Una aproximación actualizada hacia el tratamiento de la esclerosis múltiple / An updated approach to the treatment of multiple sclerosis

La presente es una revisión bibliográfica actualizada sobre el manejo de la Esclerosis Múltiple (EM), enfermedad neurológica progresiva de tipo desmielinizante más frecuente a nivel mundial. En Chile, su presentación remitente-recurrente (RRMS) es patología GES, por lo que se vuelve relevante para el médico general y estudiantes del área de la salud reconocer e identificar las terapias disponibles para el control de esta patología. Si bien la EM no es un cuadro frecuente, su sintomatología es alarmante e incapacitante, por lo que, con frecuencia, el primer acercamiento del paciente es a los servicios de urgencia, tornándose necesario contar con nociones básicas sobre el tratamiento y manejo. La presente revisión recopiló artículos publicados entre 2019 y 2023 de distintos motores de búsqueda con énfasis en el tratamiento farmacológico y no farmacológico de esta enfermedad. Además de describir el tratamiento convencional como la inmunomodulación, las terapias biológicas, el soporte con glucocorticoides y los fármacos remielinizantes, se abordan nuevas líneas de investigación prometedoras, como el rol inmunogénico de la microbiota intestinal, la capacidad epigenética de la dieta, estrategias de rehabilitación cognitiva y el potencial uso de cannabinoides para el manejo paliativo del dolor. Se concluye que un tratamiento oportuno con fármacos modificadores de la enfermedad, tanto de primera línea como de segunda, son imprescindibles para el manejo de la EM, sin embargo, la calidad de vida puede verse significativamente acrecentada por la incorporación de estrategias que se encuentran al alcance del médico general y que no requieren de derivación a nivel secundario.

This is an updated bibliographical review on the management of Multiple Sclerosis (MS), the most common progressive neurological disease of demyelinating disorders worldwide. In Chile, its relapsing-remitting presentation (RRMS) is a state-covered illness pathology, so it becomes relevant for the general practitioner and med students to recognize and identify therapies available for the control of this desease. Although MS is not a frequent condition, its symptoms are alarming and disabling, which is why, frequently, the first approach of the patient is to the emergency services, making it necessary to have basic knowledge about treatment and management. The present review compiled articles published between 2019 and 2023 from different search engines with an emphasis on the pharmacological and non-pharmacological treatment of the MS. In addition to describing conventional treatment such as immunomodulation, biological therapies, glucocorticoid support and remyelinating drugs, new promising lines of research are addressed, such as the immunogenic role of the intestinal microbiota, the epigenetic capacity of the diet, strategies on cognition rehabilitation and the potential use of cannabinoids for the palliative management of pain. It is concluded that the classic treatment with disease-modifying drugs, both first-line and second-line, are essential for the management of MS; however, quality of life can be significantly increased by incorporating strategies found at the reach of the general practitioner and do not require referral at a greater complexity center.

Ex vivo treatment with fucoidan of mononuclear cells from SARS-CoV-2 infected patients.

COVID-19 is a worldwide health emergency, therapy for this disease is based on antiviral drugs and immunomodulators, however, there is no treatment to effectively reduce the COVID-19 mortality rate. Fucoidan is a polysaccharide obtained from marine brown algae, with anti-inflammatory, antiviral, and immune-enhancing properties, thus, fucoidan may be used as an alternative treatment (complementary to prescribed medical therapy) for the recovery of COVID-19.  This work aimed to determine the effects of ex-vivo treatment with fucoidan on cytotoxicity, apoptosis, necrosis, and senescence, besides functional parameters of calcium flux and mitochondrial membrane potential (ΔΨm) on human peripheral blood mononuclear cells isolated from SARS-CoV-2 infected, recovered and healthy subjects. Data suggest that fucoidan does not exert cytotoxicity or senescence, however, it induces the increment of intracellular calcium flux. Additionally, fucoidan promotes recovery of ΔΨm in PBMCs from COVID-19 recovered females. Data suggest that fucoidan could ameliorate the immune response in COVID-19 patients.

Supplementation with Phaseolus vulgaris Leaves Improves Metabolic Alterations Induced by High-Fat/Fructose Diet in Rats Under Time-Restricted Feeding.

