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Biomedical subjects

M Peterson

Publications and source records attributed to M Peterson.

At least 55 records · Page 3Linked to original sources

Spinous process osteotomies to facilitate lumbar decompressive surgery.

STUDY DESIGN: A technique for lumbar decompression using spinous process osteotomies is described, and the outcomes are studied prospectively. OBJECTIVE: To describe a technique that affords a wide exposure for decompression while minimizing damage to surrounding tissues, and to analyze the outcomes formally using the technique. SUMMARY OF BACKGROUND DATA: Commonly used techniques of lumbar decompression, which include bilateral takedown of paraspinal musculature and aggressive bony resection, can result in significant iatrogenic sequelae, whereas minimally invasive techniques often provide inadequate visualization and/or decompression. METHOD: Unilateral limited takedown of the multifidus is undertaken, followed by spinous process osteotomies at the involved levels. The spinous processes with the attached interspinous/supraspinous ligaments are then retracted. A complete "trumpeted" decompression is then undertaken. Fifty consecutive patients undergoing the procedure were analyzed prospectively and at follow-up by an independent observer using a validated functional outcome measure, a visual analog pain scale, and a patient satisfaction score. RESULTS: Functional outcome scores improved on average by 47%, pain levels were reduced by 66%, and high satisfaction rates were reported by 83% of patients. CONCLUSIONS: The technique affords excellent visualization and a wide area available for Kerrison use and angulation while minimizing destruction to tissues not directly involved in the pathologic process, including the paraspinal musculature as well as the interspinous/supraspinous ligament complex and facets. Additionally, it minimizes dead space and improves the cosmetic result.

Aged↗

Associative learning impairments in patients with frontal lobe damage.

The performance of 18 frontal lobe lesion (FL) and 10 frontal lobe dementia (FLD) patients on an associative memory test was compared with the performance of their matched normal controls. The FL group was severely impaired on cued and free recall and was moderately impaired on a recognition condition. Left FL patients performed the poorest on the cued and free recall conditions. The FLD patients were moderately impaired on the free recall condition only but there was a subgroup of FLD patients with additional left temporal atrophy who appeared severely impaired on both cued and free recall. These findings indicate that both left frontal and temporal lobe damage can impair associative learning and that this impairment is more strikingly seen with free rather than cued recall.

Adult↗

Population-based cohort study of microbial keratitis in Scotland: incidence and features.

OBJECTIVE: To investigate the incidence and features of bacterial, fungal and protozoal keratitis in Scotland. DESIGN: Prospective, population-based cohort study of all persons who developed culture proven microbial keratitis over an 8 month period. SETTING: West of Scotland, UK. SUBJECTS: Approximately 3,000,000 population. MAIN OUTCOME MEASURES: Incidence and risk factors for microbial keratitis. METHODS: All patients were included who had presumed microbial keratitis from which bacteria, fungi or Acanthamoeba was isolated from the corneal scraping by the hospital laboratory using a standardised protocol. In addition, contact lens wearing patients with pathognomonic features of Acanthamoeba keratitis, who yielded a negative culture result when referred on chlorhexidine therapy, were included if Acanthamoeba could be cultured from their lens storage case. RESULTS: The overall annual incidence of culture-proven microbial keratitis was 0.26 per 10,000 with a rate of 1.8 per 10,000 for contact lens wearers (all types, soft and rigid). Based on a previous pilot study of 'presumed' microbial keratitis in Glasgow, it was possible to estimate the incidence of expected 'presumed' microbial keratitis as 0.36 per 10,000 overall and 2.44 per 10,000 for contact lens wearers (all types). The incidence for Acanthamoeba keratitis was 1.49 per 10,000 soft contact lens wearers; this infection was not detected in the absence of contact lens wear nor with use of gas permeable or rigid contact lenses. CONCLUSIONS: 'Presumed' microbial keratitis from all causes, in the adult population, was approximately three times less common in the West of Scotland (0.36 per 10,000) than would be expected from a comparable retrospective study from Minnesota, USA for the years 1980-1988 (1.1 per 10,000). It was rare (approximately one case expected in 2 million per year) in the absence of pre-existing corneal disease, cosmetic contact lens wear or trauma. Ocular surface disease was the underlying cause predisposing to infection in 58% of cases, with an incidence of 'presumed' keratitis of 0.21 per 10,000 population; the highest incidence was found in the elderly population. Contact lens wear was responsible for 38% of cases, emphasising the importance of preventive hygiene and effective disinfection in this group. The estimated incidence of 'presumed' microbial keratitis in the West of Scotland associated with cosmetic wear (daily and extended use) of soft contact lenses was significantly less (P<0.05) than that expected from a prospective study in New England, America in 1985 (266 per 10,000, rather than 8.05 per 10,000). However, the estimated incidence for presumed microbial keratitis for the West of Scotland associated with wearing soft contact lenses for cosmetic purposes in the daily wear modality (266 per 10,000) was less, but not significantly less, than that found in the prospective American study (4.20 per 10,000). The daily wear mode for contact lenses is almost universal in the West of Scotland, where extended wear has never been recommended. Extended wear has been shown in the USA to be associated with an incidence of presumed microbial keratitis between five and ten times higher than that associated with daily wear. This explains the lower incidence we have observed and a difference with the US study for overall infection rates but not when associated with daily wear alone. The incidence of proven Acanthamoeba keratitis found in the Scottish study among wearers of soft contact lenses for daily wear cosmetic purposes was exceptionally high at 1.49 per 10,000.

