Ionic Fragmentation of the Halothane Molecule Induced by EUV and Soft X-ray Radiation.

EUV and soft X-ray-induced photofragmentation of the halothane (CF3CHBrCl) molecule has been investigated using time-of-flight mass spectrometry in the coincidence mode (PEPICO) covering the valence region and vicinity of the bromine 3d, chlorine 2p, and carbon 1s edges. Total and partial ion yields have been recorded as a function of photon energy. At lower photon energies, the heavier singly charged molecular fragments predominate in the mass spectra. On the other hand, there is a strong tendency to the atomization of the molecule at higher photon energies. Despite the different chemical environments experienced by the two carbon atoms, weak site-specific fragmentation is observed. In addition, ab initio quantum mechanical calculations at the MP2 level and a series of computations with multiconfigurational self-consistent field have been performed to describe the inner-shell states.

Competition between the shake-off and knockout mechanisms in the double and triple photoionization of the halothane molecule (C2HBrClF3).

The ratios of single, double, and triple ionizations to the total photoionization of the halothane (C2HBrClF3) molecule have been investigated by a single-photon ionization in the energy range from 21.21 eV to 320 eV. In the valence region, the multiple ionization results can be described by a sum of contributions generated from the shake-off and the two-step one models. At low photon energies (from the threshold of triple ionization up to 100 eV), the triple photoionization dynamics of halothane can be reasonably well described by a model involving a classical electron impact double ionization of the singly ionized parent ion.

Anion replacement at Au(110)/electrolyte interfaces.

A characteristic reflection anisotropy spectrum (RAS) is observed from a Au(110) surface in a wide range of electrolytes and combinations of pH and applied potentials. It is suggested that this common RAS profile arises from an interaction between the potential applied to the Au(110) electrode and the dipole moments of oxidized species that locates the Fermi level at a common position with respect to the electronic band structure of Au. Rapid changes in this RAS profile are observed for Au(110)/H2SO4 as the potential is switched between 0.3 V and 0.6 V, a potential range in which the surface is not reconstructed and below the potential range of surface oxidation. The spectral changes are completed in less than 10 ms, are reversible and are attributed to the replacement of adsorbed anions by an oxygenated species.

The stability of the Au(1 1 0)-(1 × 3) surface reconstruction in electrochemical environments.

Changes in the reflection anisotropy (RAS) profile of the Au(1 1 0)-(1 × 3)/Na2SO4 interface over 25 h are attributed to the slow accumulation of impurities on the Au(1 1 0) surface which reduce the intensity of a transition involving a surface state that makes a positive contribution to the RAS profile at 1.8 eV. The growth in the intensity of a feature that makes a negative contribution to the RAS profile at 2.6 eV and the reduction in the intensity of contributions to higher energy is attributed to shifts in the energy of the surface band structure relative to the Fermi level caused by the accumulation of impurities. There is no clear explanation of the subsequent decay of the 2.6 eV feature or the long term reduction in intensity to high energy of the RAS profile.

Concerns and expectations in patients presenting with physical complaints. Frequency, physician perceptions and actions, and 2-week outcome.

BACKGROUND: Specific concerns and expectations may be a key reason that people with common physical complaints seek health care for their symptoms. OBJECTIVES: To determine the frequency of symptom-related patient concerns and expectations, physician perceptions and actions, and the relationship of these factors to patient satisfaction and symptom outcome. METHODS: This was a prospective cohort study of 328 adult outpatients presenting for evaluation of a physical complaint. The setting was a general medicine clinic in a teaching hospital. Measures included previsit patient questionnaire to identify symptom-related concerns and expectations; a postvisit physician questionnaire to determine physician perceptions and actions; and a 2-week follow-up patient questionnaire to assess symptom outcome and satisfaction with care. RESULTS: Pain of some type accounted for 55% of common symptoms, upper respiratory tract illnesses for 22%, and other physical complaints for 23%. Two thirds of patients were worried their symptom might represent a serious illness, 62% reported impairment in their usual activities, and 78%, 46%, and 41% hoped the physician would prescribe a medication, order a test, or provide a referral. Physicians often perceived symptoms as less serious or disabling and frequently did not order anticipated tests or referrals. While symptoms improved 78% of the time at 2-week follow-up, only 56% of patients were fully satisfied. Residual concerns and expectations were the strongest correlates of patient satisfaction. CONCLUSIONS: Improved recognition of symptom-related concerns and expectations might improve satisfaction with care in patients presenting with common physical complaints.

The reflection anisotropy spectroscopy of the Au(1 1 0) surface structures in liquid environments.