Time-restricted feeding and food enriched in polyphenols are strategies to prevent or reduce metabolic disorders. Bean leaves (Phaseolus vulgaris L.) are a recognized source of polyphenolic compounds, whose effects on metabolic pathways are not well studied. We evaluated the combined effects of dietary supplementation with Phaseolus vulgaris leaves (10% w/w) (BL) and a 7-h daytime-restricted feeding protocol (RF) under a hypercaloric diet (high fat + high fructose) (HFFD) on the metabolic parameters related to glucose and lipid handling. Adult male Wistar rats were treated for 8 weeks with standard and HFFD diets with or without BL. The results showed that RF improved metabolic alterations induced by HFFD (e.g., hepatic steatosis, increased triacylglycerols, and serum lipoproteins). Supplementation with BL significantly enhanced this effect and downregulated the mRNA expression of carbohydrate and lipid metabolism genes in the liver. These results indicate that dietary supplementation with BL enhances the benefits elicited by RF.

Urinary sepsis after endourological ureterorenoscopy for the treatment of lithiasis. / Sepsis urinaria tras tratamiento endourológico de la litiasis por ureterorrenoscopia.

OBJECTIVE: To evaluate the incidence, clinical presentation and factors associated with the development of urinary sepsis after performing ureterorenoscopy. MATERIAL AND METHODS: Retrospective study of patients undergoing ureterorenoscopy for the treatment of lithiasis between July 2015 and October 2017. Patients who developed urinary sepsis during the 30 days following the intervention were identified. Personal, clinical, surgical and microbiological backgrounds were collected. Statistical analysis was performed with the Chi squared test (or Fisher's exact test), Student's t (or U Mann-Whitney) or logistic regression as appropriate. RESULTS: 246 ureterorenoscopies were performed, 184 (74.8%) on ureteral stones and 62 (25.2%) on kidney stones, with a mean age of 52 (44.5-59.5) years. After procedure, 18 (7.3%) patients developed urinary sepsis, 10 of them (55.5%) occurred in the first 24h. The urine culture showed enterobacteria (61.1%) and enterococci (38.9%). The antibiogram showed greater sensitivity to nitrofurantoins (100%) and quinolones (72%). The statistical analysis showed that female sex, the clinical debut of urolithiasis as urinary sepsis, having received antibiotic or having required urinary diversion by a double J during debut, positive presurgical uroculture and the persistence of residual lithiasis after surgery were significantly associated (P<.05) with the development of urinary sepsis after ureterorenoscopy. CONCLUSION: Urinary sepsis is a complication that appears after performing ureterorenoscopy, especially in female patients with a history of urinary sepsis, antibiotic therapy, double J, previous positive urine culture or residual lithiasis after the procedure.

Nutrient, metal contents and microbiological properties of litter and soil along a tree age gradient in Mediterranean forest ecosystems.

The link among the age of aboveground tree species, litter, soil quality and status in Mediterranean forests is not entirely comprehended (especially in Mediterranean forest sites). This study evaluates whether and by what extent tree stand composition and forest structure modify nutrient depository or alter physical, chemical and microbiological properties of soil and litter in a 120 years old pine forest chronosequence. In general, the enzymatic activity related to the phosphorous, carbon and nitrogen cycles were more developed in litter than in soil surface, while the sulphur enzymatic activity was not significantly different between the two analyzed systems. The higher dehydrogenase content measured in the litter may be an index of a higher extracellular microbial activity, compared to soil. A noticeable effect of forest age and structure on the majority of analyzed elements was detected, with nutrients and metals tending to accumulate in soil rather in the litter. Moreover, the contents of P and some metals and sulphur enzymatic activity in the litter are influenced by forest age and associated forest structure. Finally, since nutrient, metals and enzyme contents in the litter increase with forest age, forest management strategies targeted to increase the stand structure may be advisable in order to achieve higher soil functionality.

Anti-inflammatory effect of dialysable leucocyte extract in a rat model of osteoarthritis: histopathological and molecular characterization.

