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Biomedical subjects

B Martin

Publications and source records attributed to B Martin.

At least 109 records · Page 6Linked to original sources
PubMed1999

Asthma self-management: do patient education programs always have an impact?

BACKGROUND: During the past 15 years, programs to improve self-management practices in adults with asthma have reported improvement in functional status and reduction of inappropriate use of health care services. However, these programs usually represent an ideal approach, applying multiple patient education methods. Consequently, when these programs are found to be efficacious, it is important to replicate the programs as well as to evaluate less complex methods that may be more appropriate for nonacademic health care settings. METHODS: We compared the following 3 standardized self-management treatments in a randomized, controlled trial: (1) a replication of the self-management program developed at a university medical center that was previously shown to be efficacious; (2) a modified version of this program including only the core elements; and (3) a usual-care program. Outcome measures included medication and inhaler regimen adherence, asthma symptoms, respiratory illness, functional status, and use of health care resources. RESULTS: All 3 groups improved on measures of respiratory illnesses, use of health care services, and functional status. Patients in both education groups did no better than the usual-care group. CONCLUSIONS: The results are inconsistent with the results of the first asthma self-management study at this institution and with those of efficacy studies of similar programs. Two factors, selection of the patient population and historical changes in asthma treatment, most likely contributed to the lack of impact of the self-management programs. As a result of the improved standards for usual care due to both factors, the opportunity to effect patient outcomes was substantially reduced.

Administration, Inhalation↗
PubMed1999

Lobeline: structure-affinity investigation of nicotinic acetylcholinergic receptor binding.

(-)Lobeline (1) and (-)nicotine (2) bind at neuronal nicotinic cholinergic (nACh) receptors with high affinity (K(i) = 4 and 2 nM, respectively). Previous attempts to determine whether lobeline fits the currently accepted nicotinic pharmacophore model have led to suggestions that the carbonyl function, rather than the hydroxyl group, is a major contributor to binding. Interestingly, however, it has never been empirically demonstrated that either oxygen function is actually required for interaction with the receptor. In the present investigation we systematically examined a number of abbreviated analogues of lobeline and found that removal of either one or both oxygen functions reduces the affinity of lobeline by at least 25-fold; furthermore, oxidation of the (-)lobeline hydroxyl group (to afford lobelanine) or reduction of the carbonyl group (to afford lobelanidine) also resulted in decreased affinity. Although it is likely that both oxygen functions contribute to the high affinity of (-)lobeline at nACh receptors, it is concluded that the presence of both oxygen functions is not a requirement for binding; that is, replacement of the (-)lobeline hydroxyl group with a chloro group had no effect on affinity. Another finding of the present investigation is that removal of either one or both oxygen functions of lobeline results in compounds that retain the analgesic activity and potency of (-)lobeline, indicating that there is no direct relationship between neuronal nicotinic cholinergic (primarily alpha(4)beta(2) type) receptor affinity and spinal analgesia as measured in the tail-flick assay.

Analgesics↗
PubMed1999

Synthesis and oxidative insolubilization of cell-wall proteins during osmotic stress.

The cell walls in the new white roots of jack pine (Pinus banksiana Lamb.) were observed to constrict around the shrinking protoplast of osmotically stressed roots, and pressure was maintained via an apparent adjustment of cell-wall size and elasticity. These elastic alterations of the cell wall permitted the root cells to maintain full turgor despite the loss of most of the water in the tissue. The constriction of the root cell wall around the dehydrating protoplasts to maintain turgor may reflect changes in cell wall structure. We found that these shrinking root cells synthesize and secrete into the intercellular fluid a set of proteins. These proteins become tightly associated (i.e. guanidine HCl- and sodium dodecyl sulfate-insoluble) with the cell wall but can be released from the matrix, after briefly boiling in 0.1% sodium dodecyl sulfate, by the combination of guanidine HCl, CaCl2 and dithiothreitol. However, these cell-wall proteins became insoluble with time. The proteins could subsequently be destructively extracted from the wall with acid NaClO2 treatments. After these proteins were incorporated into the cell walls, the roots adopted a new, smaller maximal tissue volume and elastic coefficients returned to normal levels.

