Comment on "Monitoring the transitions of the charge-induced reconstruction of Au(110) by reflection anisotropy spectroscopy".
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Comment↗
Biomedical subjects
C A Lucas
Publications and source records attributed to C A Lucas.
The XMaS beamline at ESRF: instrumental developments and high-resolution diffraction studies.
The beamline, which is situated on a bending magnet at ESRF, comprises a unique combination of instrumentation for high-resolution and magnetic single-crystal diffraction. White-beam operation is possible, as well as focused and unfocused monochromatic modes. In addition to an eleven-axis Huber diffractometer, which facilitates simple operation in both vertical and horizontal scattering geometries, there is an in-vacuum polarization analyser and slit system, mirrors for harmonic rejection, sub 4.2 K and 1 Tesla magnetic field sample environment, plus a diamond phase plate for polarization conditioning. The instrumentation developed specifically for this beamline is described, and its use illustrated by recent scientific results.
Journal Article↗
Electrophoretic and immunochemical evidence showing that marsupial limb muscles express the same fast and slow myosin heavy chains as eutherians.
Limb muscles of eutherian (placental) mammals express a slow and three fast isoforms of myosin heavy chain (MyHC), but little is known about marsupial MyHCs. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of limb MyHCs from seven marsupial species, spanning two orders, revealed four components, each of which specifically cross-reacted in Western blots with a monoclonal antibody (mAb) against a corresponding eutherian MyHC. For all seven species, the relative mobility of the band identified by each mAb matched that in the rat, suggesting that the four are homologous to eutherian slow, 2B, 2X and 2A MyHCs, respectively, in the order of decreasing mobility. Immunohistochemical analysis of fast marsupial limb muscles identitied four different fiber populations whose relative fiber size spectra (IIA<slow=IIX<IIB) are consistent with corresponding eutherian fiber types. These results show that the four MyHC genes were shared by the common therian ancestor, and suggest that other eutherian fiber type specific properties may apply to marsupial muscles.
Animals↗
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.
Animals↗
Jaw-closing muscles of kangaroos express alpha-cardiac myosin heavy chain.
The masseter muscle of eutherian grazing mammals typically express beta or slow myosin heavy chain (MyHC). Myosins in the masseter of 4 species of kangaroos and a slow limb muscle of one of them were compared with their cardiac myosin by pyrophosphate and sodium dodecyl sulphate (SDS) gel electrophoresis, immunoblotting and immunohistochemistry. It was found that ventricular muscle contains three isoforms homologous to V1 (alpha-MyHC homodimer), V2 (heterodimer) and V3 (beta-MyHC homodimer) of eutherian cardiac muscle, and that the masseter contained V1, with traces of V2 and V3, in great contrast to eutherian ruminants, which express only V3. A polyclonal antibody (anti-KJM) was raised in rabbits against red kangaroo masseter myosin. After cross-absorption against limb muscle myofibrils, anti-KJM specifically reacted in Westerns with MyHCs from masseter but not limb muscles, and immunohistochemically with masseter, but not limb muscle fibers. In pyrophosphate Western blots, anti-KJM reacted with V1 but not with V3. However, a monoclonal antibody specific for eutherian slow myosin stained all kangaroo slow muscle fibers but only weakly stained scattered fibers in the masseter. The SDS-PAGE revealed that light chain composition of masseter and ventricular myosins is identical, but isoforms of both light chains of kangaroo limb slow myosin were observed. These results confirm that kangaroo jaw muscle express alpha-MyHC rather than beta-MyHC. The difference in MyHC gene expression between marsupial and eutherian grazers may be related to the fact that kangaroos are not ruminants, and have only a single chance to comminute food into fine particles, hence the need for the greater speed and power of muscle contraction associated with V1 containing muscle fibers.
Animals↗
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.
Cell Differentiation↗
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.
Activities of Daily Living↗
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.
Animals↗
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.
Animals↗
Psychiatric disorders and functional impairment in patients with persistent dizziness.