The reflection anisotropy (RAS) profiles of the Au(1 1 0)-(1 × 1), (1 × 2) and (1 × 3) surface structures in electrochemical environments are shown to arise mainly from surface dipole transitions directed along the principal axes of the Au(1 1 0) surface. There are weak contributions to the RAS profiles of the Au(1 1 0)-(1 × 1) and (1 × 3) surfaces in the region of 4.0 eV which probably arise from (1 1 1) facets that are either intrinsic to the surface structures or are associated with steps. A transition involving a surface state just above the Fermi level, E F, contributes to the RAS profiles of the (1 × 2) and (1 × 3) surfaces but not to the RAS profile of the (1 × 1) surface. A strong feature at 2.5 eV in the RAS profiles of the Au(1 1 0)-(1 × 1) and (1 × 2) surfaces is attributed to a transition in the vicinity of the L point of the Brillouin zone between the 5d band and the [Formula: see text] band at E F. It is argued that the applied potential of -0.6 V, which creates the Au(1 1 0)-(1 × 3) surface, lifts E F above the [Formula: see text] band causing it to become occupied and quenching this contribution to the RAS profile.

Simultaneous dynamic electrical and structural measurements of functional materials.

A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli.

Glucose stimulates the biosynthesis of rat I and II insulin to an equal extent in isolated pancreatic islets.

The effects of glucose on insulin biosynthesis were studied by measuring the incorporation of radiolabelled amino acids into proinsulin/insulin in isolated rat islets. The islets were pulse labelled for 15 min with [3H]leucine (present in rat insulin I and II) or [35S]methionine (unique to rat insulin II) and then incubated for a 165 min post-label (chase) period during which the majority of labelled proinsulin was converted to insulin but under conditions whereby greater than 95% of radiolabelled proinsulin or insulin was retained in the islets. The newly synthesized, labelled, insulin was analyzed by high performance liquid chromatography. Rat I and II insulin biosynthesis was stimulated by 16.7 mM glucose to the same extent.

Regulation of acetylcholinesterase secretion from neuronal cell cultures.--1. Actions of nerve growth factor, cytoskeletal inhibitors and tunicamycin.

The release of enzymatically active acetylcholinesterase was measured from two types of neuronal cell cultures. Evidence is presented that primary cultures of chick optic lobe and clonal rat PC12 cells released acetylcholinesterase by similar mechanisms. The secretion was selective for the tetrameric or larger molecule forms of acetylcholinesterase. Thus the chick primary cultures released the so-called G4 isoenzyme of acetylcholinesterase. The rat PC12 cells, after pretreatment with nerve growth factor, secreted mainly G4 acetylcholinesterase and a small amount of an isoenzyme sedimenting at 16S. The rate of secretion of acetylcholinesterase was regulated by the three types of agents used. (1) Acetylcholinesterase secretion was markedly increased by nerve growth factor. (2) Microtubule inhibitors (colchicine, taxol and nocodazole) suppressed the rate of release of acetylcholinesterase. (3) Acetylcholinesterase release was also decreased by an inhibitor of protein glycosylation, tunicamycin. We provide evidence that these three types of agents regulate acetylcholinesterase secretion not by a direct effect on secretion, but by modulatory effects on the synthesis, intracellular transport and turnover of the enzyme. (1) Nerve growth factor acts on acetylcholinesterase secretion via increased synthesis of messenger RNA. (2) Microtubule inhibitors act by preventing intracellular transport. (3) Tunicamycin acts by decreasing the intracellular activity of acetylcholinesterase, possibly via enhanced proteolytic breakdown.

Extraocular fast myosin heavy chain expression in the levator palpebrae and retractor bulbi muscles.

PURPOSE: To determine whether the levator palpebrae superioris (LPS) and the retractor bulbi (RB) muscles, which share contractile characteristics with extraocular muscles (EOMs), express fast EOM-specific myosin heavy chain (MyHC) in the rabbit and other mammalian species. METHODS: Cryostat sections of rabbit eye and limb muscles were stained by indirect peroxidase immunohistochemical procedures using monoclonal antibodies (MAbs), including one (4A6) against EOM-specific fast MyHC. Myosin heavy chain isoforms from these muscles were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the 4A6-reactive component was identified by immunoblotting. RESULTS: MAb 4A6 stained muscle fibers in rabbit LPS and RB. SDS-PAGE resolved a rabbit EOM-specific MyHC isoform (band 1) from two other components (bands 2 and 3) that comigrated with limb fast MyHCs. MAb 4A6 reacted only with band 1. Rabbit LPS and RB also displayed corresponding MyHC components with the same mobilities and immunoreactivities as bands 1 to 3 in the EOM. MAb 4A6 also stained muscle fibers in monkey and cat LPS, but it failed to stain muscle fibers in cat RB and rat LPS and RB. CONCLUSIONS: The expression of EOM-specific fast MyHC in EOM, LPS, and RB reflect their common developmental origin and similar contractile characteristics. These properties set them apart from other skeletal muscle groups. Eye muscles may constitute a distinct muscle group or allotype characterized by unique properties, including their propensity or resistance to disease.