Amino Acid Sequence↗
PubMed1999

M-cadherin and its sisters in development of striated muscle.

Cadherins are calcium-dependent, transmembrane intercellular adhesion proteins with morphoregulatory functions in the development and maintenance of tissues. In the development of striated muscle, the expression and function of mainly M-, N-, and R-cadherin has been studied so far. While these three cadherins are expressed in skeletal muscle cells, of these only N-cadherin is expressed in cardiac muscle. In this review, M-, N-, and R-cadherin are discussed as important players in the terminal differentiation and possibly also in the commitment of skeletal muscle cells. Furthermore, reports are described which evaluate the essential role of N-cadherin in the formation of heart tissue.

Animals↗
PubMed1999

When is urokinase treatment an effective sole or adjunctive treatment for acute limb ischemia secondary to native artery occlusion?

BACKGROUND: Intra-arterial thrombolytic therapy is currently a therapeutic option for the treatment of acute limb ischemia. A recent large prospective randomized trial (TOPAS) comparing lytic therapy and operative intervention showed that both forms of treatment had similar results in terms of amputation-free survival. However, the exact role for lytic treatment is unclear. METHOD: Over a 4-year period we treated 60 cases of acute limb ischemia in 57 patients secondary to native artery occlusion with thrombolytic therapy with urokinase. All patients were evaluated at 1 week, 1 month, and then at 3-month intervals posttreatment. Follow-up evaluations included pulse examination, pulse volume recordings, and duplex examinations to confirm arterial patency. No patients were lost to follow-up with a range of 8 to 54 months (mean 26). RESULTS: Of these 60 native arterial occlusions, complete lysis was achieved in 46 cases (76%). Of these 46 cases, 18 required lysis only, 19 cases (9 iliac, 7 superficial femoral artery (SFA), and 3 popliteal) required angioplasty of lesions uncovered by clot lysis, and 9 patients had lysis and angioplasty of iliac arteries followed by infrainguinal bypasses. Eight of the 57 patients (14%) who had been asymptomatic presented with symptoms limited to new onset claudication, all of which were successfully lysed. Cumulative patency for the 43 successful cases was 90% +/- 5% at 1 year and 75% +/- 4% at 2 years. The 1-year amputation-free survival for all native artery occlusions was 85% +/- 6%. CONCLUSION: Thrombolysis with urokinase simplified the treatment of native arterial occlusion proving to be the sole therapy in 18 (29%) patients or a valuable adjunct by facilitating the angioplasty of arterial lesions and avoiding open surgery in 60% of patients treated. In addition, the correction of inflow lesions reduced the magnitude of required subsequent bypass procedures to achieve limb salvage. In conclusion, successful thrombolysis of native artery occlusion provided durable arterial patency and limb salvage, particularly in patients with new onset claudication.

Acute Disease↗
PubMed1999

Vascular aspects in the pathophysiology of glaucomatous optic neuropathy.

Glaucoma remains a major eye illness with unknown etiology. Although elevated intraocular pressure is clearly a major risk factor, vascular deficits may contribute to initiation and progression of glaucoma. When intraocular pressure is acutely elevated in healthy individuals, the resistance index (derived from the peak systolic and end-diastolic velocities and an indirect index of vascular resistance distal to the site of measurement) in the central retinal and posterior ciliary arteries increases progressively. This result implies that mechanical and vascular factors may be coupled in such a way that perfusion of the retina and optic nerve head may be influenced by changes in the intraocular pressure. Further, at night, when ophthalmic artery flow velocities fall as arterial blood pressure falls in glaucoma patients, the risk of disease progression may be increased. The constancy of these same flow velocities in age-matched healthy individuals points to a possible vascular autoregulatory defect in glaucoma. In addition, in normal-tension glaucoma, vasodilation (CO2 inhalation) normalizes retrobulbar arterial flow velocities, hinting that some vascular deficits in glaucoma may be reversible. Finally, Ca2+ channel blockade improves contrast sensitivity in patients with normal-tension glaucoma, who also show increased retrobulbar vessel flow velocities, a result suggesting that visual function loss may be linked to ocular ischemia. Emerging evidence points to a role of ischemia in the pathogenesis of glaucoma, suggesting that treatments designed to improve ocular blood flow may benefit glaucoma patients.