OBJECTIVES: To evaluate the effect of dialysable leucocyte extract (DLE) on pro- and anti-inflammatory profiles in a rat model of osteoarthritis (OA). METHOD: Forty-eight male Wistar rats were divided into three groups: normal rats without treatment, OA rats treated with placebo, and OA rats treated with DLE. After treatment, the animals were killed to obtain cartilage for histological analysis and to determine the expression of pro- and anti-inflammatory cytokines by reverse transcription multiplex polymerase chain reaction (RT-MPCR) and immunohistofluorescence analyses. RESULTS: Histological analysis revealed that OA cartilage from rats treated with DLE displayed similar characteristics to non-OA cartilage from the control group. The OA cartilage treated with placebo showed alterations in the cellular architecture and in chondrocyte cluster formation. Analysis of cytokine expression by RT-MPCR showed that OA cartilage from DLE-treated rats expressed platelet-derived growth factor (PDGF), interferon (IFN)-γ, and fibroblast growth factor (FGF)-2, similar to non-OA cartilage from the control group. However, OA cartilage from rats treated with placebo expressed interleukin (IL)-1, PDGF, and I kappa B (IκB). Confocal immunodetection of FGF-2, PDGF, and non-phosphorylated IκB showed that they were distributed in the cytoplasm of most chondrocytes in OA cartilage from DLE-treated rats whereas no nuclear factor kappa B (NF-κB) expression was observed in the nuclei. Instead, in OA cartilage from the placebo group, only weak FGF-2 staining was observed, PDGF and IκB were not detected, and NF-κB was strongly observed in both cytoplasm and nuclei. CONCLUSIONS: Our findings suggest that DLE treatment modifies the OA process, promoting the expression of anti-inflammatory cytokines and diminishing the inflammatory effects, avoiding the nuclear translocation of NF-κB in chondrocytes.

Neumonía adquirida en la comunidad: tratamiento ambulatorio y prevención / Community acquired pneumonia in children: Outpatient treatment and prevention

La neumonía adquirida en la comunidad (NAC) en la edad pediátrica ha sufrido, en la última década, una serie de cambios epidemiológicos, clínicos, etiológicos y de resistencias a antibióticos, que obligan a replantear su abordaje terapéutico. En este documento, dos de las principales sociedades de especialidades pediátricas involucradas en el diagnóstico y tratamiento de esta entidad, como son la Sociedad Española de Infectología Pediátrica y la Sociedad Española de Neumología Pediátrica, así como el Comité Asesor de Vacunas de la AEP, proponen unas pautas consensuadas de tratamiento y prevención, con el fin de proporcionar a todos los pediatras una guía actualizada. En esta primera parte del consenso, se aborda el tratamiento de los pacientes sin enfermedades de base relevantes con NAC que no precisan ingreso hospitalario, así como la prevención global de esta patología con vacunas. En un siguiente documento se expondrá el abordaje terapéutico tanto de aquellos pacientes en situaciones especiales como de las formas complicadas de la enfermedad

There have been significant changes in community acquired pneumonia (CAP) in children in the last decade. These changes relate to epidemiology and clinical presentation. Resistance to antibiotics is also a changing issue. These all have to be considered when treating CAP. In this document, two of the main Spanish pediatric societies involved in the treatment of CAP in children, propose a consensus concerning therapeutic approach. These societies are the Spanish Society of Paediatric Infectious Diseases and the Spanish Society of Paediatric Chest Diseases. The Advisory Committee on Vaccines of the Spanish Association of Paediatrics (CAV-AEP) has also been involved in the prevention of CAP. An attempt is made to provide up-to-date guidelines to all paediatricians. The first part of the statement presents the approach to ambulatory, previously healthy children. We also review the prevention with currently available vaccines. In a next second part, special situations and complicated forms will be addressed

Effect of dietary supplementation with flaxseed oil or vitamin E on sheep experimentally infected with Fasciola hepatica.