Human extraocular muscles: unique pattern of myosin heavy chain expression during myotube formation.

PURPOSE: To study the myosin heavy chain composition of the human extraocular muscles (EOMs) during development. METHODS: EOMs from human fetuses of 8 to 22 weeks of gestation were studied with immunocytochemistry and gel electrophoresis. Antibodies specific against nine isoforms of myosin heavy chain (MyHC) were used in serial frozen sections. RESULTS: The developing EOMs had a delayed time course of myotube formation and a unique composition and distribution of MyHCs compared with human limb skeletal muscle. The primary myotubes coexpressed two developmental isoforms of MyHCI from the earliest stages. The third developmental MyHCI delineated the future orbital layer at 10 to 12 weeks of gestation. MyHC-slow tonic also appeared early, whereas MyHC alpha-cardiac and MyHC-extraocular, important components of adult EOM, were never detected at the gestational ages studied. CONCLUSIONS: The developmental features of the EOMs differed significantly from those reported for limb muscles of the corresponding ages. It is clear that the knowledge of limb muscle development does not fully apply to more specialized muscles, such as the eye muscles. The extreme complexity displayed by the EOMs probably reflects their distinct embryonic origin, innervation, and regulatory program of myogenesis.

Regulation of acetylcholinesterase by nerve growth factor in the pheochromocytoma PC12 cell line.

In the PC12 clonal nerve cell line derived from a rat pheochromocytoma, the activity of acetylcholinesterase (AChE) is regulated by nerve growth factor (NGF). The specific activity of AChE was significantly increased 2 days after exposure of PC12 cells to NGF (8 X 10(-8) M), and reached its maximal increase of 94% after 3 days. Thereafter the specific activity of AChE did not significantly vary during the following 7 days. AChE cytochemistry showed the enzyme activity to be localized predominantly in cisternae of the rough endoplasmic reticulum, with a strongly enhanced activity after NGF treatment.

Iliotibial band friction syndrome as exhibited in athletes.

Iliotibial band (ITB) friction syndrome is an overuse injury common in runners, cyclists, weight lifters, skiers, and soccer players. It is characterized by pain over the lateral femoral epicondyle caused by excessive friction between the ITB and the lateral femoral epicondyle.ITB friction syndrome can be prevented by using correct mechanics and training practices. Avoiding such errors, such as a swift change in playing surfaces or running excessive distances, can prevent this condition. Orthotics to correct mechanical problems also can prevent this injury. Stretching is not only a good treatment, it also is a good prophylaxis. Rest and the application of therapeutic modalities resolve most cases of ITB friction syndrome, but, in persistent cases, surgical intervention may be considered.

Access to health care in rural western New York State.

Persons living in rural counties often have limited access to health care. From a random sample, 1,332 households in six rural western New York counties were interviewed by telephone to identify what health care facilities are used when seeking professional health care what factors affect the preference for a health care facility and whether individuals perceive a shortage of health services in their communities. Seventy-nine percent of rural western New York individuals surveyed visited a physician between June 1988 and January 1990. The majority (83%) of individuals visited their regular health care source, which in most cases (81%) was a physician's private office. Factors related to a preference for some other health care source for the last visit included having traveled 20 or more miles to the visit (p < 0.01) and lack of overall satisfaction with the last visit (p < 0.001). Factors that varied by county of residency and were significantly associated with satisfaction included the type of health source used (p < 0.001), and the distance traveled to the last health care visit (p < 0.01). The majority of the respondents did not perceive a shortage of health care services in their communities probably because they have a lower expectation of health care accessibility.

Regulation of acetylcholinesterase activity by retinoic acid in a human neuroblastoma cell line.

The ability of retinoic acid (RA) to modulate acetylcholinesterase (AChE) activity in a human neuroblastoma cell line (LN-N-5) was examined. The specific activity of AChE was significantly increased 3 days after exposure of LA-N-5 to RA and reached its maximum values after 9 or more days of culturing. Dose-response experiments demonstrated that large increases of AChE occurred at RA concentrations between 10(-7) and 10(-6) M with maximum AChE values detected at 10(-6)-10(-5) M. Increased AChE activity paralleled neurite outgrowth in LA-N-5 cultures. These findings demonstrate that RA can regulate specific AChE activity in human neuroblastoma cells in a manner consistent with neuronal maturation.

Factors in the physician practice location puzzle: a survey of New York State residency-trained family physicians.

