mitochondrial Ca2+ uptake and endoplasmic reticulum Ca2+ stores.

[Perforating epicardial lead: atypical evolution]

Endocarditis related to pacemaker lead is a rare complication of permanent transvenous pacing, of which the diagnosis is carried out with the presence of verrucae in echocardiography and positive blood cultures, its treatment being mixed -medical and surgical- because the isolated medical treatment is rarely successful and the lead should be extracted. We present the case of recurrent endocarditis of several years of evolution, in the which it was not possible to extract of the electrode due to the special characteristics of the patiente (epicardial lead perforating into right atrial).

Engineering pancreatic islets

Pancreatic islets are neuroendocrine organs that control blood glucose homeostasis. The precise interplay of a heterogeneous group of cell populations (beta, alpha, delta and PP cells) results in the fine-tuned release of counterbalanced hormones (insulin, glucagon, somatostatin and pancreatic polypeptide respectively). Under the premises of detailed knowledge of the physiological basis underlying this behaviour, two lines of investigation might be inferred: generating computational and operational models to explain and predict this behaviour and engineering islet cells to reconstruct pancreatic endocrine function. Whilst the former is being fuelled by new computational strategies, giving biophysicists the possibility of modelling a system in which new "emergent" properties appear, the latter is benefiting from the useful tools and strategic knowledge achieved by molecular, cell and developmental biologists. This includes using tumour cell lines, engineering islet cell precursors, knowledge of the mechanisms of differentiation, regeneration and growth and, finally, therapeutic cloning of human tissues. Gaining deep physiological understanding of the basis governing these processes is instrumental for engineering new pancreatic islets.

[Undiagnosed diabetes and impaired glucose metabolism on high risk Spanish population. The IGT study]

BACKGROUND

To estimate the prevalence of undiagnosed diabetes and impaired glucose metabolism on high risk Spanish population, contrasting phenotypic features according to both sets of criteria, World Health Organization (WHO) and American Diabetes Association (ADA).

SUBJECTS AND METHODS

Cross-sectional, multicentre (10 health-care centres, 230,000 inhabitants), selective risk-factor study. WHO diagnoses (normal, impaired glucose tolerance [IGT] and diabetes) were based on the 2 h plasma glucose (2hPG) following a 75 g oral glucose tolerance test (OGTT) and ADA diagnoses according the fasting plasma glucose (FPG) (normal, impaired FPG and diabetes). Prevalence, diagnostic overlap index and 22 clinical and biological parameters were compared.

RESULTS

The study included 580 subjects (330 women), mean age 58.1 years and body mass index 31.2 kg/m2, 292 (50.3%) with only one risk factor and 288 (49.7%) with two or more risk factors. WHO diagnoses were: 291 (50.2%) normal glucose tolerance (95% CI: 46.2-54.2%), 157 (27.1%) IGT (23.5-30.7%) and 132 (22.7%) diabetes (19.3-26.1%). ADA diagnoses were: 355 (61.2%) normal FPG (57.2-65.2%), 146 (25.2%) IFG (21.7-28.7%) and 79 (13.6%) diabetes (10.9-16.3%). The prevalence of diabetes decreased 9.1% (from -11.4 to -6.8%). The diagnostic overlap was 33.5% for diabetes and 19.3% for impaired glucose homeostasis (IGT-FPG). Omitting the OGTT half the diabetic subjects with 2hPG > or = 200 mg/dl (11.1 mM) but FPG < 126 mg/dl (7 mM) would remain undiagnosed. By changing screening criteria (FPG instead of 2hPG) the risk related to traditional factors such as age or a first-degree relative with diabetes would reduce.

CONCLUSIONS

Applying ADA criteria, the high prevalence of undiagnosed glucose abnormalities would decrease. These results suggest that it is strongly advisable the continued use of the 2hPG for diabetes screening on high risk Spanish population.

Insulin-secreting cells derived from embryonic stem cells normalize glycemia in streptozotocin-induced diabetic mice

Embryonic stem (ES) cells display the ability to differentiate in vitro into a variety of cell lineages. Using a cell-trapping system, we have obtained an insulin-secreting cell clone from undifferentiated ES cells. The construction used allows the expression of a neomycin selection system under the control of the regulatory regions of the human insulin gene. The chimeric gene also contained a hygromycin resistance gene (pGK-hygro) to select transfected cells. A resulting clone (IB/3x-99) containing 16.5 ng/microg protein of total insulin displays regulated hormone secretion in vitro in the presence of various secretagogues. Clusters obtained from this clone were implanted (1 x 10(6) cells) in the spleen of streptozotocin-induced diabetic animals. Transplanted animals correct hyperglycemia within 1 week and restore body weight in 4 weeks. Whereas an intraperitoneal glucose tolerance test showed a slower recovery in transplanted versus control mice, blood glucose normalization after a challenge meal was similar. This approach opens new possibilities for tissue transplantation in the treatment of type 1 and type 2 diabetes and offers an alternative to gene therapy.