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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an attempt to determine whether the seminiferous tubular atrophy of the cryptorchid testis is preventable by early surgical correction of the cryptorchid state, aberrantly developed gubernacula destined to result in a cryptorchid testis in the Long-Evans cryptorchid (LE/ORL) rat were surgically reimplanted to the bottom of the scrotum on day 10 to 12 of age. Testis descent was monitored and the changes in testicular histology and in the volumes of the seminiferous tubules and Leydig cells were examined at day 60. As expected, normal testis descent occurred on or about day 25. Compared to untreated undescended testes at day 60, relative seminiferous tubular volumes (volume: % +/- SEM) were significantly increased by early surgical reimplantation of the gubemacula (89 +/- 1 vs. 66 +/- 3; P < 0.01). Absolute seminiferous tubular volumes (microliter +/- SEM) were also significantly increased by early surgical intervention when compared to undescended nontreated testes (893 +/- 27 vs. 170 +/- 12; P < 0.01). The testes of the surgically corrected cryptorchid animals were similar in all respects to those found in the descended testes of the sham-operated controls. Relative Leydig cell volume (% +/- SEM) was increased in the untreated cryptorchid testes compared to the surgically corrected testes (5.2 +/- 0.6 vs. 1.2 +/- 1.0; P < 0.05). Relative Leydig cell volumes in the surgically corrected testes were not significantly different from those found in the sham-operated descended controls. A modest but significant (P < 0.05) increase in absolute Leydig cell volume was also noted in the cryptorchid testes when compared both to normal controls or surgically corrected cryptorchid testes. From these observations, we conclude that early gubernaculopexy reverses the histologic changes normally seen in the cryptorchid rat testis to a relatively normal histologic architecture. These data provide experimental evidence to support the value of orchiopexy in the treatment of cryptorchidism.
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PMID:Prevention of seminiferous tubular atrophy in a naturally cryptorchid rat model by early surgical intervention. 901 4

Rodents with different hair pigmentation patterns were studied to evaluate the role of melanin in the incorporation of phencyclidine (PCP) into hair. There are two types of melanin in hair and other tissues: eumelanin, a brown-black pigment and pheomelanin, a reddish-yellow pigment. Sprague Dawley (SD; nonpigmented), Dark Agouti (DA; brown), Copenhagen (CP; brown hooded), Long Evans (LE; black hooded), and LBNF1 (deep brown) rats and Swiss-Webster (SW; nonpigmented), C57BL6 (black), and C57BL6 Ay/a (yellow) mice were administered PCP at 10 mg/kg/day for 5 days (n = 5 for each strain). Hair was collected either 14 (rats) or 35 (mice) days (mice) after beginning drug administration and analyzed for PCP, eumelanin, and pheomelanin. PCP concentrations in ng/mg (mean +/- SEM) were as follows: SD, 0.46 +/- 0.13; DA, 12.25 +/- 1.24; CP nonpigmented, 0.12 +/- 0.004; CP pigmented, 9.16 +/- 2.8; LE nonpigmented, 0.66 +/- 0.07; LE pigmented, 21.2 +/- 1.4; LBNF1, 21.64 +/- 3.8; SW, 0.48 +/- 0.36; C57 black, 11.0 +/- 4.03; and C57 yellow, 2.26 +/- 0.55. Eumelanin concentrations in microg/mg (mean +/- SEM) were as follows: DA, 20.50 +/- 1.58; CP pigmented, 19.43 +/- 0.40; LE pigmented, 17.56 +/- 0.61; LBNF1, 27.26 +/- 2.52; C57 black, 37.33 +/- 3.61; and C57 yellow, 1.76 +/- 0.02. Eumelanin was not detected in nonpigmented hair. Pheomelanin concentrations in microg/mg (mean +/- SEM) were as follows: DA, 0.09 +/- 0.00; CP pigmented, 0.20 +/- 0.03; LBNF1, 0.06 +/- 0.01; C57 black, 0.16 +/- 0.05; and C57 yellow, 29.16 +/- 0.97. Pheomelanin was not detected in nonpigmented or LE pigmented hair. These data demonstrate that PCP is incorporated into black hair to a greater extent than yellow or nonpigmented hair. There appears to be a linear relationship between the PCP concentration in hair and the ratio of eumelanin to pheomelanin. Our data suggest that despite variations in PCP concentration because of hair color, they may be normalized by using the ratio of eumelanin to pheomelanin rather than hair weight.
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PMID:The incorporation of drugs into hair: relationship of hair color and melanin concentration to phencyclidine incorporation. 978 13