The effects of two diets supplemented with flaxseed oil (FO) or vitamin E (VE) were studied in sheep infected with Fasciola hepatica. The control group (CO), not supplemented, had higher weight gain and faecal egg count (P < 0.05) at the end of the study. At necropsy, the number (71.2 ± 26.5) and size of flukes were lower in the FO group (P < 0.01), probably due to the higher levels of white blood cells and lymphocytes (P < 0.01). This group also had higher red blood cell and haematocrit values (P < 0.01). The CO group had more severe hypoproteinaemia and hypoalbuminaemia, due to having the highest fluke burden (123.0 ± 35.2), and also the highest IgG1 titre (P < 0.01). The diet did not affect production or gene expression levels of IFN-γ and IL-4. On the other hand, the supplementation with VE led to a reduction in adult fluke burden (97.7 ± 39.9) and lower lipid oxidation in the liver (P < 0.001).

Humoral response and colostral antibody transfer following 'one-dose' pre-mating vaccination of sows against porcine circovirus type-2.

The objective of this study was to investigate the presence of porcine circovirus type 2 (PCV2) DNA and antibody to the virus in the serum and colostrum of sows vaccinated prior to mating and in their offspring. Seventy-seven sows were randomly distributed into vaccinated (V, n=36) and non-vaccinated (NV, n=41) groups. One week before mating, sows were given a PCV2 vaccine (V group) or PBS (NV group) IM. Blood samples were taken from the sows at fixed time-points and colostrum samples were taken at farrowing. Blood samples were also taken from the piglets of the sows at 4 weeks of age. The results indicated that vaccination prior to mating elicited a strong, homogeneous humoral response and, in consequence, more homogeneous colostral PCV2 antibody concentrations.

Low-energy laser therapy for prevention of oral mucositis in hematopoietic stem cell transplantation.

AIM: To evaluate the clinical effects of laser therapy on the prevention and reduction of oral mucositis in patients who underwent hematopoietic stem cell transplantation (HSCT). PATIENTS AND METHODS: From January 2003 to September 2004, 24 patients received prophylactic laser therapy (L+ group). The applications started from the beginning of the conditioning regimen up to day +2. The oral assessment was performed daily until day +30. This group was compared with historical controls, namely 25 patients, who did not receive laser therapy (L- group). RESULTS: All patients developed some grade of mucositis. However, the L- group presented initial mucositis by 4.36 days, whereas the L+ group presented it in 6.12 days (P = 0.01). The maximum mucositis occurred between day +2 and day +6 with healing by day +25 in the L- group and between day +2 and day +7 with healing by day +14 for the L+ group (P = 0.84). Laser therapy also reduced the time of oral pain from 5.64 to 2.45 days (P = 0.04), and decreased the consumption of morphine (P = 0.07). CONCLUSION: This study suggests that laser therapy can be useful in oral mucositis to HSCT patients and improve the patient's quality of life. However, controlled randomized trials should be performed to confirm the real efficacy of laser therapy.

Estudio de los efectos de la dilución de anestésico local para técnica regional subaracnoidea en procedimientos quirúrgicos abdominales ambulatorios / Study of the effects of the dilution of local anesthesic for regional technology(skill) subaracnoidea in surgical abdominal ambulatory procedures