OBJECTIVE: To determine the prevalence and predictors of psychiatric dizziness and to measure functional impairment associated with dizziness. DESIGN: Consecutive outpatients with a chief complaint of dizziness. SETTING: Four outpatient clinics at a military teaching hospital. PATIENTS: 100 dizzy patients and 25 control patients. MEASUREMENTS AND MAIN RESULTS: Structured psychiatric interviews were conducted using the Diagnostic Interview Schedule, and functional status was assessed with the Sickness Impact Profile and the 20-item MOS (Medical Outcomes Study) Short-Form. Psychiatric disorders were a primary or contributory cause of dizziness for 40% of the dizzy patients. Compared with the control patients, the dizzy patients had a higher lifetime (46% vs 32%) as well as recent (37% vs 20%) prevalence of axis I disorders. The greatest differences were in disorders of depression and somatization. The dizzy patients had a higher lifetime prevalence (23% vs 8%) as well as recent history (11% vs 0%) of major depression or dysthymia. Also, somatization disorders were strikingly more common among the dizzy patients than among the control patients (37% vs 8%, p = 0.005), with the dizzy patients reporting more than three times as many psychiatric or unexplained physical symptoms (5.2 vs 1.5). Age < 40 years, related complaints of weakness or headaches, and dizziness provoked by hyperventilation or standing were independent predictors of psychiatric dizziness. The dizzy patients reported moderate functional impairment, which was most severe among those with psychiatric disorders. CONCLUSIONS: Persistent dizziness is associated with increased functional impairment and psychiatric comorbidity, particularly depression and somatization. Moreover, psychiatric disorders aggravate the impairment that occurs with dizziness alone.
Aged↗
Learning climate and students' achievement in a medicine clerkship.
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Attitude of Health Personnel↗
Causes of persistent dizziness. A prospective study of 100 patients in ambulatory care.
OBJECTIVE: To determine the causes of persistent dizziness in outpatients. DESIGN: Consecutive adult outpatients presenting with a chief complaint of dizziness. SETTING: Four clinics (internal medicine, walk-in, emergency room, and neurology) in a teaching hospital. PATIENTS: Of 185 patients presenting during the 10-month study period, 51 (28%) had minimal or no dizziness at 2-week follow-up. Of the remaining 134 patients, 100 completed the study protocol (mean age, 62 years; range, 20 to 85 years). MEASUREMENTS: Evaluation included a detailed study questionnaire, standardized physical examination, vestibular testing by a neuro-ophthalmologist, laboratory tests, audiometry, and a structured psychiatric interview. Data were abstracted onto a standard form and reviewed by three raters. Raters independently assigned diagnoses using explicit criteria, with the final cause determined by consensus. RESULTS: Primary causes of dizziness included vestibular disorders (54 patients), psychiatric disorders (16 patients), presyncope (6 patients), dysequilibrium (2 patients), and hyperventilation (1 patient); dizziness was multicausal in 13 patients and of unknown cause in 8 patients. Many of those with a single primary cause, however, had at least one other condition contributing to their dizziness; only 52% of patients had a single "pure" cause. Thirty patients had a potentially treatable primary cause, the most common being benign positional vertigo (BPV) (16%) and psychiatric disorders (6%). Central vestibulopathies detected in 10 patients were presumably vascular or idiopathic in origin. No brain tumors or cardiac arrhythmias were found. CONCLUSIONS: Vestibular disease and psychiatric disorders are the most common causes of persistent dizziness in outpatients. In about 50% of patients with dizziness, more than one factor causes or aggravates symptoms. Life-threatening causes were rare, even in our elderly population.
Adult↗
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.
Adult↗
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.
Journal Article↗
Rural medicine and the closed society. Pregnancy outcomes among Amish and non-Amish women.
A rural family practitioner may be responsible for the general medical and obstetric needs of a closed population such as the Old Order Amish. Until recently, the Amish in southern New York State have preferred to receive obstetric care in the home from traditional Amish midwives. Acceptance of prenatal care and hospital deliveries by rural physicians appears to be increasingly frequent among Amish primiparas in southern New York State, while non-Amish in the area have been seeking these services for decades regardless of parity. This retrospective chart review examines first pregnancy outcomes of Amish (N = 39) and non-Amish (N = 145) women who delivered their babies at a rural hospital in southern New York State during a four-year period. Little difference was found between the two groups of women regarding the overall good health of their first babies. In the Amish population there was less variability in maternal age, season in which the birth occurred, labor duration, and birth weight of babies. The Amish had their first child an average of one year later than the non-Amish. While research on a larger sample will be necessary to fully explore Amish vs non-Amish variances, this study demonstrates the effect that traditions and customs of a closed society such as the Amish may have on obstetric practice.
