Biomedical subjects

J M Lynch

Publications and source records attributed to J M Lynch.

At least 37 records · Page 2Linked to original sources

PubMed2001

The impact of flow rate (simulated leaching) on plasmid transfer frequency between bacteria in a model rhizosphere system.

AIMS: To investigate the effect of flow rate and inoculation order on plasmid transfer frequency between bacteria in a model rhizosphere system. METHODS AND RESULTS: A physical model system was constructed and used to demonstrate that although flow rate did affect plasmid transfer frequency for an introduced strain, the flow rates necessary for a significant effect on an established population were much higher than typical water flow rates found through soil. Plasmid transfer frequency was highly sensitive to strain inoculation order. CONCLUSION: Flow rate may not have a significant effect on plasmid transfer frequency between established bacterial populations in the rhizosphere. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the current debate over the release and spread of genetically modified organisms into the environment. It also demonstrates that model controlled systems may be used to rapidly obtain initial data about the potential behaviour of microorganisms, prior to more costly and lengthy glasshouse and field trials.

Conjugation, Genetic↗

PubMed2001

Effect of copper on the degradation of phenanthrene by soil micro-organisms.

AIMS: The effect of copper on the degradation by soil micro-organisms of phenanthrene, a polycyclic aromatic hydrocarbon, was investigated. METHODS AND RESULTS: Inert nylon filters were incubated in the soil for 28 days at 25 degrees C. Each filter was inoculated with a soil suspension, phenanthrene (400 ppm), copper (0, 70, 700 or 7000 ppm) and nitrogen/phosphorus sources. The filters were assessed for phenanthrene degradation, microbial respiration and colonization. Phenanthrene degradation proceeded even at toxic copper levels (700/7000 ppm), indicating the presence of phenanthrene-degrading, copper-resistant and/or -tolerant microbes. However, copper at these high levels reduced microbial activity (CO2 evolution). CONCLUSION: High levels of copper caused an incomplete mineralization of phenanthrene and possible accumulation of its metabolites. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of heavy metals in soils could seriously affect the bioremediation of PAH-polluted environments.

Bacteria↗

PubMed2001

Physiological and performance responses to tournament wrestling.

PURPOSE: The purpose of this study was to investigate the physiological and performance responses to a simulated freestyle wrestling tournament after typical weight loss techniques used by amateur wrestlers. METHODS: Twelve Division I collegiate wrestlers (mean +/- SD;19.33 +/- 1.16 yr) lost 6% of total body weight during the week before a simulated, 2-d freestyle wrestling tournament. A battery of tests was performed at baseline and before and immediately after each individual match of the tournament. The test battery included assessment for body composition, reaction/movement time, lower and upper body power and isokinetic strength, and a venous blood sample. RESULTS: Lower body power and upper body isometric strength were significantly reduced as the tournament progressed (P < or = 0.05). Significant elevations in testosterone, cortisol, and lactate were observed after each match (P < or = 0.05). However, there was a significant reduction (P < or = 0.05) in resting testosterone values in the later matches. Norepinephrine increased significantly (P < or = 0.05) after each match, whereas epinephrine increased significantly (P < or = 0.05) after each match except the last match of each day. Plasma osmolality was consistently higher than normal values at all times including baseline, with significant increases observed after each match (P < or = 0.05). CONCLUSIONS: Tournament wrestling augments the physiological and performance decrements of weight loss and its impact is progressive over 2 d of competition. The combined effects of these stresses may ultimately be reflected in a wrestler's ability to maintain physical performance throughout a tournament.

Adolescent↗

PubMed2001

Intranasal vaccination with pneumococcal surface protein A and interleukin-12 augments antibody-mediated opsonization and protective immunity against Streptococcus pneumoniae infection.