This study examined plasma volume changes (deltaPV) in humans during periods with or without changes in body hydration: exercise-induced dehydration, heat-induced dehydration and glycerol hyperhydration. Repeated measurements of plasma volume were made after two injections of Evans blue. Results were compared to deltaPV calculated from haematocrit (Hct) and blood haemoglobin concentration ([Hb]). Eight well-trained men completed four trials in randomized order: euhydration (control test C), 2.8% dehydration of body mass by passive controlled hyperthermia (D) and by treadmill exercise (60% of their maximal oxygen uptake, VO2max) (E), and hyperhydration (H) by glycerol ingestion. The Hct, [Hb], plasma protein concentrations and plasma osmolality were measured before, during and after the changes in body hydration. Different Hct and [Hb] reference values were obtained to allow for posture-induced variations between and during trials. The deltaPV values calculated after two Evans blue injections were in good agreement with deltaPV calculated from Hct and [Hb]. Compared to the control test, mean plasma volume declined markedly during heat-induced dehydration [-11.4 (SEM 1.7)%] and slightly during exercise-induced dehydration [-4.2 (SEM 0.9)%] (P < 0.001 compared to D), although hyperosmolality was similar in these two trials. Conversely, glycerol hyperhydration induced an increase in plasma volume [+7.5 (SEM 1.0)%]. These results would indicate that, for a given level of dehydration, plasma volume is dramatically decreased during and after heat exposure, while it is better maintained during and after exercise.
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PMID:Plasma volume changes during and after acute variations of body hydration level in humans. 1036 16

To test the hypothesis that a chronic expansion of extracellular water (ECW), usually observed during prolonged endurance exercise, is associated with an increase in intracellular water space (ICW), total body water (TBW) and ECW were estimated before (within a week, day C-7) and after (on the 1st day of recovery, R + 1) a competition lasting 7 consecutive days in nine healthy sportsmen. The competition involved running, cycling and cross-country skiing over 620 km. Between days C-7 and R + 1, the following increases occurred - mean TBW by 4.2 (SEM 1.1) l (i.e. +10%, P = 0.01, bioelectrical impedance analysis, BIA, at 100 kHz) and by 4.1 (SEM 0.7) l (P = 0.01, dilution of 18O); mean ECW by 2.2 (SEM 0.5) l (i.e. +14%, P = 0.01, BIA at 5 kHz), and mean plasma volume (PV) by 0.7 (SEM 0.1) l (i.e. +22%, Evans blue dye dilution, P = 0.008). Consequently, mean ICW had been expanded by 2.1 (SEM 0.6) l (i.e. +8%, P = 0.01). The intensity of daily exercise evaluated from recordings of heart rate varied between 49.0% to 57.8% of maximal oxygen consumption VO2max. Water retention was highly correlated with relative exercise intensity VO2max (ICW, r = 0.86; ECW, r = 0.93; TBW, r = 0.94). Total mean plasma content of sodium increased by 104 (SEM 17) mmol (P = 0.008) while albumin and total protein contents were unchanged. We concluded that prolonged and repeated exercise induced a chronic hyperhydration at both extracellular and intracellular levels, which was related to exercise intensity. Sodium retention was the major factor in the increase of PV.
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PMID:Intracellular hyperhydration induced by a 7-day endurance race. 1048 6

Developmental exposure to polychlorinated biphenyls (PCBs) has been associated with cognitive deficits in children. The current study assessed effects of gestational and lactational exposure to a commercial PCB mixture, Aroclor 1254 (A1254), on spatial learning and memory in rats, using the radial-arm maze (RAM). Pregnant Long-Evans females (10/dose group) were exposed to 0 or 6-mg/kg/day A1254 (po in corn oil) from gestation day (GD) 6 to weaning at postnatal day (PND) 21. After they reached adulthood, 1 male and 1 female from each litter were tested on a working/reference memory task using a 12-arm RAM. Eight of the 12 arms were baited, with the pattern of baited arms remaining the same on every trial for each rat. Compared to control males, the A1254-exposed males made significantly more working memory errors (2.15 +/- 0.13 and 3.20 +/- 0.18 errors +/- SEM for control and A1254 males, respectively) and reference memory errors (3.17 +/- 0.10 and 4.13+/-0.14 errors +/- SEM for control and A1254 males, respectively) on the RAM. In contrast, A1254-exposed females were not impaired relative to control females on the RAM. Drug challenges with dizocilpine (MK-801) and scopolamine did not differentially affect working or reference memory of control and exposed rats. These data suggest that perinatal exposure to A1254 may cause sex-specific deficits in spatial learning and memory, and that NMDA-mediated and muscarinic neurotransmission, as assessed with the drug challenges, were not markedly impaired in the A1254-exposed animals.
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PMID:Gestational-lactational exposure to Aroclor 1254 impairs radial-arm maze performance in male rats. 1096 18