Animals↗
PubMed1999

High pre-treatment serum hepatitis B virus titre predicts failure of lamivudine prophylaxis and graft re-infection after liver transplantation.

BACKGROUND/AIMS: Orthotopic liver transplantation has an established role for the treatment of patients with chronic liver failure secondary to hepatitis B virus (HBV) infection. Unfortunately, recurrent infection of the graft can be associated with aggressive disease, and with diminished graft and patient survival. Currently, the role of nucleoside analogues for prevention of graft re-infection is being evaluated. Preliminary results are encouraging, but treatment failure has been associated with emergence of drug-resistant virus. METHODS: We have studied ten consecutive patients who received lamivudine prophylaxis for prevention of HBV graft reinfection. Sequential sera, collected prelamivudine then during treatment before and after liver transplantation, were examined. Conventional serological markers were measured, as were serum viral DNA levels with a sensitive quantitative polymerase chain reaction assay. RESULTS: Lamivudine treatment effected a reduction in serum HBV levels, but six patients still had measurable viral DNA at the time of transplantation. Five patients developed graft re-infection with lamivudine-resistant virus. Resistant virus emerged 8 to 15 months post-transplant. The likelihood of emergence of resistant virus was related to the pre-treatment serum HBV titre. Persistent serum viral DNA positivity and evidence of graft re-infection during the early post-transplant period did not predict the subsequent emergence of resistant virus. CONCLUSIONS: Our observations suggest that the resistant species may be present in the viral quasispecies in the serum and liver of patients with high-level replication prior to lamivudine exposure. The resistant species can persist during lamivudine treatment prior to transplantation, and emerge following transplantation. These observations suggest strategies which might prevent the emergence of drug-resistant species, and imply that graft re-infection may be a preventable phenomenon.

Antiviral Agents↗
PubMed1999

A place to care: the homebound elderly.

As America's elderly population continues to age, accessing adequate primary health care becomes more difficult. A survey of 22 homebound elderly people examined their acceptance of the expanded role functions of nurse practitioners to meet primary care needs in their homes. Chi-square analyses correlated participants' answers to demographic information. Only the variables of income and religion indicated statistical significance (P < .05) when correlated with expanded functions. Protestants, elders with no religious affiliation, and those with incomes below $20,000 indicated they would allow nurse practitioners to perform more expanded role functions than Catholics and those with higher incomes would. Generalizability is limited because of the small sample size, indicating a need for additional research with larger samples and more diverse populations.

Aged↗
PubMed1999

Influence of the composition of Alpine highland pasture on the chemical, rheological and sensory properties of cheese.

A study was undertaken to compare the chemical and sensory characteristics of Abondance cheeses made with milk from animals grazing areas within the same highland pasture, but with different predominant plants. Nine cheeses made during the last 3 d of three successive 7 d periods were evaluated. The animals grazed on the southern side of the highland pasture during the first period (15-21 June), on the northern side during the second period (22-29 June) and returned to the southern side for the third period (30 June-6 July). The gross composition of the cheeses did not vary between periods. 'North' cheeses contained more plasmin, gamma-casein, alpha s1-I-casein and water-soluble N than 'south' cheeses. Both sensory and instrumental measurements indicated that north cheeses were less firm, stickier and more easily fractured than south cheeses. North cheeses were also more salty, bitter and persistent. Their overall aroma was more intense and they had more intense sour, burnt, toasted, fermented vegetable and sweat aromas, but less intense toffee, exotic fruit and acid milk aromas. The texture differences noted between the cheeses from milk produced on the two areas may come from differences in primary proteolysis, partly due to different amounts of plasmin and plasminogen in milk and in cheeses. The aroma differences were related to differences in volatile compounds. Some compounds had a microbial origin, while some others may have come from the pasture.

Animal Feed↗
PubMed1999

Hepatitis C viral load, genotype and histological severity in patients with bleeding disorders.

