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PubMed1976

Enzymic preparation of neurosecretosome- and pituicyte-enriched fractions from the rat neurohypophysis.

A microcellular dispersion procedure for the rat neurohypophysis was developed, comprising tissue softening and dissociation using a special sieving sytringe. In preparatory studies the influence of mesh width, and treatment with trypsin, pronase or collagenase-hyaluronidase was investigated using light and electron microscopy, as well as with microchemistry by means of protein and lactate dehydrogenase activity determinations. Trypsinization gave the best results. In the final adopted procedure, 3 incubated neurohypophyses were sequentially sieved through a 200- and a 50-mum mesh. The resulting 50-mul dispersion was found to contain numerous ultrastructurally well-preserved pinched-off axonal endings (neurosecretosomes), and pituicytes often revealing processes. On the basis of DNA and oxytocin assays 11% of the pituicytes and 28% of the axonal cytoplasm were recovered. Oxytocin immunofluorescence microscopy showed hormone within the neurosecretosomes, but often also in the cytoplasm of pituicytes. Microdensity gradient centrifugation was performed on neurohypophyseal disperions, in order to obtain fractions enriched for neurosecretosomes and pituicytes. Fractions were characterized by means of phase contrast, oxytocin immunofluorescence and electron microscopy, as well as by oxytocin and DNA assays as respective markers. With a 10:14:22% (w/v) Ficoll gradient, fractions were obtained for which the relative purification was by a factor of 4 on the basis of DNA/oxytocin ratios.

Animals↗
PubMed1989

The use of fluorescamine as a detection reagent in protein microcharacterization.

With recent advances in protein microchemistry, compatible methods for the preparation and quantitation of proteins and peptides are required. Fluorescamine, a reagent which reacts with primary amino groups has been used successfully to detect amino acids, peptides, and proteins in various micromethods. This article discusses these methods which include (1) amino acid analysis of protein and peptide hydrolysates with postcolumn fluorescamine derivatization; (2) purification and characterization of proteins and peptides by reversed-phase HPLC with postcolumn fluorescamine derivatization; (3) purification of peptides by two-dimensional chromatography and electrophoresis on thin-layer cellulose with fluorescamine staining; and (4) electroblotting of protein bands from SDS-PAGE to glass fiber filters and polyvinylidene difluoride (PVDF) membranes with fluorescamine staining. In addition, this article also compares a postcolumn fluorescamine detection system with a UV detection system in the applications of amino acid analysis and reversed-phase HPLC protein/peptide analysis.

Amino Acid Sequence↗
PubMed1996

Towards inexpensive DNA diagnostics.

Methodologies to obtain DNA sequence information efficiently and accurately will provide the basis for a broad spectrum of economical products and applications to a variety of industrial sectors, in addition to healthcare. Such technologies will build upon the evolving molecular biology and instrumentation base that is serving a specific research market. This will require the efficient integration of technical advances in microchemistry, micromachining, separation technologies, detection systems, microelectronics and information technology, and will involve the expertise of engineers, physicists, chemists, mathematicians, computer scientists and molecular biologists. The biotechnology, microelectronics, software, instrumentation, pharmaceutical and fine chemical industries will be vital to this development.

Animals↗
PubMedDate not supplied

An integrative hypothesis concerning the pathogenesis and progression of Alzheimer's disease.

Observations, in Alzheimer's disease, in the pattern of nerve cell damage and loss, the pathology, microchemistry and immunology of senile plaques and neurofibrillary tangles and alterations in blood vessels are drawn together into a hypothesis that attempts to explain the pathogenesis and progression of the disorder. At the heart of this hypothesis lies a defect in blood brain barrier function and/or structure within the cerebral cortex and this defect may be the cause of the cerebral vessel amyloidosis common in many patients with Alzheimer's disease. Age-related alterations in blood brain barrier allow for damage to nerve terminals and limited formation of senile plaques within cerebral cortex; neurofibrillary tangles are formed within cortical and subcortical nerve cells which project to or near damaged vessels/senile plaques. Uptake of "neurotoxin" at affected terminals and retrograde transport to perikarya causes neurofibrillary tangles to be formed; their accumulation leads to perikaryal changes culminating in cell death and loss. Loss of cells in cortically projecting areas of subcortex such as nucleus basalis, locus caeruleus and dorsal raphe, which terminate on cerebral vessels, causes further blood brain barrier dysfunction, new plaque formation and continued cell loss in cortex and subcortex. Once started, such a process could be self-perpetuating and the initial site of damage could lie within the amygdala/hippocampus with putative pathogenic agent accessing the brain via the olfactory pathways.

