Interprotein metal ion exchange between cadmium-carbonic anhydrase and apo- or zinc-metallothionein

The ligand substitution reactions of cadmium-carbonic anhydrase with EDTA and pyridine-2,6-dicarboxylic acid were compared with one in which rabbit apometallothionein was the competing metal-binding agent. This last reaction occurred more rapidly than the other two at a much smaller ratio of competing ligand to Cd-carbonic anhydrase. It was characterized as a second-order reaction, first-order in Cd-carbonic anhydrase and in apometallothionein, having a rate constant of 5.8 +/- 0.1 M-1 s-1 at 25 degrees C and pH 7.4 in Tris.HCl buffer and 0.1 M KCl. At 25 degrees C, Zn7-metallothionein also exchanged metal ions with Cd-carbonic anhydrase with a rate constant of 0.33 +/- 0.02 M-1 s-1 to reconstitute enzymatically active protein. Cd-carbonic anhydrase reacted within the time of mixing with the peptide sequence 49-61 of rabbit metallothionein 2 which contains four cysteinyl residues, leading to the exchange of most of the Cd2+ into the peptide. At pH 7.4 and 25 degrees C, Cd2+ has higher affinity for apometallothionein than for the apo-peptide.

Defining the burden of pneumonia in children preventable by vaccination against Haemophilus influenzae type b

OBJECTIVES

To determine the burden of pneumonia requiring hospitalization in infants and young children preventable by vaccination against Haemophilus influenzae type b (Hib).

DESIGN

Vaccination centers in Santiago, Chile, were randomly selected to administer PRP-T, an Hib conjugate vaccine, combined with diphtheria-tetanus toxoids-pertussis (DTP) vaccine or DTP alone.

SUBJECTS

Infants who received > or =2 doses of DTP or DTP and Hib conjugate vaccine combined.

MAIN OUTCOME MEASURES

Pneumonia episodes leading to hospitalization accompanied by indicators of likely bacterial infection including radiologic evidence of alveolar consolidation or pleural effusion, an elevated erythrocyte sedimentation rate (> or =40 mm/h) or bronchial breath sounds on auscultation.

RESULTS

In participants age 4 to 23 months, PRP-T reduced the incidence of pneumonia associated with alveolar consolidation or pleural effusion by 22% (95% confidence interval, -7 to 43) from 5.0 to 3.9 episodes per 1000 children per year. When the pneumonia case definition included any of the following, alveolar consolidation, pleural effusion, erythrocyte sedimentation rate > or =40 mm/h or bronchial breath sounds, PRP-T provided 26% protection (95% confidence interval, 7 to 44) and prevented 2.5 episodes per 1000 children per year.

CONCLUSIONS

Hib vaccine provides substantial protection against nonbacteremic pneumonia, particularly those cases with alveolar consolidation, pleural effusion or other signs of likely bacterial infection. Hib vaccination prevented approximately 5 times as many nonbacteremic pneumonia cases in infants as meningitis cases, thus indicating that the largest part of the effect of Hib vaccination might be undetectable by routine culture methods.

Synthetic PMMA-grafted polysaccharides as hydrophilic matrix for controlled-release forms

This paper describes the rheological behavior of starch and cellulose acrylic graft copolymers synthesized with the aim of obtaining controlled-release excipients. The rheological characteristics determine the final release properties of matrix tablets. The study of the storage and loss moduli (G' and G", respectively) and the viscosity allowed us to know if the polymer behavior was that of a gel and, hence, if it could act as a barrier to drug diffusion. Since dynamic measurements showed a storage modulus higher than the loss modulus, we assessed that all the polymers were gels. Thus, knowing that all the graft copolymers had acceptable properties for compression, the release of theophylline as a model drug at different pH was studied. Polymers with higher absorption capacity, viscosity, and compactibility allowed formulations with slower release rates.

The usefulness of Tc-99m tetrofosmin scintigraphy in the diagnosis and localization of hyperfunctioning parathyroid glands

PURPOSE

The aim of the work was to study the diagnostic value of Tc-99m tetrofosmin to localize anomalous parathyroid glands in patients with hyperparathyroid disease.

METHODS

We studied 31 patients, 19 with primary and 12 with secondary hyperparathyroid disease. Five of these patients were renal graft recipients. All patients underwent surgery. Each patient was injected with 555 to 740 MBq (15 to 20 mCi) Tc-99m tetrofosmin. Subsequently, radionuclide images were acquired 15 and 120 minutes after injection using a low-energy, all-purpose, parallel-hole collimator. Pertechnetate thyroid scintigraphy was obtained in nine cases (24 to 48 h later) when the thyroid activity made it difficult to identify the parathyroid glands.