Streptococcus pneumoniae is a major pathogen in humans that enters the host primarily through the respiratory tract. Targeting mucosal surfaces directly may therefore be an optimal approach for vaccination to prevent bacterial colonization and invasive disease. We have previously demonstrated the effectiveness of interleukin-12 (IL-12) delivered intransally (i.n.) as an antiviral respiratory adjuvant. In this study, we examined the effects of i.n. IL-12 treatment on induction of protective humoral immunity against S. pneumoniae. Immunization i.n. with pneumococcal surface protein A (PspA) and IL-12 resulted in enhanced lung IL-10 mRNA expression and marked augmentation of respiratory and systemic immunoglobulin G1 (IgG1), IgG2a, and IgA antibody levels compared to those in animals receiving PspA alone. In addition, i.n. vaccination with PspA and IL-12 provided increased protection against nasopharyngeal carriage. Flow cytometric analysis revealed a threefold increase in antibody-mediated, complement-independent opsonic activity in the sera of PspA- and IL-12-treated animals, which was mainly contributed by IgG2a and, to a lesser extent, IgA. Passive transfer of these immune sera conferred complete protection from death upon systemic pneumococcal challenge. These findings demonstrate the effectiveness of combining PspA and IL-12 at mucosal sites to achieve optimal antibody-mediated opsonization and killing of S. pneumoniae.

Adjuvants, Immunologic↗

PubMed2001

Renal hypertension prevents run training modification of cardiomyocyte diastolic Ca2+ regulation in male rats.

The combined effects of endurance run training and renal hypertension on cytosolic Ca2+ concentration ([Ca2+]c) dynamics and Na+-dependent Ca2+ regulation in rat left ventricular cardiomyocytes were examined. Male Fischer 344 rats underwent stenosis of the left renal artery [hypertensive (Ht), n = 18] or a sham operation [normotensive (Nt), n = 20]. One-half of the rats from each group were treadmill trained for >16 wk. Cardiomyocyte fura 2 fluorescence ratio transients were recorded for 7 min during electrical pacing at 0.5 Hz, 2 mM extracellular Ca2+ concentration, and 29 degrees C. The rate of [Ca2+]c decline was not changed by run training in the Nt group but was reduced in the Ht group. At 7 min, cardiomyocytes were exposed to 10 mM caffeine in the absence of Na+ and Ca2+, which triggered sarcoplasmic reticular Ca2+ release and suppressed Ca2+ efflux via Na+/Ca2+ exchanger. External Na+ was then added, and Na+-dependent Ca2+ efflux rate was recorded. Treadmill training significantly enhanced Na+-dependent Ca2+ efflux rate under these conditions in the Nt group but not in the Ht group. These data provide evidence that renal hypertension prevents the normal run training-induced modifications in diastolic [Ca2+]c regulation mechanisms, including Na+/Ca2+ exchanger.

Animals↗

PubMed2001

Impact of CO2 addition to milk on selected analytical testing methods.

The addition of CO2 to raw milk and dairy products controls the growth of psychrotrophic bacteria at refrigeration temperatures. The objective of this study was to determine the effects of dissolved CO2 in milk on the performance of four important routine testing methods: antibiotic residue test, freezing point test, infrared milk component analysis, and alkaline phosphatase test. Raw or pasteurized whole milk was carbonated at <4 degrees C to contain approximately 0 (control), 200, 400, 600, and 1000 ppm of CO2. The addition of CO2 to raw milk up to 1000 ppm had no effect on the performance of the three antibiotic (beta-lactams) residue tests: IDEXX SNAP, Charm II Sequential Tablet, and Delvo-P Ampule. Milk freezing point decreased linearly with increasing concentration of dissolved CO2, from -0.543 degrees H (control) to -0.595 degrees H (1000 ppm). Carbonation to 1000 ppm decreased milk pH (measured at 38 degrees C) from 6.61 (control) to 6.15 (1000 ppm). The effects of CO2 on milk freezing point and pH were reversible upon removal of dissolved CO2. Increased CO2 levels in milk changed the infrared absorption spectrum of milk and caused the corrected lactose readings to decrease and the corrected fat B readings to increase. For the alkaline phosphatase tests, 0 (none), 0.05, 0.1, and 0.2% raw milk were deliberately added to pasteurized milks of six levels of carbonation (0 to 1000 ppm). The addition of CO2 did not influence the ability of Fluorophos, Charm PasLite, and Scharer Modified Rapid tests to differentiate between a pasteurized milk and a pasteurized milk with raw milk contamination.

Alkaline Phosphatase↗

PubMed2000

Substrate Concentration and Plasmid Transfer Frequency between Bacteria in a Model Rhizosphere.