Journal Article↗

Acanthamoeba keratitis in Scotland: risk factors for contact lens wearers.

OBJECTIVE: To investigate risk factors for Acanthamoeba keratitis amongst contact lens wearers in Scotland. DESIGN: Patients with Acanthamoeba keratitis in the Scottish study, all of whom wore contact lenses, were compared with 46 healthy asymptomatic contact lens-wearing controls. They were all visited at home for contact lens and environmental microbiological sampling. In addition, all 288 optical practices in the West of Scotland were polled for contact lens types and disinfecting solutions sold in 1995, and a sample, each of whom fitted more than 500 contact lenses per year, were polled for a second time. Independently, a poll was commissioned by the Eyecare Information Service in July/August 1995 to estimate the numbers of contact lens wearers in Scotland and the UK. Industry was polled for numbers of each contact lens disinfecting regimen sold in Scotland in 1995. SETTING: West of Scotland, UK. SUBJECTS: All contact lens wearers among the 3 million population of the West of Scotland Health Board Areas. MAIN OUTCOME MEASURES: Risk factors for Acanthamoeba infection and recommendations for its prevention. RESULTS: When Acanthamoeba infection occurred, patients' home water systems were frequently (54%) found to be colonised by this amoeba. Patients more frequently washed their storage cases in tap water than controls (P<0.05) with resulting contamination, kept storage cases wet rather than air drying them (P<0.05), and had coliform bacteria cultured from the storage case (P<0.05) and had viable Acanthamoeba within the storage case (P<0.0001). Overall, patients were found to have significantly more risk factors than controls (P<0.0001). The noncompliant use of chlorine tablet disinfection, or failure to disinfect contact lenses at all, was associated with increased risk (P<0.05). Ionic high water content contact lenses (FDA group 4 material), when used without disinfection or with non-compliant use of low chlorine (Soflab) tablet-based disinfection, were associated with increased risk of Acanthamoeba infection (P<0.05). In log-linear modelling of risky hygiene behaviours associated with contamination of storage cases with Acanthamoeba, the most significant behaviour was found to be use of the less effective disinfection methods (chlorine tablets or no disinfection). However further investigation showed that these methods were associated with an increased probability of rinsing the storage case in tap water, so that these two behaviours are confounded in the group studied. CONCLUSIONS: Failure to disinfect contact lenses, non-compliant use of chlorine tablets and/or introduction of tap water rinsing of storage cases were associated with increased risk of Acanthamoeba infection. New multipurpose solutions and hydrogen peroxide gave the lowest risk of Acanthamoeba infection, with no statistically significant difference between them. Ionic high-water content (FDA group 4) contact lenses were at increased risk of being associated with Acanthamoeba keratitis if used without effective disinfection (multipurpose solutions or hydrogen peroxide). The use of domestic tap water for contact lens and storage case hygiene must be avoided, as a chain-of-causation' was identified from the home water supply.

Journal Article↗

Enhanced learning of proportional math through music training and spatial-temporal training.