RESULTS

All cases showed tracer uptake as early as 15 minutes after injection. In the group of patients with primary hyperparathyroid disease, 15 showed focal uptake in a parathyroid gland, and surgery revealed an adenoma in the same location. In one patient with hyperplasia, scintigraphy identified only two of four diseased glands. In the three remaining cases, scintigraphy showed focal uptake in the lower parathyroid gland, whereas at surgery the abnormal gland was located in the upper pole. In the secondary hyperparathyroidism group, seven patients showed diffuse tracer uptake in two or more glands, and histologic analysis confirmed hyperplasia in all of them. Five cases showed focal uptake, with three evaluated after surgery (uptake in the only remaining gland); one of them was a renal graft recipient, and the remaining patient had chronic renal failure and was receiving hemodialysis.

CONCLUSIONS

Our results suggest that Tc-99m tetrofosmin may be a suitable tracer for preoperative detection and screening of anomalous parathyroid glands. The earlier images at 15 minutes were better than those at 120 minutes. Tc-99m tetrofosmin is cleared more slowly from the normal thyroid than is Tc-99m sestamibi, and both of these tracers may give better results than the old pertechnetate TI-201 subtraction technique.

Mitochondrial diseases in children: neuroradiological and clinical features in 17 patients

Mitochondrial diseases result from structural, biochemical or genetic defects of mitochondria, which contain the respiratory chain. They usually affect children and young adults. We report the CT and MRI findings in 17 patients under 14 years of age, the youngest reported to date, with various mitochondrial diseases. Although imaging studies may be normal negative in the early stages, follow-up usually shows many abnormalities, which depend on clinical status and the disease. We have recognised a spectrum of findings that can be divided into four patterns: nonspecific myelin lesions (8/17); grey-matter nuclei involvement (6/17); a leukodystrophic pattern; and calcification of the brain (1/17), although mixed forms, particularly myelin and grey-matter lesions are frequent.

Identification of a mammalian homologue of the fungal Tom70 mitochondrial precursor protein import receptor as a thyroid hormone-regulated gene in specific brain regions

Thyroid hormone is an important regulator of mammalian brain maturation. By differential display PCR, we isolated a cDNA clone (S2) that is specifically up-regulated in the striatum of neonatal hypothyroid rats. S2 was identified as KIAA0719, the first human gene distantly homologous to the fungal Tom70, which encodes a member of the translocase mitochondrial outer membrane complex involved in the import of preproteins into the mitochondria. By northern and in situ hybridization studies, KIAA0719 was found to be up-regulated in the striatum, nucleus accumbens, and discrete cortical layers of 15-day-old hypothyroid rats. In contrast, lower expression was found in the olfactory tubercle, whereas no differences were detected in other brain regions. Significantly, treatment of hypothyroid animals with single injections of thyroxine restored the normal levels of KIAA0719 expression. Moreover, treatment of control animals with thyroxine led to a reduced expression, demonstrating a negative hormonal regulation in vivo. Thus, KIAA0719 gene expression is regulated by thyroid hormone in the neonatal rat brain in a region-specific fashion. Given the role of the homologous Tom70 gene, the alteration of KIAA0719 expression may contribute to the changes in mitochondrial morphology and physiology caused by hypothyroidism in the developing rat brain.

A postmarketing surveillance program to monitor Ultram (tramadol hydrochloride) abuse in the United States

Tramadol HCl, marketed as Ultram in the USA, was introduced as a non-scheduled drug in April 1995 based on the assumption that the risk of abuse was sufficiently low to warrant a non-scheduled status. However, approval was contingent upon the development of an innovative proactive surveillance program, to be overseen by an independent steering committee, which would detect unexpectedly high levels of abuse. The postmarketing surveillance program consisted of systematic collection and scientific evaluation of reports of suspected abuse in high-risk populations surveyed through an extensive key informant network of drug abuse specialists and all spontaneous reports of abuse received through the FDA MedWatch system. Methods to estimate the number of patients prescribed tramadol were also developed. Monthly rates of abuse were calculated as an index of the risk-benefit ratio (i.e., abuse cases per 100,000 patients prescribed the drug). The data for the 3 years since the drug was introduced show that the reported rate of abuse has been low. Although a period of experimentation seemed to occur in the first 18 months after its introduction--which reached a peak rate of approximately two cases per 100,000 patients exposed--during the 2 year period prior to June 1998, the reported rate of abuse has significantly (P = 0.011) declined, reaching levels of less than one case per 100,000 patients in the last 18 months. The overwhelming majority of abuse cases (97%) have been found to occur among individuals with a history of substance abuse and the abuse has been confined to isolated pockets around the country-notably none of which have significant populations of street drug abusers. Thus, the data support the decision not to schedule tramadol and, furthermore, suggest that a proactive post-marketing surveillance program can be successfully developed to effectively monitor abuse of new medications.