Adult↗
Intracellular acidification inhibits the proliferative response in BALB/c-3T3 cells.
One of the earliest events to occur upon the addition of serum to quiescent cells is an increase in the intracellular pH (pHin). The relationship between this pH change and proliferation is not known. In the present study, we investigate the consequences of acidifying the cytosol using the weak acid, 5', 5"-dimethyl oxazolidine 2,4-dione (DMO). At a concentration of 50 mM, DMO inhibits the serum-induced increases in pHin, DNA synthesis, and cell number. This concentration of DMO is shown not to inhibit the steady-state rate of mitochondrial respiration and not to inhibit DNA synthesis in a pH-independent fashion. The effects of DMO treatments are also shown to be reversible, indicating that this compound is not cytotoxic. These observations indicate that DMO inhibits cell proliferation by lowering intracellular pH. One important event that must occur prior to the initiation of DNA synthesis is an elevated rate of protein synthesis. The rate of protein synthesis in situ is extremely pH sensitive. Addition of 50 mM DMO to serum-stimulated cultures reduces the rate of leucine incorporation to unstimulated levels. These observations suggest that cytoplasmic acidification may inhibit proliferation through its effects on protein synthesis.
Animals↗
Stimulation by ATP of proinsulin to insulin conversion in isolated rat pancreatic islet secretory granules. Association with the ATP-dependent proton pump.
Isolated rat pancreatic islets were pulse-labeled for 5 min with [3H]leucine then chased for 25 min, during which time endogenously labeled [3H]proinsulin becomes predominantly compartmented in immature secretory granules. The islets were then homogenized in isotonic sucrose (pH 7.4) and a beta-granule preparation obtained by differential centrifugation and discontinuous sucrose gradient ultracentrifugation. This preparation was enriched 8-fold in beta-granules. Aside from contamination with mitochondria and a limited number of lysosomes, the beta-granule preparation was essentially free of any other organelles involved in proinsulin synthesis and packaging (i.e. microsomal elements and, more particularly, Golgi complex). Conversion of endogenously labeled [3H]proinsulin was followed in this beta-granule fraction for up to 2 h at 37 degrees C in a buffer (pH 7.3) that mimicked the cationic constituents of B-cell cytosol, during which time 92% of the beta-granules remained intact. Proinsulin conversion was analyzed by high performance liquid chromatography. The rate of proinsulin conversion to insulin was stimulated by 2.2 +/- 0.1-fold (n = 6) (at a 60-min incubation) in the presence of ATP (2 mM) and an ATP regenerating system compared to beta-granule preparations incubated without ATP. This ATP stimulation was abolished in the presence of beta-granule proton pump ATPase inhibitors (tributyltin, 2.5 microM, or 1,3-dicyclohexylcarbodiimide, 50 microM). Inhibitors of mitochondrial proton pump ATPases (sodium azide, 20 mM, or oligomycin, 10 micrograms/ml) had no effect on the ATP stimulation of proinsulin conversion. When granules were incubated in a more acidic buffer (pH 5.5), proinsulin conversion was increased relative to that at pH 7.3. At pH 5.5, ATP no longer stimulated conversion, and tributyltin and 1,3-dicyclohexylcarbodiimide had no effect. Disrupted granules only converted proinsulin to a limited extent, and neither ATP nor the inhibitors affected conversion. It is therefore suggested that ATP stimulation of proinsulin conversion in isolated, intact, beta-granules is secondary to intragranular acidification by an ATP-dependent proton pump (reflecting the low pH optimum for proinsulin conversion), rather than ATP dependence of converting activity per se.
Adenosine Triphosphatases↗
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.
Animals↗