The coupling of periarticular lymph flow to transsynovial flow from a joint cavity, i.e., fluid load, is essential to avoid periarticular edema, which is associated with arthritic morning stiffness. To study coupling in swollen joints, a new method, "inside-out" cannulation, which eliminates dead space, resistance and cutout, was used to collect lymph from fine femoral lymph trunks in anesthetised rabbits while the knee joint cavity was infused with Evans blue albumin (EVA) at controlled intraarticular pressure and transsynovial drainage rates. The amount of joint lymph in femoral lymph (volume fraction V(v)) was calculated by EVA analysis. Joint lymph flow and EVA clearance was 1.5 +/- 0.4 microl min(-1) (mean +/- SEM, n = 62) at mean trans-synovial flow, 23 microl min(-1), and increased with pressure. Volume fraction increased from 16% at 10 cmH(2)O to 43% at 41 cmH(2)O. The increase in lymph flow with pressure, 0.052 +/- 0.025 microl min(-1) cmH(2)O(-1) (n = 61) was much smaller than the increase in transsynovial flow (periarticular fluid load) with pressure, 0.71 +/- 0.14 microl min(-1) cmH(2)O(-1) (P < 0.001). Their ratio, the coupling coefficient, was only 0.06-0.11. Thus, although up to 43% of femoral lymph could stem from a single swollen joint, this drained away only a small fraction of the transsynovial filtrate. The study showed that joint lymphatic drainage is coupled to joint pressure and transsynovial flow; but the coupling is insufficient to prevent periarticular fluid accumulation under conditions of joint volume expansion and limb immobility. This may contribute to the periarticular edema of arthritis.
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PMID:Inside-out cannulation of fine lymphatic trunks used to quantify coupling between transsynovial flow and lymphatic drainage from rabbit knees. 1207 25

Risk assessments often must consider exposures that vary over time or for which the exposure duration of concern differs from the available data, and a variety of extrapolation procedures have been devised accordingly. The present experiments explore the relationship(s) between exposure concentration (C) and time (t) to investigate procedures for assessing the risks of short-term solvent exposures. The first hypothesis tested was that the product of C x t would produce a constant health effect (Haber's rule). The second hypothesis tested was that exposure conditions produce effects in proportion to the tissue concentrations created. Awake, adult, male Long-Evans (LE) rats were exposed to trichloroethylene (TCE) vapor in a head-only exposure chamber while pattern onset/offset visual evoked potentials (VEPs) were recorded. Exposure conditions were designed to provide C x t products of 0 ppm/h (0 ppm for 4 h) or 4000 ppm/h created through four exposure scenarios: 1000 ppm for 4 h; 2000 ppm for 2 h; 3000 ppm for 1.3 h; or 4000 ppm for 1h (n = 9-10/concentration). The amplitude of the VEP frequency double component (F2) was decreased significantly by exposure; this decrease was related to C but not to t or to the C x t product, indicating that Haber's rule did not hold. The mean amplitude (+/- SEM in muV) of the F2 component in the control and treatment groups measured 4.4 +/- 0.5 (0 ppm/4 h), 3.1 +/- 0.5 (1000 ppm/4 h), 3.1 +/- 0.4 (2000 ppm/2 h), 2.3 +/- 0.3 (3000 ppm/1.3 h), and 1.9 +/- 0.4 (4000 ppm/1 h). A physiologically based pharmacokinetic (PBPK) model was used to estimate the concentrations of TCE in the brain achieved during each exposure condition. The F2 amplitude of the VEP decreased monotonically as a function of the estimated peak brain concentration but was not related to the area under the curve (AUC) of the brain TCE concentration. In comparison to estimates from the PBPK model, extrapolations based on Haber's rule yielded approximately a 6-fold error in estimated exposure duration when extrapolating across only a 4-fold change in exposure concentration. These results indicate that the use of a linear form of Haber's rule will not predict accurately the risks of acute exposure to TCE, nor will an estimate of AUC of brain TCE. However, an estimate of the brain TCE concentration at the time of VEP testing predicted the effects of TCE across exposure concentrations and durations.
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PMID:Dose-based duration adjustments for the effects of inhaled trichloroethylene on rat visual function. 1291 17