Este estudio fue diseñado para evaluar diferencias hemodinámicas y eventos adversos de la dilución de un anestésico local hiperbárico (clorhidrato de levobupivacaína pesada 0,75 por cien más citrato de fentanilo en solución salina normal al 0,9 por cien) comparada con la técnica estándar para anestesia regional subaracnoidea. Métodos: Estudio experimental multicéntrico, prospectivo aleatorio, abierto y controlado, en el cual fueron incluidos 98 pacientes de ambos sexos programados para procedimientos quirúrgicos abdominales; las variables analizadas fueron tensión arterial media (TAM), tiempo de bloqueo motor y sensitivo, uso de líquidos endovenosos en el acto operatorio, drogas vasoactivas y duración en la unidad de recuperación postanestésica. Resultados: Fueron evaluadas las variables para ambos grupos, encontrándose diferencias significativas en: descenso de la TAM al minuto (grupo tratado 71,96±5,99 mm Hg IC: 1,69 Vs. grupo control 58,15 ±3,70 mm Hg, IC: 1,02) con relación a la media basal inicial (76,07±6,01 Vs.76,02±6,01 mm Hg) respectivamente, posterior a la inyección del anestésico en el espacio subaracnoideo; la duración del bloqueo motor (grupo tratado 18,04 ± 7,21 minutos IC: 2,03 Vs. grupo control 89,61±23,88 minutos IC: 6,6); uso de líquidos endovenosos (grupo tratado 78,39 ± 301,24 ml IC: 22,45 Vs. grupo control 2.115 ± 339 ml IC :94,07); estancia en unidad de cuidados postanestésicos (grupo tratado 27,76±6,60 minutos IC:1,86 Vs. grupo control 105,96 ± 30,07 minutos, IC: 27,74), náuseas (grupo tratado 7 pacientes, 14,58 por cien Vs. grupo control 21 pacientes, 42 por cien), vómito (grupo tratado 5 pacientes, 10,41 por cien Vs. grupo control 16 pacientes, 32 por cien), drogas vasoactivas (grupo tratado 0 pacientes, 0 por cien Vs. grupo control 34 pacientes 68 por cien). No existió diferencia significativa en la duración del bloqueo sensitivo (grupo tratado 77±17,56 minutos, IC: 2,59 Vs. grupo control 74,80±18,24 minutos, IC: 5,05) y tiempo quirúrgico (grupo tratado 40,4±13,19 minutos, IC: 3,73 Vs. grupo control 39,42 ± 8,76 minutos, IC: 2,42). Conclusión: La dilución de anestésico local hiperbárico para técnica de anestesia regional subaracnoidea es segura, efectiva y puede recomendarse como una técnica estándar en pacientes programados para cirugía abdominal con duración máxima de una hora.

Mismatch repair status in the prediction of benefit from adjuvant fluorouracil chemotherapy in colorectal cancer.

AIM: Some retrospective studies have shown a lack of benefit of 5-fluorouracil (5-FU) adjuvant chemotherapy in patients with mismatch repair (MMR) deficient colorectal cancer. Our aim was to assess if this molecular marker can predict benefit from 5-FU adjuvant chemotherapy. A second objective was to determine if MMR status influences short term survival. METHODS: We included 754 patients with a median follow up of 728.5 days (range 1-1097). A total of 260 patients with stage II or III tumours received 5-FU adjuvant chemotherapy, according to standard clinical criteria and irrespective of their MMR status. A tumour was considered MMR deficient when either BAT-26 showed instability or there was loss of MLH1 or MSH2 protein expression. RESULTS: At the end of the follow up period, 206 patients died and 120 presented with tumour recurrence. Sixty six (8.8%) patients had MMR deficient tumours. There were no significant differences in overall survival (MMR competent 72.1%; MMR deficient 78.8%; p = 0.3) or disease free survival (MMR competent 61.3%; MMR deficient 72.3%; p = 0.08). In patients with stage II and III tumours, benefit from 5-FU adjuvant chemotherapy was restricted to patients with MMR competent tumours (overall survival: chemotherapy 87.1%; non-chemotherapy 73.5%; log rank, p = 0.00001). Patients with MMR deficient tumours did not benefit from adjuvant chemotherapy (overall survival: chemotherapy 89.5%; non-chemotherapy 82.4%; log rank, p = 0.4). CONCLUSIONS: Benefit from 5-FU adjuvant chemotherapy depends on the MMR status of tumours in patients with colorectal cancer. 5-FU adjuvant chemotherapy improves survival in patients with MMR competent tumours but this benefit from chemotherapy cannot be extended to patients with MMR deficient tumours.

Cardiovascular risk factors in vegetarians. Normalization of hyperhomocysteinemia with vitamin B(12) and reduction of platelet aggregation with n-3 fatty acids.