The influence of substrate concentration on plasmid transfer frequency in the rhizosphere was investigated using a physical model employing a hollow fiber membrane instead of a real root. The absolute number of transconjugants produced increased with increasing substrate (glucose) concentration, but the plasmid transfer frequency decreased exponentially with increasing substrate concentration from 4.4 × 10(-3) at 90 μg ml(-1) glucose to 1.35 × 10(-5) at 3600 μg ml(-1) glucose. These results were found to be heavily dependant on donor to recipient ratio and distribution of strains, but independent of initial donor and recipient inoculum density and regime. These observations also show that plasmid transfer frequency is reduced at high substrate concentrations, which suggests that plasmid transfer is either stimulated when growth limiting nutrient is scarce or inhibited when it is abundant.

Journal Article↗

PubMed2000

Effect of biocontrol strains of Trichoderma on plant growth, Pythium ultimum polulations, soil microbial communities and soil enzyme activities.

Five strains of Trichoderma with known biocontrol activities were assessed for their effect upon pea growth and their antagonistic activity against large Pythium ultimum inocula. The effect of Trichoderma inocula upon the indigenous soil microflora and soil enzyme activities in the presence and absence of Pythium is assessed. In the absence of Pythium, Trichoderma strain N47 significantly increased the wet shoot weight by 15% but did not significantly affect the dry weight, whilst strains T4 and N47 significantly increased the root weights by 22% and 80%) respectively. Strains TH1 and N47 resulted in significantly greater root lengths. Pythium inoculation significantly reduced the root length and the number of lateral roots and nodules, and significantly increased the root and rhizosphere soil fungal populations. Pythium inoculation significantly reduced the plant wet and dry shoot weights and significantly increased the wet and the dry shoot/root ratio. All the Trichoderma strains reduced the number of lesions caused by Pythium and increased the number of lateral roots. The effect of the Pythium on emergence and shoot growth was significantly reduced by all the Trichoderma strains except strain To10. Inoculation with Trichoderma strains TH1 and T4 resulted in significantly greater wet root weights (62% and 57%, respectively) in the presence of Pythium compared to the Pythium control. Strain N47 significantly increased the shoot/root ratio compared to the Pythium control. Inoculation with Trichoderma strains T4, T12 and N47 significantly reduced Pythium populations. Pythium increased the activity of C, N and P cycle enzymes, whilst four Trichoderma strains reduced this effect, indicating reduced plant damage and C leakage. Overall, strains T4 and N47 had the greatest beneficial characteristics, as both these strains improved plant growth in the absence of Pythium and reduced plant damage in the presence of Pythium. The dual properties of these strains improve the commercial application, giving them an advantage over single action inocula, especially in the absence of plant pathogens.

Acetylglucosaminidase↗

PubMed2000

For the love of the children: the coming out process for lesbian and gay parents and stepparents.

This research investigated the coming out decision and process for 23 lesbian and gay custodial stepfamilies. We argue that lesbian and gay stepfamilies represent a unique type of family, distinct from heterosexual stepfamilies and from lesbian and gay families who have children within the context of a lesbian or gay relationship. The coming out process is one developmental challenge that distinguishes lesbian and gay stepfamilies from these other types. Through interviews with both lesbian and gay parents and stepparents we explored their coming out process to significant others: the children, families of origin and ex-spouses. We discuss those factors influencing the decision and the consequences that developed in light of these decisions. Findings show that the coming out process for lesbian and gay co-parents is a flexible and familial one, primarily influenced by and centered around the needs of the children.

Decision Making↗

PubMed2000

Considerations of family structure and gender composition: the lesbian and gay stepfamily.

Lesbian and gay stepfamilies are unique family forms which must be investigated as such. This paper explores the similarities and dissimilarities between heterosexual stepfamilies and lesbian/gay stepfamilies, arguing that similarity of structure is impacted by gender composition. Utilizing face-to-face and telephone interviews with biological and stepparents in 23 lesbian and gay stepfamilies, the results show that while lesbian and gay stepfamilies share some challenges and strengths with heterosexual stepfamilies, they also evidence a unique and flexible adaptation to becoming a family. The paper is aimed at delineating future areas for lesbian and gay stepfamily research.