It was predicted, based on a mathematical model of the cortex, that early music training would enhance spatial-temporal reasoning. We have demonstrated that preschool children given six months of piano keyboard lessons improved dramatically on spatial-temporal reasoning while children in appropriate control groups did not improve. It was then predicted that the enhanced spatial-temporal reasoning from piano keyboard training could lead to enhanced learning of specific math concepts, in particular proportional math, which is notoriously difficult to teach using the usual language-analytic methods. We report here the development of Spatial-Temporal Math Video Game software designed to teach fractions and proportional math, and its strikingly successful use in a study involving 237 second-grade children (age range six years eight months-eight years five months). Furthermore, as predicted, children given piano keyboard training along with the Math Video Game training scored significantly higher on proportional math and fractions than children given a control training along with the Math Video Game. These results were readily measured using the companion Math Video Game Evaluation Program. The training time necessary for children on the Math Video Game is very short, and they rapidly reach a high level of performance. This suggests that, as predicted, we are tapping into fundamental cortical processes of spatial-temporal reasoning. This spatial-temporal approach is easily generalized to teach other math and science concepts in a complementary manner to traditional language-analytic methods, and at a younger age. The neural mechanisms involved in thinking through fractions and proportional math during training with the Math Video Game might be investigated in EEG coherence studies along with priming by specific music.

Child↗

Lack of developmental neurotoxicity of MN rgp 120/HIV-1 administered subcutaneously to neonatal rats.

The potential for neurotoxic effects was evaluated in rat off-spring after exposure in utero and/or during the neonatal period to a recombinant subunit vaccine of gp120 prepared from the MN strain of HIV-1 (MN rgp 120/HIV-1). Thirty pregnant female rats were given MN rgp120/HIV-1 with alum adjuvant, and 30 rats were given vehicle, once every 3 days from Day 1 of presumed gestation until parturition. One pup/sex/litter from treated and control group dams were given a daily subcutaneous injection, from Day 1 through Day 22 postpartum (PP) of vehicle, MN rgp120/HIV-1, MN rgp120/HIV-1 with alum, or MN rgp120/HIV-1 with QS-21 adjuvant. Neurobehavioral and physical development were evaluated (preweaning reflex and development, sexual maturation, motor activity, acoustic startle, passive avoidance, functional observational battery, and water M-maze testing), and tissues were processed for anatomical examination (whole and regional brain weights, and neuropathology). Administration of MN rgp120/HIV-1, with or without adjuvant, to pups did not cause any persistent effect on any parameter evaluated. Neurohistological examination did not reveal any pathological effects related to treatment. Thus, MN rgp120/HIV-1 alone or formulated as a vaccine does not cause neurotoxicity or developmental toxicity in neonatal rats after exposure in utero and/or during the neonatal period.

AIDS Vaccines↗

The inability of the nonobese diabetic class II molecule to form stable peptide complexes does not reflect a failure to interact productively with DM.

Sequence variability in MHC class II molecules plays a major role in genetically determined susceptibility to insulin-dependent diabetes mellitus (IDDM). It is not yet clear whether MHC class II polymorphism allows selective binding of diabetogenic peptides or regulates some key intracellular events associated with class II-restricted Ag presentation. In this study, we have employed gene transfer techniques to analyze the intracellular events that control peptide acquisition by the unique class II molecule expressed by nonobese diabetic mice (I-Ag7). This structurally unique class II molecule fails to demonstrate stable binding to antigenic peptides and fails to undergo the conformational change associated with stable peptide binding to class II molecules. The experiments reported here demonstrate that I-Ag7 can productively associate with two protein cofactors important in class II-restricted Ag presentation, invariant chain (Ii) and DM. DM participates in the removal of the Ii-derived class II-associated Ii chain peptide and the p12 degradation product from the I-Ag7 molecule. In addition, I-Ag7 undergoes a conformational change when DM is expressed within the APC. Finally, DM can mediate accumulation of peptide/class II complexes on the surface of APCs. Collectively, our experiments indicate that the failure of the I-Ag7 molecule to stably bind peptide cannot be attributed to a failure to interact with the DM or Ii glycoproteins.

Animals↗

N-terminal proANF in acute atrial fibrillation: a biochemical marker of atrial pressures but not a predictor for conversion to sinus rhythm. Digitalis in Acute Atrial Fibrillation (DAAF) Trial group.

BACKGROUND: Atrial filling pressures are increased in acute atrial fibrillation, which stimulates the release of atrial natriuretic factor pro-hormone, proANF. METHODS: In a randomized trial comparing digoxin with placebo in 216 patients, we investigated whether the baseline plasma level of N-terminal proANF is a predictor for conversion to sinus rhythm and the relation among N-terminal proANF, conversion to sinus rhythm, and changes in heart rate. RESULTS: N-terminal proANF was increased at baseline and decreased significantly in patients converting to sinus rhythm, whereas it was mainly unchanged in nonconverters. N-terminal proANF was not a predictor of conversion to sinus rhythm. A relation was found between relative changes in heart rate and N-terminal proANF in nonconverters. CONCLUSION: The level of N-terminal proANF does not predict conversion to sinus rhythm, which indicates that hemodynamics per se is not important. There is a correlation between relative changes in heart rate and N-terminal proANF in nonconverters.