Hyperhomocysteinemia in association with vitamin B(12) deficiency, and increased platelet aggregation, probably due to dietary lack of n-3 fatty acids, constitute cardiovascular risk factors frequently observed in vegetarians. We tested if administration of vitamin B(12) normalizes the concentration of total plasma homocysteine, and if intake of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) fatty acids modulates platelet function in a population of lactoovovegetarians. One week after a single intramuscular injection of cyanocobalamin (10000 microg) in 18 individuals, serum vitamin B(12) increased from 149+/-63 pg/mL to 532+/-204 pg/mL (p<0.0001) and total tHcy dropped from 12.4+/-4.7 to 7.9+/-3.1 micromol/L (p<0. 0001). Ten of fourteen of these vegetarians completed an 8-week supplementation with 700 mg/day of each eicosapentaenoic and docosahexaenoic acids. Increased incorporation of these fatty acids into plasma lipids was observed in all of them, together with a significant reduction in maximum percentage or slope of platelet aggregation with all the agonists tested (ADP, epinephrin, collagen, arachidonic acid). No significant change in bleeding time was observed after n-3 fatty acid trial. Supplementation with vitamin B(12) and n-3 fatty acids corrects hyperhomocysteinemia and reduces platelet reactivity to agonists in vegetarians. Whether this supplementation improves the already reduced cardiovascular morbidity and mortality associated with vegetarian diet has yet to be demonstrated.

A high-fat diet induces and red wine counteracts endothelial dysfunction in human volunteers.

Endothelial dysfunction is associated with atherogenesis and oxidative stress in humans. In rat and rabbit blood vessels, wine polyphenol antioxidants induce vascular relaxation in vitro through the NO-cGMP pathway. To assess the effect of a regular high-fat diet (HFD) and moderate red wine consumption on endothelial function (EF), a study was performed in healthy male volunteers. EF was measured as flow-mediated dilatation of the brachial artery, employing high-resolution ultrasound after an overnight fast. Other clinical and biochemical parameters related to EF were also measured. Six volunteers received a control diet, rich in fruits and vegetables (27% calories as fat) and five volunteers received an HFD (39.5% calories as fat). Measurements were done twice on each volunteer: after a period of 30 d with diet plus 240 mL of red wine/d, and after a period of 30 d with diet, without wine. In the absence of wine, there is a reduction of EF with HFD when compared to the control diet (P = 0.014). This loss of EF is not seen when both diets are supplemented with wine for 30 d (P = 0.001). Plasma levels of n-3 fatty acids (R2 = 0.232, P = 0.023) and lycopene (R2 = 0.223, P = 0.020) show a positive correlation with individual EF measurements, but they do not account for the significant differences observed among dietary groups or after wine supplementation. These results help elucidate the deleterious effect of a high-fat diet and the protective role of wine, n-3 fatty acids and dietary antioxidants in cardiovascular disease.

Plasma polyphenols and antioxidants, oxidative DNA damage and endothelial function in a diet and wine intervention study in humans.

An intervention study was performed to evaluate the influence of a Mediterranean diet, a high fat diet, and their supplementation with red wine in moderate amounts, on biochemical, physiological, and clinical parameters related to atherosclerosis and other chronic diseases. For 3 months two groups of 21 male volunteers each, received either a Mediterranean diet or a high fat diet; during the second month, red wine was added isocalorically, 240 ml/day. Participants were kept under close medical and nutritional surveillance. At days 0, 30, 60 and 90, clinical, physiological and biochemical evaluations were made. Plasma vitamin C was significantly decreased in the high fat diet group compared to the Mediterranean diet group. After wine supplementation to the Mediterranean diet, a significant 13.5% increase in plasma vitamin C was observed. Furthermore, when wine was added vitamin E decreased significantly in plasma, 15% in the high fat diet and 26% in the Mediterranean diet. Total plasma antioxidant capacity (total antioxidant reactivity) increased 28% above basal levels in the Mediterranean diet group, but not in the high fat diet group. In both groups, wine induced a marked increase in total antioxidant reactivity above basal levels, 56% and 23%, respectively. Oxidative DNA damage, detected as 8-hydroxydeoxyguanosine (8-OHdG) levels in blood leukocyte DNA, was markedly increased by the high fat diet; however, it was strongly reduced, to approximately 50% basal values, after wine supplementation, both in the high fat diet and Mediterranean diet groups. Endothelial function, evaluated noninvasively as flow-mediated vascular reactivity of the brachial artery, was suppressed by the high fat diet, and was normal after wine supplementation. These effects are attributed to oxidative stress associated with a high fat diet, and to the elevated plasma antioxidant capacity associated with wine consumption and the Mediterranean diet. The results presented support the following conclusions: a high fat diet induces oxidative stress; a diet rich in fruits and vegetables enhances antioxidant defenses; wine supplementation to a high fat or a Mediterranean diet increases plasma antioxidant capacity, decreases oxidative DNA damage, and normalizes endothelial function.