Family↗

PubMed2000

Progression of radiographic joint erosion during low dose corticosteroid treatment of rheumatoid arthritis.

OBJECTIVE: The reported prevention of joint damage during treatment with prednisolone 7.5 mg daily in patients with early rheumatoid arthritis (RA)3 may have important implications for management of RA. We evaluated this observation in another patient population. METHODS: Radiographic progression rates in paired hand radiographs were analyzed in 824 patients with RA who participated in a 3 year prospective, randomized clinical trial comparing the nonsteroidal antiinflammatory drugs (NSAID) etodolac (150 or 500 mg bid) and ibuprofen (600 mg qid). Disease modifying antirheumatic drugs (DMARD) were not permitted. Prednisone < or=5 mg daily was continued by 197 patients (mean dose 4.37 mg daily) who had started prednisone therapy at least 6 mo before study entry, but new prednisone starts were not allowed. Standardized hand/wrist radiographs were done yearly and at dropout; joint erosion and narrowing scores of 3 readers were averaged and progression rates were compared. RESULTS: Mean duration of RA was 3.6 years (range 1-7); patients' ages were 21-78 years; 71% were women. Among the 824 patients, those taking prednisone were more likely to have had previous DMARD, and at study entry had higher radiographic scores for joint erosion and joint space narrowing and slightly higher swollen joint counts, C-reactive protein values, and rheumatoid factor titers than those not taking prednisone. However, for the subgroup of 252 patients with RA duration of 12-24 months, prestudy radiographic scores were not different in those taking or not taking prednisone. The mean (+/-SD) monthly rate of increase in erosion scores was 0.228 +/-0.37 for the prednisone patients and 0.206+/-0.35 for patients not taking prednisone (p = 0.994 by ANCOVA). The subgroup with 12 to 24 months' disease duration at entry also showed no significant effect of prednisone treatment on erosion progression. CONCLUSION: Clinically indicated low dose prednisone did not prevent progressive radiographic damage in 197 NSAID treated patients whose physicians had initiated < or =5 mg daily before study entry. The risk/benefit ratio of chronic low dose prednisone in early RA remains uncertain.

Adrenal Cortex Hormones↗

PubMed1999

Management of blunt pancreatic injury in children.

BACKGROUND AND METHODS: Controversy persists regarding the management of pancreatic transection. Over the past 10 years, 51 patients admitted to the Children's Hospital of Pittsburgh sustained blunt pancreatic injuries. We reviewed their medical records to clarify the optimal management strategy and to define distinguishing characteristics, if any, of patients with pancreatic transection. RESULTS: Patients who sustained pancreatic transection had a significantly higher Injury Severity Score, length of stay, serum amylase, and serum lipase, than those patients who sustained pancreatic contusion. Patients who underwent laparotomy within 48 hours of injury for pancreatic transection had a significantly shorter length of stay than those who underwent laparotomy more than 48 hours after injury. CONCLUSION: Serum amylase greater than 200 and serum lipase greater than 1,800 may be useful clinical markers for major pancreatic ductal injury when combined with physical examination. Early operative intervention for pancreatic transection results in shorter length of stay and fewer complications.

Age Factors↗

PubMed1999

Chronic run training suppresses alpha-adrenergic response of rat cardiomyocytes and isovolumic left ventricle.

The effects of endurance run training on alpha-adrenergic responsiveness of rat left ventricle (LV) were examined in cardiomyocytes and isovolumic LV. Female Sprague-Dawley rats were sedentary (Sed) or trained (Tr) for >20 wk by treadmill running. Cardiomyocyte shortening and fura 2 fluorescence ratio were recorded before and during 5-min exposure to 5 microM phenylephrine (PE) while paced at 0.5 Hz in 2 mM extracellular Ca2+ concentration at 29 degrees C. Cardiomyocyte shortening and shortening velocity increased with PE, and these effects were more pronounced in the Sed group. The rate of cytosolic Ca2+ concentration removal was reduced by PE in the Sed cardiomyocytes, but was unaffected in the Tr. Isovolumic LV pressure was recorded immediately before and during 5-min perfusion with 5 microM PE during pacing at 280 beats/min and 37 degrees C, and positive inotropy due to PE was more pronounced in the Sed than in the Tr. These data demonstrated that the effects of alpha-adrenergic stimulation on myocardial positive inotropy and calcium regulation were reduced in this rat model of run training at both the cellular and whole organ levels.