We report the relationship between hepatitis C virus (HCV) titre, liver histology and HCV genotype in patients with bleeding disorders. One hundred and thirty-two RIBA-2-positive patients, including 56 who were also HIV positive, were identified at our centre. Fifty of these patients, including nine who were HIV infected, underwent percutaneous liver biopsy. Liver histology was assessed using a modified histological activity index (HAI). Qualitative serum HCV PCR was positive in 87 (87%) of the 101 patients tested including 43 of 50 biopsied patients. HCV RNA titres, measured by quantitative PCR, were significantly higher in HIV-positive patients compared with HIV-negative patients (P < 0.05) but were not related to HAI, mean factor concentrate usage, duration of HCV infection or HCV genotype. There was no relationship between HCV genotype and HAI. Qualitative HCV PCR was positive in 30 of 43 liver biopsies tested. Biopsy PCR-positive and -negative cohorts were not distinguished by HAI or serum HCV titre. We conclude that although serum HCV PCR is useful in confirming the presence of HCV infection in patients with bleeding disorders, little meaningful information concerning the severity of the disease can be obtained from serum HCV quantification.

Adult↗
PubMed1999

Muscle responses to simulated torque reactions of hand-held power tools.

The aim of this work was to investigate physiological responses to torque reaction forces produced by hand-held power tools used to tighten threaded fasteners. Such tools are used repetitively by workers in many industries and are often associated with upper limb musculoskeletal complaints. The tools considered for stimulation in this study had straight handles and required from 100 to 400 ms to tighten fasteners to a peak torque of 1.0 to 2.5 Nm and from 50 to 150 ms for the torque to decay to zero. A tool stimulator was constructed to apply a programmed torque profile to a handle similar to that of a straight in-line power screwdriver. Wrist flexor and extensor surface EMGs and handle position were recorded as subjects held handles subjected to controlled torque loads that tended to flex the wrist. It was found that: (1) very high EMG values occurred even though torques were of short duration (50 to 600 ms) and the peak torques were low (7-28% of maximum strength); (2) high EMGs in anticipation of torque are directly related to torque build-up rate and peak torque; (3) high peak flexor and extensor EMGs during and following torque onset are related to torque build-up rate and peak torque; (4) minimum time of peak EMGs of 72-87 ms following the onset of torques with 50 ms build-up suggests the contribution of an extensor muscle stretch reflex component; delayed peak for longer build-ups suggests a central control of muscle force in response to torque; (5) angular excursions of handles increase with decreasing torque build-up time and increasing torque magnitude causes increasing eccentric work; (6) the results show that the slow torque build-up times (450 ms) correspond to minimum peak EMGs; and (7) accumulated EMGs increase with increasing torque and torque build-up times. Further studies are needed to evaluate fatigue and musculoskeletal injuries associated with prolonged periods of tool use.

Adult↗
PubMed1999

Dorzolamide, visual function and ocular hemodynamics in normal-tension glaucoma.

The purpose of this study was to determine how a topical carbonic anhydrase inhibitor, dorzolamide, alters visual function and ocular blood flow in persons with normal-tension glaucoma. Eighteen normal tension glaucoma patients, after washout of other ocular medications, were treated for four weeks with 2% dorzolamide, three times daily. A control group of eleven other normal-tension glaucoma patients received placebo eye drops. Patients were studied before treatment, and after two and four weeks of treatment. Each study included assessment of central visual function (contrast sensitivity), intraocular pressure (IOP), and several aspects of ocular hemodynamics, including measures of retinal arteriovenous passage time, retinal arterial and venous diameters, and flow velocities in the ophthalmic, central retinal, and posterior ciliary arteries. Dorzolamide significantly reduced IOP at two and four weeks (each p<0.01), and at the same time increased contrast sensitivity at both three and six cycles per degree (each p<0.05). Neither of these variables changed significantly in the control group. Dorzolamide also accelerated retinal arteriovenous passage time of fluorescein dye, at constant retinal arterial and venous diameters (p<0.05), but failed to change flow velocities in any retrobulbar vessel. The ability of dorzolamide to improve contrast sensitivity in persons with normal-tension glaucoma may be related to either IOP reduction or altered ocular perfusion.

