Biomedical subjects

L Hoffman-Goetz

Publications and source records attributed to L Hoffman-Goetz.

At least 73 records · Page 4Linked to original sources

PubMed1989

Exercise stress alters murine lymphocyte subset distribution in spleen, lymph nodes and thymus.

Our previous work indicated that exercise stress in mice was associated with reduced splenic lymphocyte proliferation to T cell mitogens. The purpose of this study was to determine the effect of acute exercise stress and exercise training on the phenotype distribution of murine lymphocytes in the spleen, lymph nodes and thymus. In mice given an exhaustive bout of treadmill exercise, the percentage of Thy 1.2 and Lyt2 antigen bearing cells decreased in the thymus, but the percentage of L3T4-positive cells did not change significantly. Acute exercise did not alter the percentage of Thy1.2, L3T4 or Lyt2-positive cells in the secondary lymphoid compartments (nodes, spleen). By contrast, in mice given a chronic exercise training programme (8 weeks duration; 30 m/min, 8 degrees slope, 30 min/session, 5 daily sessions/week) followed by a 72 h rest period, the percentage of L3T4-positive cells increased by 53% in the spleen, 19% in the lymph nodes and 29% in the thymus compared with sedentary controls; no parallel increase in the percentage of Thy1.2 antigen bearing cells was observed. These results suggest that the effect of exercise on the frequencies of lymphocyte subpopulations in murine lymphoid compartments is dependent upon the chronicity of the stress and probably on the accompanying physiological adaptations to the stress.

Animals↗

PubMed1988

Splenic immune responses following treadmill exercise in mice.

The in vitro proliferation response to lipopolysaccharide and pokeweek mitogen by splenic lymphocytes and the effect on the total splenic lymphocyte number were examined in C57BL/6J mice following an 8-week treadmill training program (30 m/min, 8 degrees slope, 30 min/day, 5 times/week) and after a single bout of exhaustive exercise (50% stepwise increases in final running speed for 10-min intervals). Plasma corticosterone levels were also measured to evaluate whether changes in adrenocortical activation were associated with exercise-induced immunomodulation. In comparison to sedentary controls, trained mice had an increase of 35% in succinate dehydrogenase activity per unit of protein in the quadriceps femoris muscle. Trained mice showed an increase in splenic lymphocyte proliferation to both mitogens which was evident 72 h after completion of the final training session, relative to sedentary controls. Immediately following exercise, however, lymphocyte proliferative responses were depressed compared with the training and the control values. The exercise regimen resulted in a reduction in total number of mononuclear cells per spleen. Changes in plasma corticosterone levels after exercise were not clearly associated with immunodepression or immunoenhancement of splenic lymphocyte mitogenesis. Taken together, the data suggest that moderate endurance training augments splenic B lymphocyte mitogenesis and further, that the immediate effects of exercise on splenic immune function vary with the duration and intensity of the work.

Animals↗

PubMed1987

Differential early rearing affects response to overfeeding in B6D2F2 mice.

Male and female B6D2F2 mice, reared in small (Sm = 4), medium (Md = 8) and large (Lg = 12) litters, were maintained on high-fat, high-carbohydrate (EXP) or chow (CH) diets beginning at 14 weeks. EXP mice consumed more calories and gained more weight than CH mice; these effects were greatest in the Sm animals. Each sex responded similarly. Caloric efficiency was highest in the Sm EXP and male animals. Total body fat in males showed that Sm greater than Md greater than Lg and EXP greater than CH. The thermogenic capacity was measured by total oxygen consumption and body temperature response during acute cold stress, and protein content and cytochrome c oxidase activity in interscapular brown adipose tissue (1BAT). Sm mice had a smaller decrease in temperature and consumed less oxygen per gram body weight than Lg, suggestive of a contributing role of increased insulation. When oxygen consumption was expressed as a function of body weight0.75, EXP greater than CH, but there were no other significant dietary effects. Neither litter size nor diet appeared to affect protein content or cytochrome c oxidase activity in 1BAT. These results show that early rearing experience effects both behavioural and physiological variables associated with the maintenance of adult body weight in mice, but these effects do not appear to be mediated through 1BAT.

Animals↗

PubMed1986

The effect of cold acclimation and exercise training on cold tolerance in aged C57BL/6J mice.