Adrenergic alpha-Agonists↗

PubMed1999

Effects of chronic run training on Na+-dependent Ca2+ efflux from rat left ventricular myocytes.

The effects of endurance run training on Na+-dependent Ca2+ regulation in rat left ventricular myocytes were examined. Myocytes were isolated from sedentary and trained rats and loaded with fura 2. Contractile dynamics and fluorescence ratio transients were recorded during electrical pacing at 0.5 Hz, 2 mM extracellular Ca2+ concentration, and 29 degreesC. Resting and peak cytosolic Ca2+ concentration ([Ca2+]c) did not change with exercise training. However, resting and peak [Ca2+]c increased significantly in both groups during 5 min of continuous pacing, although diastolic [Ca2+]c in the trained group was less susceptible to this elevation of intracellular Ca2+. Run training also significantly reduced the rate of [Ca2+]c decay during relaxation. Myocytes were then exposed to 10 mM caffeine in the absence of external Na+ or Ca2+ to trigger sarcoplasmic reticular Ca2+ release and to suppress cellular Ca2+ efflux. This maneuver elicited an elevated steady-state [Ca2+]c. External Na+ was then added, and the rate of [Ca2+]c clearance was determined. Run training significantly reduced the rate of Na+-dependent clearance of [Ca2+]c during the caffeine-induced contractures. These data demonstrate that the removal of cytosolic Ca2+ was depressed with exercise training under these experimental conditions and may be specifically reflective of a training-induced decrease in the rate of cytosolic Ca2+ removal via Na+/Ca2+ exchange and/or in the amount of Ca2+ moved across the sarcolemma during a contraction.

Algorithms↗

PubMed1999

Twice daily suckling but not milking with calf presence prolongs postpartum anovulation.

Two experiments were conducted to determine whether milking beef cows two or five times daily in the presence or absence of their own nonsuckling calves would alter postpartum interval to first ovulation. Multiparous Angus x Hereford cow-calf pairs were assigned randomly between 13 and 18 d postpartum to treatments for 4 wk. In Exp. 1, pairs were assigned to six treatments: 1) calf was weaned permanently from its dam (CW; n = 9); 2) same as CW, but dam was milked twice daily (CW+2xM; n = 9); 3) calf was present continuously with its dam but restricted from contact with the udder (CR; n = 9); 4) same as CR, but dam was milked twice daily (CR+2xM; n = 9); 5) same as CR, but calf was allowed to suckle twice daily (CR+2xS; n = 8); and 6) calf was present continuously with its dam and suckled ad libitum (CP; n = 9). The interval from onset of treatments to first postpartum ovulation was shorter (P<.05) in the CW (14.1+/-3.1 d), CR (14.2+/-3.1 d), CW+2xM (13.0+/-3.1 d), and CR+2xM (17.2+/-3.1 d) than in the CP (34.7+/-3.1 d) and CR+2xS (33.9+/-3.3 d) treatments. Daily milk yield during treatment was greater (P<.01) for CR+2xM cows (7.1+/-.6 kg) than for CW+2xM cows (3.5+/-.6 kg). In Exp. 2, cow-calf pairs were assigned to three treatments: 1) CR+2xM (n = 10); 2) same as CR+2xM but cows were milked five times daily (CR+5xM; n = 10); or 3) CP (n = 10). The interval to first postpartum ovulation was shorter (P<.05) in the CR+2xM (23.6+/-3.5 d) and CR+5xM (26.1+/-3.7 d) treatments than in the CP (37.7+/-3.7 d) treatment. Daily milk yield during treatment was greater (P<.05) for CR+5xM cows (7.7+/-.6 kg) than for CR+2xM cows (6.4+/-.6 kg) by 17%. We conclude that suckling twice daily was sufficient to prolong postpartum anestrus as much as suckling ad libitum. Furthermore, milk removal by suckling, but not by milking two or five times daily, even in the presence of the cow's own nonsuckling calf, is essential to prolong postpartum anovulation.

Animals↗

PubMed1999

Suckling reinitiated milk secretion in beef cows after an early postpartum hiatus of milking or suckling.