Blood Pressure↗
PubMed1999

Resuscitation with lactated Ringer's solution in rats with hemorrhagic shock induces immediate apoptosis.

BACKGROUND: We hypothesize that different resuscitative fluids may immediately affect the degree of apoptosis after hemorrhagic shock. METHODS: Rats (n = 35) were hemorrhaged 27 mL/kg over 5 minutes followed by 1 hour of shock, then resuscitation over 1 hour. The six treatment groups were sham hemorrhage, sham resuscitation, whole blood resuscitation, lactated Ringer's solution (LR) resuscitation with three times the volume bled, sham hemorrhage with LR infusion, and 7.5% hypertonic saline resuscitation (9.7 mL/kg). Liver and small intestine were harvested immediately after resuscitation. Apoptosis was evaluated by using in situ cell death detection method. RESULTS: Resuscitation with LR resulted in a significant increase in small intestinal and liver apoptosis. Animals that received LR infusion without hemorrhage had an increased level of apoptosis in the intestine. Apoptosis in the intestine was observed in both the mucosa and muscularis externa. There was no increase in apoptosis in either organ in the animals resuscitated with sham resuscitation, whole blood, and hypertonic saline compared with the sham hemorrhage group. CONCLUSION: Resuscitation with LR solution after hemorrhagic shock increased immediate cell death by apoptosis in both the small intestine and liver. There was no significant increase in apoptosis in the animals resuscitated with hypertonic saline, whole blood, or in unresuscitated animals. Thus, the type of resuscitation fluid used may affect the apoptotic cellular response to shock.

Animals↗
PubMed1999

Biosynthesis and immunolocalization of Lewis a-containing N-glycans in the plant cell.

We recently demonstrated the presence of a new asparagine-linked complex glycan on plant glycoproteins that harbors the Lewis a (Lea), or Galbeta(1-3)[Fucalpha(1-4)]GlcNAc, epitope, which in mammalian cells plays an important role in cell-to-cell recognition. Here we show that the monoclonal antibody JIM 84, which is widely used as a Golgi marker in light and electron microscopy of plant cells, is specific for the Lea antigen. This antigen is present on glycoproteins of a number of flowering and non-flowering plants, but is less apparent in the Cruciferae, the family that includes Arabidopsis. Lea-containing oligosaccharides are found in the Golgi apparatus, and our immunocytochemical experiments suggest that it is synthesized in the trans-most part of the Golgi apparatus. Lea epitopes are abundantly present on extracellular glycoproteins, either soluble or membrane bound, but are never observed on vacuolar glycoproteins. Double-labeling experiments suggest that vacuolar glycoproteins do not bypass the late Golgi compartments where Lea is built, and that the absence of the Lea epitope from vacuolar glycoproteins is probably the result of its degradation by glycosidases en route to or after arrival in the vacuole.

Animals↗
PubMed1999

Peripapillary retinal blood flow in normal tension glaucoma.

AIMS: To determine if normal tension glaucoma (NTG) patients differ from age matched controls in blood flow to the peripapillary retina, as measured with confocal scanning laser Doppler flowmetry (cSLDF; "Heidelberg retinal flowmetry"). METHODS: 12 NTG patients and 12 age matched controls were compared using (a) 10 x 10 pixel boxes (the instrument default sample size), taken from the nasal and temporal peripapillary retina, (b) the average from two of these boxes, and (c) every qualifying pixel within the peripapillary retina. RESULTS: Patients and controls did not differ in blood flow measured using the default sample from a single 10 x 10 pixel box, placed in either the temporal or nasal peripapillary retina, or expressed as the average from these two boxes. However, in histograms using every pixel from the peripapillary retina, NTG patients displayed significantly higher percentages of minimal flow pixels (defined as less than one arbitrary unit of flow: 30% v 19%, p < 0.01), and significantly lower flow in the 25th, 50th, and 75th percentile flow pixel (each p < 0.05) than did age matched controls. CONCLUSION: NTG is characterised by reduced blood flow in the peripapillary retina, a result suggesting that blood flow deficits accompany, and perhaps may contribute to, disease development in these patients.

Blood Flow Velocity↗