Acute Disease↗

Placental pathology in systemic lupus erythematosus: a prospective study.

OBJECTIVES: Systemic lupus erythematosus and antiphospholipid antibody, often identified in patients with systemic lupus erythematosus, are associated with poor pregnancy outcome. This study distinguishes between the effect of each of these factors on gestational outcome and placental pathologic conditions in pregnant patients with systemic lupus erythematosus. STUDY DESIGN: Thirty-seven pregnancies and 40 placentas from 33 women with systemic lupus erythematosus were studied prospectively. RESULTS: Systemic lupus erythematosus alone, but not systemic lupus erythematosus activity, was associated with increased spontaneous abortions, preterm gestations, and fetal growth restriction. Placental correlates were ischemic-hypoxic change, decidual vasculopathy, decidual and fetal thrombi, chronic villitis, and decreased placental weight. Extensive infarction and fetal death were important antiphospholipid antibody-related findings. CONCLUSIONS: Decidual vasculopathy/coagulopathy appears to mediate the antiphospholipid antibody-related and much of the systemic lupus erythematosus-related deleterious effect on the placenta and gestational outcome. The presence of antiphospholipid antibody largely, but not invariably, predicts fetal death. Antiphospholipid antibody-independent chronic villitis may represent a second mechanism of systemic lupus erythematosus-related change.

Adult↗

Marimastat inhibits neointimal thickening in a model of human vein graft stenosis.

BACKGROUND: There is now accumulating evidence that matrix metalloproteinases (MMPs), the physiological mediators of matrix deposition and degradation, play an important role in the development of intimal hyperplasia following arterial bypass. This study investigated the effect of marimastat, an orally active specific MMP inhibitor, on neointima formation in cultured human saphenous vein. METHODS: Segments of human saphenous vein obtained from ten patients undergoing arterial bypass surgery were cultured for 14 days in serum-supplemented RPMI medium (controls) or in control medium supplemented with marimastat at three different concentrations (treatment groups). Following culture, half of each segment was prepared for histological examination and MMPs were extracted from the other half for gelatin zymography. RESULTS: Marimastat inhibited neointimal thickening in a concentration-dependent manner; inhibition was significant at 10(-5) and 10(-6) mol/l (P=0.006). This observation was paralleled by a significant reduction in the levels of MMP-2 and MMP-9 in the tissues. CONCLUSION: Marimastat significantly reduced neointimal thickening in this laboratory model. MMP inhibitors may offer a potential therapeutic strategy in the prevention of intimal hyperplasia.

Cells, Cultured↗

Analysis of a worksite health promotion program's impact on job satisfaction.

This study assessed the impact of participation in a health promotion program and engagement in healthy behaviors on job satisfaction. A survey response rate of 70% (n = 1,283) was obtained at a northern state university with an established worksite health promotion program. Significant differences in job satisfaction were obtained by education level, job classification, marital status, dependents, and regular exercise behaviors. No differences in job satisfaction were obtained by health promotion program involvement or any other health behavior other than regular exercise. Results suggest that health promotion programs do not significantly impact job satisfaction. Rather, job design and the psychosocial aspects of the work environment may be more influential in improving job satisfaction. Based on the results of this study, organizations attempting to improve employee health should provide health promotion programs and address the job itself. To improve job satisfaction, attention to the job itself is required.

Educational Status↗

Venous haemodynamics after total knee arthroplasty: evaluation of active dorsal to plantar flexion and several mechanical compression devices.