Chimeras of alpha1-adrenergic receptor subtypes identify critical residues that modulate active state isomerization.

We have identified previously two amino acids, one in each of the fifth and sixth transmembrane segments of both the alpha1a-adrenergic receptor and the alpha1b-adrenergic receptor (AR), that account almost entirely for the selectivity of agonist binding by these receptor subtypes (Hwa, J., Graham, R. M., and Perez, D. M. (1995) J. Biol. Chem. 270, 23189-23195). Thus reversal of these two residues, from those found in the native receptor of one subtype to those in the other subtype, produces complementary changes in subtype selectivity of agonist binding. Here we show that mutating only one of these residues in either the alpha1b-AR or the alpha1a-AR to the corresponding residue in the other subtype (Ala204 --> Val for the alpha1b; Met292 --> Leu for the alpha1a-AR) results in chimeras that are constitutively active for signaling by both the phospholipase C and phospholipase A2 pathways. This is evident by an increased affinity for agonists, increased basal phospholipase C and phospholipase A2 activation, and increased agonist potency. Although mutation of the other residue involved in agonist binding selectivity, to the corresponding residue in the other subtype (Leu314 --> Met for the alpha1b-AR; Val185 --> Ala for the alpha1a-AR) does not alter receptor binding or signaling, per se, when combined with the corresponding constitutively activating mutations, the resulting chimeras, Ala204 --> Val/Leu314 --> Met ( alpha1b-AR) and Val185 --> Ala/Met292 --> Leu ( alpha1a-AR), display wild type ligand binding and signaling. A simple interpretation of these results is that the alpha1a- and alpha1b-ARs possess residues that critically modulate isomerization from the basal state, R, to the active state R*, and that the native receptor structures have evolved to select residues that repress active state isomerization. It is likely that the residues identified here modulate important interhelical interactions between the fifth and sixth transmembrane segments that inhibit or promote receptor signaling.

Digital anaesthesia through the flexor tendon sheath at the palmar level.

Sixty five patients with various traumatic lesions of the fingers have been operated on under digital anaesthesia using 3 ml of 2% Mepivacaine injected into the flexor tendon sheath. The anaesthesia was adequate for surgery in all instances except in one patient. No complications were encountered with this technique. The authors studied the mechanism of action by dissecting a cadaveric hand after injecting a tracer (Methylene blue) in place of the local anaesthesia, suggesting, but not proving, that anaesthesia is achieved by blocking the nerve in the area of the injection.

Synthesis of lactoferrin and transport of transferrin in the lactating mammary gland of sheep.

Two iron-binding proteins, lactoferrin and transferrin, are present in ruminant milk. Lactoferrin commonly has been assumed to be a product of mammary synthesis, but the origin of milk transferrin has not been elucidated. The objective of this experiment was to study the synthesis and distribution of these two proteins in the mammary gland of sheep. Explants from lactating mammary gland of sheep have been cultured in the presence of [3H]leucine to determine rates of synthesis of lactoferrin and transferrin. After incubation, [3H]lactoferrin was found, but labeled transferrin was not. The capacity of the mammary gland to synthesize lactoferrin decreased markedly in the first 24 h of lactation. Immunohistochemical techniques were utilized to identify the locations of lactoferrin and transferrin in the mammary gland. Transferrin was found in the colostrum contained in the alveolar lumen, in the cytoplasm of the secretory cells, and in the connective tissue between the mammary acini. High concentration of transferrin was found in the basal membrane of the secretory alveolar cells, mainly in those near capillary vessels. Lactoferrin was found in the colostrum and in the cytoplasm of secretory cells with a more homogeneous distribution than transferrin. The connective tissue stained negative for lactoferrin. These results suggest that, although lactoferrin is synthesized by mammary gland of the sheep, transferrin comes from blood serum, probably by a receptor-mediated mechanism of transcytosis.