Age Factors↗
PubMed2001

Point-of-care testing.

Point-of-care testing technology rapidly is changing the way physicians practice medicine by facilitating the availability of biochemical parameters immediately or almost immediately. The constant evolution and developments in [figure: see text] microchemistry and computer technology will make this area a dynamic part of medicine with the constant emergence of improved and newer technologies. Clinicians must not forget, however, that the best analyzer and monitor is the physician, nurse, or other health care worker in direct contact with the patient, constantly reassessing, re-examining, and integrating all of the physiologic and biochemical data in the context of the history and physical examination. If POC testing is implemented, its goal should be to improve and assist in patient care.

Blood Transfusion↗
PubMed1997

Red cell transfusion therapy in the critical care setting.

According to our own experience and published reports the frequency of red cell transfusion in intensive care units is in the range of 0.2 to 0.4 units per patient per day and is dependent upon the local strategy, the patients involved and the kind of surgery performed. The rationale for red cell transfusion is to maintain or restore the oxygen carrying capacity of the blood to avoid tissue hypoxia which occurs when oxygen delivery drops below a certain critical value. Besides bleeding, phlebotomy is also a significant source of blood loss in critically ill patients. According to several recent reviews and consensus articles there is no basis for a fixed indicator for transfusion, such as a haemoglobin concentration of < 100 gL-1. The decision to transfuse has to be made according to the patients individual status. The major adaptive mechanism in response to acute anaemia is an increase in cardiac output and hence blood flow to tissues. As a consequence even moderate degrees of acute anaemia may not be tolerated by patients with cardiac disease, whilst marked anaemia carries a considerable risk of ischaemia in patients with brain lesions or cerebral arterial stenoses. In critically ill patients it has been postulated that supply dependency of oxygen consumption occurs over a wide range of oxygen delivery, far above the critical values of oxygen delivery seen under normal conditions. Maximising oxygen delivery was therefore formulated as a goal in these patients. However, whether pathological supply dependency of oxygen delivery really exists in critically ill patients is still under discussion and recent studies found no benefit in maximising oxygen delivery to this patient group. However, individualised triggers for red blood cell transfusion are adequate for critically ill patients considering their co-morbidities and severity of disease. Finally, the decision to transfuse must also take into account the potential risks (infectious and non-infectious), as well as benefits for the individual patient. In the future, the level of transfusions may be reduced by using blood sparing techniques such as blood withdrawal in closed systems, bedside microchemistry, intravascular monitors, or autotransfusion of drainage blood in intensive care units.

Adaptation, Physiological↗
PubMed1996

Critical care medicine: opportunities and strategies for improvement.

BACKGROUND: Like other areas of health care, critical care faces increasing pressure to improve the quality while reducing the cost of care. Strategies drawn from the literature and the authors' experiences are presented. STRATEGIES AND OPPORTUNITIES FOR IMPROVEMENTS: Ten process- or structure-related areas are targeted as strategically important focuses of improvement: (1) restructuring administrative lines to better suit key processes; (2) physician leadership in critical care units; (3) management training for critical care managers; (4) triage; (5) multidisciplinary critical care; (6) standardization of care; (7) developing alternatives to critical care units; (8) timeliness of care delivery; (9) appropriate use of critical care resources; and (10) tracking quality improvement. TIMELINESS OF CARE DELIVERY: Whatever the root cause(s) of unnecessary delays, the result is inefficient use of critical care resources-and ultimately either a need for more resources or longer wait times. Innovations designed to reduce wait times and waste, such as the establishment of a microchemistry stat laboratory, may prove valuable. APPROPRIATE USE OF CRITICAL CARE RESOURCES: Possible strategies for the appropriate use of critical care resources include better selection of well-informed patients who undergo procedures. Reduction in variation among physicians and organizations in providing therapies will also likely lead to a reduction in some high-risk procedures offering little or no benefit, and therefore a reduction in need for critical care services. Better preparation of patients and families should also make end-of-life decisions easier when questions of "futility" arise. Better information on outcomes and cost-effectiveness and consensus on withdrawal of critical care treatments represent two additional strategies.