We investigated whether intermittent cold acclimation and low intensity exercise training, two interventions known to improve thermoregulatory function in young rodents, enhanced cold tolerance in aged C57BL/6J mice. Mice, aged 18 to 20 months, were randomly assigned to four treatment conditions: (a) intermittent cold acclimation (CA) (50 min per day, 5 times per week for 3 weeks at 5 degrees C), (b) submaximal treadmill exercise (EX) (15 m min-1 for 30 min, 5 times per week for 8 weeks, (c) sequential treatment of CA + EX, and (d) control group. Mice were exposed to a 3-hr cold stress test (15 degrees C) prior to and following treatment. CA aged mice maintained normothermia and demonstrated significant increases in oxygen consumption and brown adipose tissue protein concentration compared with controls; enhanced cold tolerance was probably due to increased utilization of nonshivering thermogenesis. EX aged mice had elevated O2 consumption and increased skeletal muscle enzyme activity compared with controls; however, cold tolerance was not enhanced compared with CA mice. The data suggest that intermittent CA effectively reduces hypothermia during cold challenge in aged mice.

Acclimatization↗

PubMed1986

Modulation of cellular immunity in malnutrition: effect of interleukin 1 on suppressor T cell activity.

T-lymphocyte mitogenesis is impaired in protein-energy malnutrition. The effect of interleukin 1 (IL-1) on the augmentation of suppressor cell activity during concanavalin A-induced lymphocyte proliferation was measured using IL-1 and lymphocytes from protein malnourished and control rabbits. Addition of IL-1 to lymphocyte cultures from control donors enhanced the suppression of fresh lymphocytes to phytohaemagglutinin (PHA). Addition of IL-1 to lymphocyte cultures from malnourished donors abrograted the suppressor cell activity. Isoelectric focusing showed the presence of a protein band with a pI of about 7.0 in the IL-1 supernatants from protein malnourished and control donors. The results suggest that severe protein malnutrition alters the ability of T-lymphocytes to respond appropriately to IL-1 rather than simply affecting synthesis of this monokine.

Animals↗

PubMed1986

Monocyte factors modulate in vitro T-lymphocyte mitogenesis in protein malnutrition.

This study investigated changes in T-lymphocyte mitogenesis and immunoregulatory cytokines during protein malnutrition. In vitro T cell response to concanavalin A was compared among protein deprived (PD), energy restricted pair fed control (PF), and ad libitum control (C) rabbits. Cell cultures were supplemented with crude monocyte supernatants (CMS) from PD, PF or C animals at either 1% or 8% final concentration in culture. Prostaglandin E2 (PGE2) concentration of unstimulated or stimulated lymphocyte culture supernatants and CMS was determined. Lymphocyte cultures from PD, PF and C animals had enhanced 3H-thymidine incorporation when supplemented with C and/or PF derived CMS. Addition of 8% CMS from PD rabbits inhibited proliferation below levels observed in mitogen-only stimulated groups in all cultures. At the 1% concentration, inhibition was seen in PD and C derived cells cultures and modest enhancement was seen in PF cultures. PGE2 concentration in supernatants from stimulated and unstimulated lymphocyte cultures from PD rabbits were higher than in C and PF cell cultures. These results suggest (a) that under appropriate culture conditions lymphocytes from PD donors are capable of enhanced proliferation and (b) that depressed T cell mitogenesis observed in protein malnutrition may reflect alterations in immunoregulatory signals. The role of interleukin 1 (IL-1) and PGE2 in the modulation of this response is discussed.

Animals↗

PubMed1986

Chronic exercise stress in mice depresses splenic T lymphocyte mitogenesis in vitro.

This study investigated changes in functional response to splenic T lymphocytes of mitogens following acute and chronic exposure to endurance exercise. Splenic T cell response in vitro to concanavalin A (Con A) and the total number of lymphocytes per spleen were compared between mice assigned to the following treatment conditions: (a) exercise training (EX) by treadmill running (28 m/min, 8 degrees slope for 30 min, 5 times per week for 4 weeks preceded by 2 weeks of endurance build-up), (b) exercise training as above followed by a single, acute bout of exercise to exhaustion (EX + AC) (35 m/min, 8 degrees slope, 30 min to 2 h duration) (c) exposure to the novel environment for 6 weeks without exercise (control), and exposure to the novel environment as in (c) followed by a single, acute bout of exercise to exhaustion. Treadmill running for 6 weeks significantly enhanced succinate dehydrogenase activity in skeletal muscle compared to the sedentary, control condition, and was broadly interpreted as indicative of a training effect. EX mice had significantly reduced splenic lymphocyte proliferative responses to optimal and supraoptimal concentrations of Con A compared with control animals. Incorporation of [3H]thymidine into splenic lymphocytes from EX + AC mice was the most markedly depressed. Total number of lymphocytes per spleen was significantly lower in EX compared with control mice. These results suggests that chronic exercise challenge in mice is associated with T lymphocyte hyporesponsiveness in the secondary lymphoid organs, such as the spleen.