We determined whether milk secretion in beef cows could be reinitiated by renewed suckling after a hiatus from milking or suckling. Fifty-three Angus x Hereford cows were suckled ad libitum by their own calves for 13 to 18 d postpartum and then assigned to treatments for 4 wk in which cows were 1) neither milked nor suckled (weaned; n = 18), 2) milked 2 x daily (milked; n = 18), or 3) suckled by their own calves (suckled; n = 17). Thereafter, all calves (including earlier weaned calves) suckled their own dams until permanent weaning at 203 d of age, except when their dams were milked once after receiving (i.m.) 40 IU of oxytocin at reinitiation of suckling (0 wk) and again 1 and 5 wk later. Prolactin was increased in milked and suckled cows during 20 min after milking or suckling at the termination of treatments (0 wk). Concentrations of insulin-like growth factor-I were greater for weaned than suckled cows; milked cows had intermediate concentrations. At 0 wk, milk yield was greater for suckled than milked or weaned treatment cows. After 1 wk of renewed suckling, milk secretion of weaned treatment cows increased, and by 5 wk, composition of milk was normal, but yield was still reduced. We concluded that milk secretion was renewed by suckling in early postpartum cows after they were neither suckled nor milked for 4 wk.

Animals↗

PubMed1999

Effects of insulin and amino acids on milk protein concentration and yield from dairy cows.

Our study investigated the effect of insulin on the regulation of milk protein synthesis in well-fed cows (n = 4) with or without additional amino acids (AA). The design was a two-way crossed factorial with two 12-d periods involving abomasal infusions of either water or a mixture of casein (500 g/d) plus branched-chain AA (88 g/d). During the last 4 d of each period a hyperinsulinemic-euglycemic clamp was performed; insulin was infused at 1.0 microgram.kg of BW-1.h-1 to increase circulating levels fourfold, and euglycemia was maintained by infusion of glucose. Cows were fed a diet formulated to exceed requirements for metabolizable energy and protein. During abomasal water infusion, the insulin clamp increased milk protein yields by 15% (+128 g/d); when combined with abomasal infusion of casein plus branched-chain AA, milk protein yield was increased by 25% (+213 g/d). These increases resulted from equivalent increases in milk protein concentration and milk yield. Concentrations of casein and whey proteins in milk were increased by insulin clamp treatments; however, there were no major changes in the relative proportions of individual casein and whey proteins. Plasma concentrations of essential AA were reduced (-33%) during the insulin clamp treatments; effects were most dramatic for the branched-chain AA (-41%) and their keto acids (-45%). Results confirm the important regulatory role of the endocrine system in milk protein synthesis and demonstrate this potential to produce milk protein is not fully expressed.

Abomasum↗

PubMed1998

Luteal function and estrus in peripubertal beef heifers treated with an intravaginal progesterone releasing device with or without a subsequent injection of estradiol.

The objectives of this experiment were to determine if treatment of beef heifers with progesterone (P4) using an intravaginal device alone or in combination with estradiol benzoate (EB) would induce estrus and cause development of corpora lutea (CL) with a typical life span. Peripubertal heifers (n = 311) were used when about 40% of the heifers had a functional CL. The heifers were assigned to receive one of the following treatments on Day 0: 1) a sham device for 7 d (C, n = 108); 2) an intravaginal device containing P4 for 7 d (P, n = 102); or 3) an intravaginal device containing P4 for 7 d plus an injection of 1 mg EB 24 to 30 h after device removal (PE, n = 101). Serum concentrations of P4 were determined on Days -7, 0, 8, 15 and 22. Weight and age of the heifers at the start of the trial averaged 292 +/- 45 kg and 365 +/- 38 d, respectively. A greater (P < 0.0001) proportion of the heifers from the PE than P group was in standing estrus (81 vs 37%) and formed normal CL (68 vs 44%) after device removal. Of the heifers exhibiting estrus, a greater (P < 0.05) proportion of PE (94%) than P (80%) heifers was active 1 to 3 d after implant removal. Short-term progesterone treatment increased the proportion of heifers in estrus and those forming normal CL, and adding EB to the progesterone treatment further enhanced these responses.

Administration, Intravaginal↗