Critical Care↗
PubMed2000

Optical detection in microscopic domains. 1. Monitoring chemical manipulations with absorption microspectrometry.

In this research, we test whether optical detection techniques, such as absorption microspectrometry, fluorescence detection, and inner filter effects, show different characteristics in microscopic domains (nano-, pico- and femtoliter range) with respect to usual solution volumes. In this part 1, characterization of absorption microspectrometry is facilitated by the use of a novel microscopic tool, the diffusional microburet (DMB), suitable for fine chemical manipulations of microscopic liquid samples. Since diffusional delivery of substances will not induce appreciable changes in volume and shape of the sample, a DMB makes it possible to obtain spectral recordings and a reference spectrum from the same microscopic droplet. Thus, good quantitative spectra of microscopic domains can be assessed. With this approach, despite the curvature of the sample boundaries, the large surface-to-volume ratios, and microscopic optical path lengths, both Beer-Lambert's law and the law of superposition were found to be directly applicable in microscopic domains without any corrections for absorption at sample boundaries. Use of a combination of microspectrometry and chemical manipulations by DMBs made it possible for the first time to record in real time, in truly microscopic domains, spectral evolution upon addition or subtraction of chemicals, as well as monitor the progress of chemical reactions. This approach is expected to contribute to the optical exploration of microchemistry and microanalysis.

Optics and Photonics↗
PubMed2003

Recognizing and interpreting the fossils of early eukaryotes.

Using molecular sequence data, biologists can generate hypotheses of protistan phylogeny and divergence times. Fossils, however, provide our only direct constraints on the timing and environmental context of early eukaryotic diversification. For this reason, recognition of eukaryotic fossils in Proterozoic rocks is key to the integration of geological and comparative biological perspectives on protistan evolution. Microfossils preserved in shales of the ca. 1500 Ma Roper Group, northern Australia, display characters that ally them to the Eucarya, but, at present, attribution to any particular protistan clade is uncertain. Continuing research on wall ultrastructure and microchemistry promises new insights into the nature and systematic relationships of early eukaryotic fossils.

Animals↗
PubMedDate not supplied

Striped iron zoning of olivine induced by dislocation creep in deformed peridotites.

Deformation of solid materials affects not only their microstructures, but also their microchemistries. Although chemical unmixing of initially homogeneous multicomponent solids is known to occur during deformation by diffusion creep, there has been no report on their chemical zoning due to deformation by dislocation creep, in either natural samples or laboratory experiments. Here we report striped iron zoning of olivine ((Mg,Fe)2SiO4) in deformed peridotites, where the iron concentration increases at subgrain boundaries composed of edge dislocations. We infer that this zoning is probably formed by alignment of edge dislocations dragging a so-called Cottrell 'atmosphere' of solute atoms (iron in this case) into subgrain boundaries during deformation of the olivine by dislocation creep. We have found that the iron zoning does not develop in laboratory experiments of high strain rates where dislocations move too fast to drag the Cottrell atmosphere. This phenomenon might have important implications for the generation of deep-focus earthquakes, as transformation of olivine to high-pressure phases preferentially occurs in high-iron regions, and therefore along subgrain boundaries which would be preferentially aligned in plastically deformed mantle peridotites.

Journal Article↗
PubMed1978

Acidosis and growth in nonuremic renal disease.

Our data demonstrate that correction of acidosis is sustained in children with type 1 RTA when alkali therapy is given in doses of 5 to 14 mEq/kg/day. The large doses are required as a result of renal bicarbonate-wasting. Children with type 1 RTA and acidosis who have significant growth impairment experience catch-up growth and attain normal stature for their age when correction of acidosis is sustained. Whether chronic acidosis impairs growth in any clinical condition except type 1 RTA is not settled. Whether sustained correction of acidosis with alkali therapy will allow attainment of normal stature in children with nonuremic diffuse renal disease is not yet determined. With the increasing availability of microchemistry and microgasometry and the new standards for growth based on mean-parent height [40], it can be anticipated that answers to these clinically important questions will be forthcoming.