Animals↗

PubMed1985

Fever and survival in aged mice after endotoxin challenge.

Male C57BL/6 mice of 12, 19, and 24 months of age received injections of low (25 micrograms 100 g-1 body weight) or high (50 micrograms 100 g-1 body weight) doses of Salmonella typhosa endotoxin and were exposed to ambient temperatures below (24 degrees C) or within (30 degrees C) the thermoneutral zone. Old mice (19 and 24 months) developed initial fevers followed by hypothermia in response to endotoxin challenge at 24 degrees C, irrespective of dose; 12-month-old-mice became hypothermic at 24 degrees C following injection of the high dose of endotoxin only. At 30 degrees C, 12- and 19-month-old mice developed and maintained fever over 4 hr in response to endotoxin compared with the 24-month-old mice who were unable to maintain fevers. Logistic regression analysis showed that age, ambient temperature, and body temperature responses were significant predictors of survival outcome in endotoxin-treated mice; of these, age and ambient temperature had the strongest effects.

Aging↗

PubMed1984

Body temperature responses of aged mice to ambient temperature and humidity stress.

Male C57BL/6 mice aged 6 to 7 months, 13 to 14 months, and 19 to 20 months were acutely exposed to four ambient temperature (15 degrees C, 20 degrees C, 30 degrees C, 35 degrees C) and two relative humidity (50% rh, 80% rh) conditions. Three-hour average rectal temperatures were compared across age groups and environmental conditions. At the two temperature extremes of 15 degrees C and 35 degrees C, there was a very marked age-associated hypothermia and hyperthermia, respectively. This hypothermic response was maintained by the 19 to 20-month-old mice during exposure to 20 degrees C and thermoneutrality (30 degrees C). At any given ambient temperature, relative humidity had no effect on thermoregulatory function in the oldest mice, whereas the 6 to 7-month- and 13 to 14-month-old mice were sensitive to the effects of humidity at 15 degrees C and 20 degrees C.

Aging↗

PubMed1983

Effect of treadmill exercise on food intake and body weight in lean and obese rats.

Body weight and food intake of lean and obese, male and female Osborne-Mendel rats following treadmill exercise were compared. Rats were assigned, separately by sex, to one of three diet groups; Group 1 was fed a low fat (10%) diet throughout the study, Group 2 was fed a high fat (55%) diet for 16 weeks and then switched to the low fat diet 1 week prior to exercise, and Group 3 was fed the high fat diet throughout the study. To control for differences in work output between the leanest and heaviest animals, exercise intensity was adjusted across groups such that all exercised rats had equivalent energy expenditure. After a 3 day training period, the exercise was successively increased over 8 days until a work output of 374.9J was reached. Relative to their respective controls, obese exercised males showed a reduction in body weight but no change in food intake. In contrast, exercised females showed no change in body weight or food intake, regardless of dietary condition.

Animals↗

PubMed1983

Effect of protein deficiency on endogenous pyrogen-mediated acute phase protein responses.

Endogenous pyrogen (EP) is known to trigger a rise in the plasma concentrations of various acute phase reactant proteins. This study describes the effects of chronic protein deficiency in rabbits on EP-mediated changes in the plasma concentrations of fibrinogen, albumin, and alpha 2-macroglobulin. Injection (i.v.) of EP from healthy donors into protein-deprived rabbits produced a smaller rise in plasma fibrinogen and alpha 2-macroglobulin, and a smaller fall in plasma albumin than injection of EP into controls. Injection of EP, obtained from malnourished donors, into healthy rabbits also resulted in an attenuation of the acute phase protein response. These data are consistent with the hypothesis that EP activity is influenced by the nutritional status of both the donor and recipient of EP.

Animals↗

PubMed1982

Protein deficiency and endogenous pyrogen fever.