We performed a crossover study to evaluate the haemodynamic effect of active dorsal to plantar flexion and seven pneumatic compression devices in ten patients who had a total knee arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5MHz linear array probe, we assessed the augmentation of peak venous velocity and venous volume above and below the junction of the greater saphenous and common femoral veins in order to study both the deep and superficial venous systems. The pneumatic compression devices evaluated included two foot pumps (A-V Impulse System and PlexiPulse Foot), a foot-calf pump (PlexiPulse Foot-Calf), a calf pump (VenaFlow System) and three calf-thigh pumps (SCD System, Flowtron DVT and Jobst Athrombic Pump). The devices differed in a number of ways, including the length and location of the sleeve and bladder, the frequency and duration of activation, the rate of pressure rise, and the maximum pressure achieved. A randomisation table was used to determine the order of the test conditions for each patient. The enhancement of peak venous velocity occurred primarily in the deep venous system below the level of the saphenofemoral junction. The increases in peak venous velocity were as follows: active dorsal to plantar flexion 175%; foot pumps, A-V Impulse System 29% and PlexiPulse 65%; foot-calf pump, PlexiPulse, 221%; calf pump, VenaFlow, 302% and calf-thigh pumps, Flowtron DVT 87%, SCD System 116% and Jobst Athrombic Pump 263%. All the devices augmented venous volume, the greatest effect being seen with those incorporating calf compression. The increases in ml/min were found in the deep venous system as follows: foot pumps, A-V Impulse System 9.6 and PlexiPulse Foot 16.7; foot-calf pump, PlexiPulse, 38.1; calf pump, VenaFlow, 26.2; calf-thigh pumps, Flowtron DVT 61.5, SCD System 34.7 and Jobst Athrombic Pump 82.3. Active dorsal to plantar flexion generated 8.5 ml for a single calf contraction.

Aged↗

Dosage titration of a characterized competitive exclusion culture to inhibit Salmonella colonization in broiler chickens during growout.

Broiler chicks were spray treated on the day of hatch with titrated dosages (10(6), 10(7), or 10(8) anaerobic CFU) of a characterized competitive exclusion culture (CF3) and challenged orally on day 3 with 10(4) CFU of Salmonella typhimurium. On day 10, cecal contents from control and CF3-treated chicks were cultured for S. typhimurium to determine the minimal efficacious dosage of the CF3 culture. The experiment was repeated in three replicated trials. Resistance to Salmonella cecal colonization was dosage related and progressively enhanced at the 10(7)- and 10(8)-CFU dosages compared with the 10(6)-CFU dosage. The 10(7)-CFU dosage was selected as the minimal effective dosage and evaluated for efficacy during a 43-day broiler growout study. Six hundred broilers were spray treated on the day of hatch and compared with 600 controls. One-half of the control and CF3-treated birds were challenged orally on day 3 with 10(4) CFU of S. typhimurium and designated "seeders." The remaining unchallenged birds were designated "contacts." Compared with the controls, the recovery of Salmonella cells from the ceca of the CF3-treated broilers was significantly decreased (P < 0.01) in the challenged seeders on days 21 and 43 of growout. Salmonella contamination of floor pen litter was significantly reduced (P < 0.05) in pens of CF3-treated birds compared with controls. The transmission of Salmonella cells from seeder to contact birds in the same pens was decreased significantly (P < 0.01). The results indicated that treatment of broiler chicks on the day of hatch with the 10(7)-CFU dosage of CF3 culture effectively increased resistance to S. typhimurium challenge during growout to market age.

Animals↗

Surgical correction of primary hyperparathyroidism improves quality of life.

BACKGROUND: The SF-36 health status assessment tool is well suited for measuring the morbidity associated with primary hyperparathyroidism (HPT). The purpose of this study was to test the hypothesis that surgical correction of primary HPT leads to measurable improvement in patient reported functional health status and well-being. METHODS: For the past 4 years patients with primary HPT have been asked to complete the SF-36 and to provide additional demographic and condition-specific information for study before operation. They then completed the SF-36 again by mail 2 months and 6 months after operation. RESULTS: One hundred forty patients entered the study through March 1998; 110 patients completed follow-up at 2 months and 82 at 6 months. Marked impairment compared to population norms occurred before operation in 7 of 8 domains of health status. Substantial improvement occurred in 5 of 8 domains of health status at 2 months and in 6 of 8 domains at 6 months. Statistically significant improvement was demonstrated in limitations caused by physical and emotional role function, social function, bodily pain, and vitality. CONCLUSIONS: Successful operation to correct primary HPT significantly improves patient reported functional health status and quality of life. Most improvement is seen within 2 months, but additional improvement in both physical and mental function is seen at 6 months.

Adult↗

Measuring health-status improvement after surgery: experience with the SF-36.

The outcomes of care delivery are increasingly being measured and managed by health care providers and clinicians. The authors describe an outcomes monitoring program implemented in one tertiary care center that uses both generic and condition-specific instruments to monitor patient recovery after routine surgery. The SF-36 Health Survey was shown to be a useful tool for measuring changes in functional status and well-being after inguinal hernia repair, cholecystectomy, and parathyroidectomy. Recommendations for its successful adoption in a clinical setting are presented.

Activities of Daily Living↗