Acidosis↗
PubMed2001

Reversible inhibition of spermatogenesis in rats using a new male contraceptive, 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide.

The oral male contraceptive agent 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF2364) is a new analogue of indazole-carboxylic acid. AF2364 was orally administered to rats at 50 mg/kg body weight once weekly for five consecutive weeks. The effects on fertility efficacy, hormonal profile, organ weights, tissue morphology, and serum microchemistry were examined. Complete infertility was noted in rats 29 days after the initial dose of AF2364 and continued until 90 days. Fertility resumed in 25% of the group after 104 days and had resumed in 75% of the rats by the last mating at 197 days. Morphological examination of the testis showed rapid exfoliation of elongated spermatids and the generation of large multinucleated cells 6 days after the first treatment, with depletion of most germ cells after 40 days. Normal spermatogenesis was noted in 95% of the tubules in the animals that were fertile at 210 days. Morphological analysis of the epididymal compartments revealed reduced lumen size, whereas the prostate exhibited an increase in the glandular lumen with a reduction in epithelium height. No morphological changes were detected in the kidney, liver, and cerebrum by light microscopy. Kidney and liver function, as evaluated by serum chemistry, were not affected by the drug treatment. AF2364 did not alter the levels of FSH, and only minimal changes were noted for LH and testosterone, suggesting that the hypothalamic-pituitary-testicular axis was not affected. These results illustrate the potential of AF2364 as a male contraceptive.

Animals↗
PubMed2001

Two new male contraceptives exert their effects by depleting germ cells prematurely from the testis.

The three currently available male contraceptive approaches are 1) the barrier method such as the condom, 2) hormonal methods by disrupting the pituitary-testicular axis so as to impair spermatogenesis, and 3) immunological methods by preparing vaccines against male-specific antigens. We hereby describe an alternative approach in which attachments of developing germ cells onto the seminiferous epithelium are disrupted, thereby inducing their premature release into the tubular lumen. This in turn leads to infertility. A panel of analogues based on the core structure of 1-(2,4-dichlorobenzyl)-indazole-3-carboxylic acid was synthesized. These compounds were subjected to an in vivo screening assay assessing their effects in inducing the expression of testin, a testicular marker whose expression correlates with the integrity of Sertoli-germ cell junctions. An induction of testin expression in the testis signifies a disruption of Sertoli-germ cell junctions that is followed by depletion of germ cells from the seminiferous epithelium. Two compounds, namely 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF-2364) and 1-(2,4-dichlorobenzyl)-indazole-3-acrylic acid (AF-2785), were identified that caused detachment of germ cells, in particular round and elongated spermatids, from the epithelium inducing their premature release into the tubular lumen as confirmed by histological analysis. Adult rats receiving several oral doses of either one of these compounds became infertile within 3-7 wk after the epididymal sperm reserve was exhausted. Depending on the dosing of the administered compound, rats became infertile for 4-14 wk before their fertility gradually bounced back, illustrating the reversibility and efficacy of these new compounds. Also, these compounds did not appear to impair the hypothalamus-pituitary-testicular axis because the serum levels of LH, FSH, and testosterone of the treated animals did not change significantly when compared to control rats. In addition, results of serum microchemistry illustrate that liver and kidney function was not affected in animals treated with both compounds.

Animals↗
PubMed1999

Chemical composition of saccular endolymph and otolith in fish inner ear: lack of spatial uniformity.

Fish otoliths provide a record of age, growth, and environmental influences. In both trout and turbot, spatial chemical investigation of the endolymph surrounding the otolith (sagitta) showed a lack of uniformity. Proteins, PO(3-)(4), and Mg(2+) were significantly more concentrated in the proximal (facing the macula) than distal zone, whereas the opposite was observed for K(+) and total CO(2) (totCO(2)). Na(+) concentration ([Na(+)]) was 20% higher in the proximal zone in trout but not in turbot. Total Ca and Cl(-) contents were uniformly distributed in both species. We propose that the endolymphatic gradients of protein and totCO(2) concentration within the endolymph are involved in the otolithic biocalcification process. Microchemical analyses of otolith sections by wavelength dispersive spectrometry showed a lack of spatial uniformity in the K/Ca and Na/Ca ratios, whereas the Sr/Ca ratio was uniform. There is a clear relationship between endolymph and otolith [K(+)], but the interpretation of the results for [Na(+)] needs further investigation. Thus the lack of uniformity in the otolith composition must be taken into account when investigating otolith microchemistry.