Pharmacokinetics of the somatostatin analog lanreotide in patients with severe chronic renal insufficiency

OBJECTIVE

To characterize the pharmacokinetic profile of the somatostatin analog lanreotide in patients with severe chronic renal insufficiency.

METHODS

Lanreotide was administered by intravenous bolus (7 microg/kg) to 12 patients with severe chronic renal insufficiency and to 12 healthy subjects. Lanreotide serum levels were determined by a radioimmunoassay procedure from time 0 until 24 hours after the administration. The main pharmacokinetic parameters were estimated by a noncompartmental treatment of data.

RESULTS

The total serum clearance of lanreotide was found to be significantly lower in patients with severe chronic renal insufficiency than in healthy subjects (mean +/- SEM values of 0.138 +/- 0.017 L/hr/kg versus 0.244 +/- 0.027 L/hr/kg; P < .005). The initial lanreotide concentration, the elimination half-life, the area under the curve from time zero to 24 hours, and the area under the curve from time zero to infinity were significantly greater in patients with severe chronic renal insufficiency than in healthy subjects (307.45 +/- 79.19 ng/mL versus 127.18 +/- 22.65 ng/mL [P < .05]; 2.39 +/- 0.33 hours versus 1.32 +/- 0.20 hours [P < .005]; 62.55 +/- 9.73 ng/mL x hr versus 32.09 +/- 3.23 ng/mL x hr [P < .005]; and 62.95 +/- 9.78 ng/mL x hr versus 32.30 +/- 3.23 ng/mL x hr [P < .005], respectively). The initial volume of distribution, but not the volume of distribution at steady state, was significantly lower in patients with severe chronic renal insufficiency (0.040 +/- 0.008 L/kg versus 0.092 +/- 0.020 L/kg [P < .05] and 0.110 +/- 0.018 L/kg versus 0.172 +/- 0.046 L/kg [difference not statistically significant], respectively). The mean residence time was similar in both groups (0.77 +/- 0.06 hours versus 0.65 +/- 0.14 hours [difference not statistically significant]).

CONCLUSIONS

A reduction in the total serum clearance and a decrease in the initial volume of distribution of lanreotide were observed in patients with severe chronic renal insufficiency treated with one intravenous bolus dose of 7 microg/kg lanreotide.

Retinoic acid and 1,25-dihydroxyvitamin D3 inhibit tenascin-C expression in rat glioma C6 cells

Tenascin-C (Tn-C) is an extracellular matrix protein with growth-, invasive-, and angiogenesis-promoting activities. Tn-C is upregulated during wound healing, tumorigenesis, and other pathological conditions. Highly malignant gliomas with poor prognosis exhibit high levels of Tn-C expression. Here we demonstrate that Tn-C RNA expression in glioma C6 cells is inhibited in a dose-dependent manner by retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (1,25-D3). No additive or synergistic effects were found. Inhibition is maximum 24 hr after RA or 1,25-D3 treatment, prior to a delayed cytotoxic effect starting at day 4-5 of treatment, and correlates with a reduction in the synthesis of Tn-C protein. Tn-C expression is also inhibited, but to a lesser extent by prostaglandin D2 (PGD2). Furthermore, both RA and 1,25-D3, but not PGD2 abolish the induction of Tn-C by the tumor promoter 12-O-tetradecanoyl phorbol 13-acetate. The inhibition of Tn-C expression might be relevant for the anti-cancer activity of RA and 1,25-D3.

Oxygen therapy during exacerbations of chronic obstructive pulmonary disease

Venturi masks (VMs) and nasal prongs (NPs) are widely used to treat acute respiratory failure (ARF) in chronic obstructive pulmonary disease (COPD). In this study, these devices were compared in terms of their potentiality to worsen respiratory acidosis and their capacity to maintain adequate (> 90%) arterial oxygenation (Sa,O2) through time (approximately 24 h). In a randomized cross-over study, 18 consecutive COPD patients who required hospitalization because of ARF were studied. After determining baseline arterial blood gas levels (on room air), patients were randomized to receive oxygen therapy through a VM or NPs at the lowest possible inspiratory oxygen fraction that resulted in an initial Sa,O2 of > or = 90%. Arterial blood gas levels were measured again 30 min later (on O2), and Sa,O2 recorded using a computer during the subsequent approximately 24 h. Patients were then crossed-over to receive O2 therapy by means of the alternative device (NPs or VM), and the same measurements obtained again in the same order. It was observed that both the VM and NPs improved arterial oxygen tension (p<0.0001) to the same extent (p=NS), without any significant effect upon arterial carbon dioxide tension or pH. However, despite this adequate initial oxygenation, Sa,O2 was < 90% for 3.7+/-3.8 h using the VM and for 5.4+/-5.9 h using NPs (p<0.05). Regression analysis showed that the degree of arterial hypoxaemia (p<0.05) and arterial hypercapnia (p<0.05) present before starting O2 therapy and, particularly, the initial Sa,O2 achieved after initiation of O2 therapy (p<0.0001) enabled the time (in h) that patients would be poorly oxygenated (Sa,O2 < 90%) on follow-up to be predicted. These findings suggest that, in order to maintain an adequate (> 90%) level of arterial oxygenation in patients with chronic obstructive pulmonary disease and moderate acute respiratory failure: 1) the initial arterial oxygen saturation on oxygen should be maximized whenever possible by increasing the inspiratory oxygen fraction; 2) this strategy seems feasible because neither the VM nor NPs worsen respiratory acidosis significantly; and 3) the Venturi mask (better than nasal prongs) should be recommended.