Shock-induced enhanced capillary permeability is associated with alterations in the interstitial matrix composition and contributes to organ damage. This study was designed to evaluate albumin extravasation in various organ tissues during severe, hemorrhagic shock without fluid resuscitation and reperfusion. Target value of hemorrhagic shock was a reduction of cardiac output (CO) by 50% induced by removal of blood. Twelve anesthetized Sprague-Dawley rats (260-325 g) kept under continuous hemodynamic monitoring were randomly assigned to a group of hemorrhagic shock (n = 6) and a control group of normovolemic animals (n = 6). After 30 min of shock 50 mg/kg b.w. Evans blue (EB) was injected intravenously followed by an incubation period of 20 min. Exsanguination and wash out of the intravascular space was performed by a pressure-controlled perfusion with heparinized saline before harvesting organs to quantify albumin-bound EB extravasation. We found that withdrawal of 4.7 +/- 0.4 mL (mean, +/-SEM) blood, which accounts for 21.1% of the calculated total blood volume, resulted in a reduction of CO from 36.1 +/- 3.1 to 19.4 +/- 2.7 mL/min. Simultaneously, MAP decreased from 98 +/- 6 to 40 +/- 1 mmHg. In hemorrhaged rats, the interstitial concentration of EB in lung and kidney was significantly higher than observed in intact animals, whereas heart, spleen, liver, ileum, skeletal muscle, and skin showed no significant microvascular damage. We conclude that despite the absence of fluid resuscitation and reperfusion, microvascular damage in lung and kidney is evident within the first thirty minutes of hemorrhagic shock.
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PMID:Organ-specific extravasation of albumin-bound Evans blue during nonresuscitated hemorrhagic shock in rats. 1462 82

Statins exert beneficial effects in brain diseases including stroke. Here, we investigated whether oral prophylactic atorvastatin provides long-term neuroprotection and functional recovery in permanent middle cerebral artery occlusion (pMCAO), and whether cerebral hemodynamics are affected. Male Long-Evans rats were treated with 10 mg/kg oral atorvastatin for 14 days and subjected to pMCAO. Cerebral hemodynamics were measured by bolus tracking MRI and laser Doppler flowmetry (LDF). Infarct volume was quantified at 1 week by T2-MRI and at 3 weeks by histology. Rats were also subjected to neuroscoring and cylinder test. The number of animals per group was 10. The infarct volumes were 100.8 +/- 8.2 and 47.3 +/- 5.5 mm(3) in vehicle, and 68.7 +/- 11.0 and 28.6 +/- 3.82 mm(3) in atorvastatin group at 7 and 21 days post-ischemia, respectively (mean +/- SEM). Atorvastatin significantly reduced infarct volume both at 7 and 21 days (P = 0.04 and 0.03, respectively, 1-way ANOVA). Interestingly, no improvement in cerebral hemodynamic parameters was observed in atorvastatin treated animals. The vehicle group recovered normal neuroscore at day 13, whereas atorvastatin group recovered already at day 10 after pMCAO. All treatment groups preferred to use the unaffected forelimb for rearing in Cylinder test, whereas the defected forelimb use was minimal in all groups. These results suggest that oral atorvastatin protects cerebral tissue against the subsequent pMCAO without influencing cerebral hemodynamic parameters, and it may well be that persons with ongoing atorvastatin treatment benefit in the incidence of stroke.
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PMID:Long-term protective effect of atorvastatin in permanent focal cerebral ischemia. 1602 89

Brain abscess is associated with local vasogenic edema, which leads to increased intracranial pressure and significant morbidity. Aquaporin-4 (AQP4) is a water channel expressed in astroglia at the blood-brain and brain-CSF barriers. To investigate the role of AQP4 in brain abscess-associated edema, live Staphylococcus aureus (10(5) colony-forming units) was injected into the striatum to create a focal abscess. Wild-type and AQP4-deficient mice had comparable immune responses as measured by brain abscess volume (approximately 3.7 mm3 at 3 days), bacterial count and cytokine levels in brain homogenates. Blood-brain barrier permeability was increased comparably in both groups as assessed by extravasation of Evans blue dye. However, at 3 days the AQP4 null mice had significantly higher intracranial pressure (mean +/- SEM 27 +/- 2 vs. 17 +/- 2 mmHg; p < 0.001) and brain water content (81.0 +/- 0.3 vs. 79.3 +/- 0.5 % water by weight in the abscess-containing hemisphere; p < 0.01) than wild-type mice. Reactive astrogliosis was found throughout the abscess-containing hemisphere; however, only a subset of astrocytes in the peri-abscess region of wild-type mice had increased AQP4 immunoreactivity. Our findings demonstrate a protective effect of AQP4 on brain swelling in bacterial abscess, suggesting that AQP4 induction may reduce vasogenic edema associated with cerebral infection.
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PMID:Aquaporin-4 gene deletion in mice increases focal edema associated with staphylococcal brain abscess. 1618 29


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