Blood monocytes have been shown to be a major source of endogenous pyrogen (EP), the protein mediator of fever. This study describes the effects of chronic dietary protein deficiency in rabbits on the in vitro production of EP by monocytes, the time course for the dietary effects on EP production, and the possible role for serum factors in the modification of EP production and (or) development of fever. EP harvested from rabbits on a protein-free diet for 4 weeks induced normal fevers when injected i.v. into recipient animals; EP produced from the protein-deprived rabbits after 6 and 8 weeks did not elicit fevers when bioassayed. Injection of EP supernatants derived from protein-deprived rabbits and containing standard protein serum resulted in less aberrant temperature responses than injection of EP supernatants containing sera from protein-deprived rabbits. These results suggest that: (i) the production of EP by rabbit blood monocytes is sensitive to dietary protein status, (ii) the effect of protein deficiency on EP production is a threshold phenomenon, and (iii) factors present in sera of protein-deprived rabbits may modify EP-induced fever.

Animals↗

PubMed1981

Febrile and plasma iron responses of rabbits injected with endogenous pyrogen from malnourished patients.

The ability of human endogenous pyrogen (EP) harvested from malnourished patients (marasmic or kwashiorkor-like) to induce fever and a simultaneous hypoferremia in rabbits is described. Human peripheral blood leukocytes were obtained from malnourished adult patients before total parenteral nutrition support, and after 1 and 7 days on this therapeutic regime; the leukocytes were stimulated to produce EP in vitro and EP was injected into each rabbit. EP obtained from the leukocytes of patients with predominant protein deprivation syndromes (kwashiorkor) before nutritional support produced an attenuated fever (0.23 degrees C over 4 h) and a relatively unchanged plasma iron concentration (delta Fe = -15 microgram/100 ml over 4 h) in the rabbits. When EP was harvested from these same patients after 7 days of nutritional support therapy and was injected into rabbits, normal 4 h fevers (1.10 degrees C) and reduction in plasma iron levels (delta Fe = -97 micrograms/100 ml) occurred in the rabbits. Human EP obtained from patients with marasmus (predominant calorie deprivation syndromes) produced relatively normal fevers and changes in plasma iron levels in the rabbits, regardless of whether the samples were taken pre-total parenteral nutrition or after 1 and 7 days of total parenteral nutrition. These observations suggest that the synthesis of endogenous pyrogen by human peripheral leukocytes is sensitive to the availability of key substrates and that nutritional support therapy restores the capacity of these cells to produce EP in vitro.

Adult↗

PubMed1979

Protein deficiency: its effects on body temperature in health and disease states.

Little is known about the effects of protein malnutrition on the ability to regulate body temperature during health and disease. To investigate this area, we placed young rabbits on a low-protein diet and recorded their body temperatures. There were no differences between the protein-deprived and control animals concerning their abilities to maintain constant body temperatures during exposure to low (5 C, 10 C) and thermoneutral ambient temperature (20 C). In a warm ambient temperature (30 C) the protein-deprived animals were actually better able to maintain a lower body temperature. Injections with heat killed bacteria led to little or no fever in the protein-deprived group. However, intravenous injections of endogenous pyrogen, a protein mediator of fever, resulted in fevers virtually identical to that attained in control animals. These data indicate that the attenuated febrile response to bacterial injection during protein deprivation may be due to a diminished production of endogenous pyrogen, and not to some alteration in the central nervous system sensitivity to pyrogens.

Animals↗

PubMed1979

Protein deprivation: its effects on fever and plasma iron during bacterial infection in rabbits.

1. The effects of chronic dietary protein deprivation on fever and host plasma iron reduction in bacterially infected rabbits (Oryctolagus cuniculus) were investigated. 2. Injection with Pasteurella multocida, a Gram-negative bacterium pathogenic to rabbits, led to an attenuated 24 hr fever in the protein-deprived rabbits (0.26 degrees C) compared with the 24 hr fever in the control rabbits (1.43 degrees C). 3. Plasma iron concentration remained relatively high in the protein-deprived rabbits as measured 24 hr after injection with bacteria. Total iron binding capacity did not change in the protein-deprived rabbits as measured 24 hr after injection with bacteria. 4. Inoculation of the rabbits with endogenous pyrogen from donor rabbits resulted in fever and reduction in plasma iron concentration that was of equal magnitude in the protein-deprived and control rabbits. 5. There were no differences in the concentration of total circulating leukocytes or in the differential count between the protein-deprived and control rabbits before and 24 hr after injection with bacteria. 6. These data support the hypothesis that chronic protein deprivation in rabbits results in a diminished synthesis or release, or both, of endogenous pyrogen from circulating leukocytic phagocytes, resulting in an attenuated fever and a relative hyperferremia during infection.

Animals↗

PubMedDate not supplied

Cancer experiences of African-American women as portrayed in popular mass magazines.