Locomotor response to exercise in relation to plasma lactate accumulation and heart rate in Andalusian and Anglo-Arabian horses

To establish the effect of the locomotor pattern on heart rate (HR) and plasma lactate (LA), 28 horses, 18 Andalusian (AN) and 10 Anglo-Arabian (AA), aged 3-4 years, were studied. After a warm-up period, the horses performed a four-step test at 5, 6, 7 and 8 m/s, covering 1000 m at each velocity. HR was monitored, LA was analysed at rest and after each workload, and images were filmed. The locomotor parameters determined were stride duration (SD), frequency (SF) and length (SL), step and bipedal support durations, stance (restraint and propulsion) and swing phase durations, and stride vertical component. The HR and LA were significantly higher in the AN horses from velocities of 5 m/s. Similarly, the stride vertical component was higher in the AN horses at the trot and in the leading forelimbs at the gallop. Conversely, at all the galloping velocities, swing phase duration and stride length were longer in the AA horses. Significant correlations between HR, LA and locomotor pattern were only found in the AN horses. It was concluded that the greater stride vertical component in the AN horses limits SL and the cranial advancement of the hoof, with the result that reaching a longer SL triggers an increase in HR and LA. AA horses reach a balance between SL and SF, improving the efficiency of the gait.

The human cranial remains from Gran Dolina Lower Pleistocene site (Sierra de Atapuerca, Spain)

In this article we study the cranial remains of the late Lower Pleistocene human fossils from Gran Dolina (Sierra de Atapuerca, Spain), assigned to the new species Homo antecessor. The cranial remains belong to at least five individuals, both juveniles and adults. The most outstanding feature is the totally modern human morphology of the very complete face ATD6-69, representing the earliest occurrence of the modern face in the fossil record. The Gran Dolina fossils show in the face a suite of modern human apomorphies not found in earlier hominids nor in contemporary or earlier Homo erectus fossils. There are also traits in the Gran Dolina fossils shared with both Neandertals and modern humans, which reinforce the hypothesis that Neandertals and modern humans form a clade, and that the Gran Dolina fossils are a common ancestor to both lineages.

Determination of the glass transition temperatures of some new methyl methacrylate copolymers using modulated temperature differential scanning calorimetry (MTDSC)

PURPOSE

The purpose of this study was to determine the glass transition temperatures of new graft copolymers using Modulated Temperature Differential Scanning Calorimetry (MTDSC), and to assess the differences between starch and cellulosic derivatives of methyl methacrylate and between two different drying methods used in their preparation.

METHODS

Graft copolymers of methyl methacrylate were synthesized and dried by oven or freeze-drying. Surface area measurements and different thermal analysis techniques (Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and MTDSC) were used to characterize these copolymers. Results. DSC was not sensitive enough to identify the T(g)s of the copolymers, however they were clearly identifiable by MTDSC. T(g) values obtained may depend on the method of preparation that also altered their physical characteristics e.g. specific surface area. Cellulose derivatives showed lower T(g)s than starch derivatives. The results also depended on the drying method used, thus, freeze dried products had slightly lower T(g)s than oven dried products.

CONCLUSIONS

MTDSC represents a useful thermal technique that allows the identification of glass transitions in these new copolymers with higher sensitivity and resolution than conventional DSC, separating the transition from overlapping phenomena such as decomposition or dehydration. The Tg of this new class of copolymers appeared to be dependent on polymer composition and drying method used.

Structural and ultrastructural study of GH, PRL and SMT cells in male goat by immunocytochemical methods

The structural and ultrastructural characteristics of adenohypophyseal growth hormone (GH)-, prolactin (PRL)- and GH-PRL (SMT)-secreting cells were studied using immunocytochemical techniques in two normal and one lactating male goat. SMT cells were found in both types of males, which showed the same characteristics as those reported for the female. PRL and SMT cells were more frequent in the lactating male, which reflects their greater galactopoietic activity. GH cells did not seem to influence this process significantly.