BACKGROUND: For the past 5 years fewer medical students have selected primary care specialties, and one-third of all physicians have indicated they will move in the next 5 years. These two factors make family physicians one of the most recruited specialties in medicine. METHODS: A questionnaire about practice profiles and factors that have an impact on a physician's location decision was mailed to all physicians who graduated from New York State family medicine residencies between 1970 and 1989. Data from completed responses were analyzed by year of graduation from residency, community size, and whether the responder remained in New York State or chose to locate outside New York State. RESULTS: There were 711 (46 percent) physicians who responded. The number of minorities remained stable at 14 percent during these years, but women graduates increased from 12 percent to 21 percent. The graduates in the 1980s, when compared with those in the 1970s, were more likely to be salaried, make less money, and to believe employment for the physician's spouse to be important in practice location. The 38 percent of responders from communities of fewer than 25,000 were less likely to be salaried, were more likely to practice in a group, worked more hours, offered a broader range of services including obstetrics, made less money, and placed less importance on availability of hospital consultants. Extended family, previous negotiated obligations, and geographic or climate issues were the reasons 64 percent of out-of-state responders gave for leaving New York. Spouse's opinion, hospital consultants, hospital services, colleague interaction, and after-hours coverage were most frequently rated as important factors for family physician practice location. CONCLUSIONS: Factors important in attracting new physicians to a community include the spouse's opinion, institutional and colleague support, and lifestyle issues.

Audit of the investigation and outcome of iron-deficiency anaemia in one health district.

The investigation of iron-deficiency anaemia (IDA) is a clinical problem which arises in virtually all branches of medicine. To audit the investigation of IDA, a computer-based laboratory record system was used to identify all women over 50 years of age and all men (n = 200) presenting to a single district laboratory with probable IDA in a six-month period. In 21 of 130 incident cases anaemia was clearly attributable to non-gastrointestinal disease. Of the remaining 109, 19% had investigation of both upper and lower gastrointestinal tract, 21% the upper gastrointestinal tract only, and 7% the lower gastrointestinal tract only. In 55 cases either no investigation was performed or only faecal occult blood tests. Eighteen months after presentation nine colorectal cancers, five gastric cancers and 11 peptic ulcers had been diagnosed; 21 patients had died, including two from colorectal cancers not detected when the IDA presented. This audit has revealed substantial underinvestigation of probable IDA, with serious but treatable conditions remaining undetected. Our findings, which we have no reason to believe are unrepresentative, indicate that policies are needed to ensure adequate investigation of IDA.

Expression of extraocular myosin heavy chain in rabbit laryngeal muscle.

The intrinsic laryngeal muscles of mammals are functionally heterogeneous, some of these muscles (e.g. the thyroarytenoid) contract extremely rapidly, like extraocular muscle, whilst others (e.g. the cricothyroid) contract as fast as limb fast muscle. The extraordinarily rapid contraction speed of extraocular muscles is associated with a fast myosin not found in limb muscles. In this work we explored the possibility that the thyroarytenoid muscle may also express this extraocular-specific fast myosin by raising a monoclonal antibody (mab 4A6) against its heavy chain. Electrophoretic separation of native isomyosins revealed that both the extraocular and the thyroarytenoid have two similar bands migrating ahead of bands found in limb fast or cricothyroid myosins. These two bands bound mab 4A6. The thyroarytenoid muscle can be divided into two divisions, a vocalis division which is important in phonation and an external division which functions in closing the glottis. Fibres in the vocalis are heterogeneous, some stain with mab 4A6, whilst others stain with mabs against limb myosin heavy chains. Fibres in the external division stain almost homogeneous with mab 4A6. The immunohistochemical staining pattern in the cricothyroid muscle resembled that of fast limb muscle: no fibres stained with mab 4A6. Thus, the high speed of contraction of the thyroarytenoid is associated with the same myosin heavy chain found in extraocular muscles, this characteristic is presumably an evolutionary adaptation for rapid closure of the glottis to enhance airway defense mechanisms.

Monospecific antibodies against the three mammalian fast limb myosin heavy chains.

Skeletal muscle fibres in mammalian limb muscles are of four types: slow, 2A, 2X, and 2B, each characterized by a distinct myosin heavy chain (MyHC) isoform. Existing monoclonal antibodies (mabs) against fast MyHCs lack fibre-type specificity across species and could not positively identify 2X fibres. In this work, mabs were raised against each of the fast MyHCs. These mabs were shown to be monospecific by Western blots and immunohistochemistry in the rat. The advantages of using these mabs for identifying the three fast fibre types and hybrid fibres expressing multiple isoforms were illustrated using rat tibialis anterior muscle. Immunohistochemical analyses confirmed the monospecificity of these mabs in the following additional species: mouse, guinea pig, rabbit, cat, and baboon. 2B fibres were absent in limb muscles of the cat and baboon. These mabs constitute a set of powerful tools for studying muscle fibre types and their transformations.