Popular magazines provide opportunities for teachable moments about cancer prevention and control to broad segments of the population. The purpose of this study was to evaluate attitudes and beliefs about cancer as presented in magazine cancer stories with a predominant readership of African-American women. Information was collected on full length cancer stories in Jet, Ebony and Essence from 1987 to 1995. There were 11 personal stories about cancer impact on women in the magazine issues over 9 years. Five themes emerged: religiosity, cancer fatalism, quality of life after diagnosis, interactions with medical personnel, and treatment choices. Within each theme area, specific subthemes were identified. Within religiosity, subthemes included the importance of faith, God's role, and the challenge to the spirit of a cancer diagnosis. Negative interactions with the medical system were described in 45% (5/11) of the stories. Quality of life emerged as an important issue in the cancer stories with death and dying, and pain or side-effects of treatment appearing in 64% (7/11) of the narratives. These results suggest that narratives in magazines with predominant readership among African-American women emphasize religious beliefs in cancer survival and present mixed attitudes towards European-American medical institutions. Mass media contributes to that discourse which shapes women's attitudes about survival from cancer.

Adaptation, Psychological↗

PubMedDate not supplied

Effect of 17beta-estradiol and voluntary exercise on lymphocyte apoptosis in mice.

During the perimenopause, women may begin estrogen replacement therapy (ERT) and physical activity programs to reduce the symptoms of the climacteric. High-intensity exercise increases lymphocyte apoptosis, and estrogen is also known to have immune modulatory effects. The present study determined whether (1) estrogen exposure in vivo, and (2) low-intensity, voluntary exercise affect thymic and splenic lymphocyte apoptosis in adult female mice. 'Middle-aged' (>1 year), ovarian-intact female B6D2F(1) mice were implanted with 17beta-estradiol (E) pellets (L: 3 microg/day or H: 12 microg/day) or placebo (P: 0 microg/day). Mice were given 1 week to recover from implantation surgery after which they were randomized to wheel-running or no-wheel-running conditions. Twenty one days later, mice were sacrificed and thymus and spleen removed for determination of percent apoptosis and percent necrosis by flow cytometry, serum E levels by RIA, and tissue and body weights. Estrogen-treated, ovarian-intact mice accumulated less cumulative wheel-running activity than mice implanted with placebo (P<.001). E exposure was associated with lighter thymuses (P<.05), higher thymocyte apoptosis (P<.001), and higher serum E levels (P<.001), effects which were not modified by voluntary exercise. In contrast, splenocyte apoptosis and spleen weights did not differ by estrogen treatment or exercise. The results suggest that in vivo exposure to supplemental estrogen is associated with greater spontaneous apoptosis of thymocytes and reduced thymus weights in older ovarian-intact mice. The clinical significance for thymic (cellular) immunity in perimenopausal women given HRT remains to be determined.

Age Factors↗

PubMedDate not supplied

Effect of estradiol and exercise on lymphocyte proliferation responses in female mice.

Many North American women are encouraged to take estrogen replacement therapy and to begin (or continue) physical activity during the postmenopausal years. This study investigated the effect of estradiol exposure and physical exercise on lymphocyte proliferation responses to T and B cell mitogens in female mice. Sixty C57BL/6 mice were randomized to hormone and exercise treatment conditions: hormone treatment consisted of estradiol in vivo (71.4 microg estradiol per day for 21 days) or placebo pellet following bilateral ovariectomy, or surgical sham (mice were not ovariectomized). Exercise consisted of a single forced treadmill run (26 m/min, 6 degrees slope, 90 min) or a sedentary control condition. Outcomes were thymic and splenic lymphocyte proliferation responses to the mitogens concanavalin A (ConA, 1.0 and 5.0 microg/mL concentrations) and lipopolysaccharide (LPS, 0.5, 1.0, and 2.0 microg/mL concentrations). In the thymus, there was a significant reduction of proliferation to ConA in the Ovx + E2 animals relative to the other conditions at both concentrations of mitogen. At 1.0 microg/mL concentration, there was a significant interaction of hormone and exercise treatments. Sham (control) mice given exercise had a higher proliferation response relative to sedentary counterparts, whereas E2 mice did not differ in proliferation responses, irrespective of exercise condition. In the spleen, exposure to high concentrations of estradiol was associated with reduced proliferation responses to both mitogens; there were, however, no main or interaction effects of exercise. These results suggest that high levels of estradiol exposure following ovariectomy in mice significantly reduces lymphocyte blastogenesis responses, and that thymic immunomodulation after acute exercise is masked by the hormonal effect.

Animals↗