Animals↗
PubMed1980

Analysis of urinary calculi in adults. Attempt of correlations between morphology and composition.

The analysis of 322 urinary calculi in adults by microdissection, infrared spectromorphometry and microchemistry has shown that stones could be classified in several groups according to their morphology and composition: 8 morphological types have been defined (2 for the oxalic, 2 for the uric, 2 for the phosphatic and 2 for the cystinic stones). Correlations between morphology and composition have been established dividing the calculi into 10 categories, 4 for the pure forms and 6 for the mixed forms; the total includes approximately 94% of the calculi analyzed. An 11th category gathering various lithiases (rare or with multiple components) represents 6% of the cases. Moreover, the study of the localization of the component in stones emphasizes the high frequency of Ca phosphates in the nucleus of oxalic lithiases: 80% in mixed forms, in which the oxalate is the main constituent.

Adult↗
PubMed2001

Oviductin (Muc9) is expressed in rabbit endocervix.

While isolating and characterizing cervical mucin glycoproteins, oviductin (Muc9) was identified in the rabbit endocervix. Following tissue homogenization, endocervical proteins were fractionated by exclusion chromatography (Sepharose CL-4B). High molecular weight components of the void volume were resolved by density gradient centrifugation using cesium bromide and dissociative conditions (4 M guanidinium chloride). High density fractions (rho = 1.40 - 1.56 g/ml) were deglycosylated with anhydrous trifluoromethane sulfonic acid and sent to Harvard Microchemistry where in situ digestion and tryptic peptide separation were performed. Out of an HPLC map, microsequence (KLIMGFPTYGR) from peak 51 was 100% identical to mouse oviductin, and microsequence (KSTGHNFPLP) from peak 70 was 90% identical to hamster oviductin. Temporal expression of oviductin transcripts (2.4-kilobase) was negligible during the first three months of postnatal cervical differentiation. Transcripts were minimally detectable in the cervices of 4-month-old juveniles. Strong expression in the endocervices of adults was eliminated by ovariectomy and restored by estrogen treatment. The presence of oviductin in the rabbit endocervix indicates this glycoprotein may have multiple functions, and it can no longer be considered oviduct-specific.

Animals↗
PubMed1999

The laboratory-clinical interface: point-of-care testing.

POC testing provides an opportunity for clinicians and laboratorians to work together to consider how best to serve the patients within an individual institution. Each health system has unique characteristics relative to patient population, as well as a unique laboratory structure. If physicians, nurses, laboratorians, and pathologists work collaboratively, the best interests of patients will be served. In some institutions that cater to specific patient groups, POC testing may offer clear and distinct advantages. In other institutions with sophisticated transport systems and established rapid response capabilities, the quality resulting from central laboratory testing may outweigh any advantages of bedside testing. Clearly, attention to regulatory issues, QC issues, the importance of proper documentation, proficiency testing, performance enhancement, and cost-effectiveness is requisite. As the technology for diagnostic testing advances through more microcomputerization, microchemistry, and enhanced test menus, the concept of POC testing will need perpetual revisiting. We hope that the information provided here will aid clinicians, laboratorians, and administrators in their quest to best serve their patients.

Costs and Cost Analysis↗
PubMed2004

Biomaterials, biomechanics, tissue healing, and immediate-function dental implants.

Selected factors and opinions are reviewed specific to immediate function of dental implants in terms of biomaterial and biomechanical properties and how they might influence postsurgical tissue healing. Comparisons are made among plate, rod, and screw vs plateau, finn, and porous geometry endosteal dental-implant designs with and without alterations in device body-surface microchemistry and microtopography. Available information introduces more questions than answers, and recommendations are made for ongoing studies of bone responses specific to the implant fit and fill parameters focused on the kinetics of postsurgical osteotomy healing and applied loading. The clinical literature supports opportunities for immediate function; however, proposals about pathways for bone healing need further investigation. The current trends within the discipline of implant dentistry offer opportunities to reevaluate current vs previous immediate-function systems.

Biocompatible Materials↗