Evaluation of soluble corn fiber on chemical composition and nitrogen-corrected true metabolizable energy and its effects on in vitro fermentation and in vivo responses in dogs.

Dietary fermentable fiber is known to benefit intestinal health of companion animals. Soluble corn fiber (SCF) was evaluated for its chemical composition, nitrogen-corrected true ME (TMEn) content, in vitro digestion and fermentation characteristics, and in vivo effects on nutrient digestibility, fecal fermentation end products, and modulation of the fecal microbiome of dogs. Soluble corn fiber contained 78% total dietary fiber, all present as soluble dietary fiber; 56% was low molecular weight soluble fiber (did not precipitate in 95% ethanol). The SCF also contained 26% starch and 8% resistant starch and had a TMEn value of 2.6 kcal/g. Soluble corn fiber was first subjected to in vitro hydrolytic-enzymatic digestion to determine extent of digestibility and then fermented using dog fecal inoculum, with fermentative outcomes measured at 0, 3, 6, 9, and 12 h. Hydrolytic-enzymatic digestion of SCF was only 7%. In vitro fermentation showed increased (P < 0.05) concentrations of short-chain fatty acids through 12 h, with acetate, propionate, and butyrate reaching peak concentrations of 1,803, 926, and 112 µmol/g DM, respectively. Fermentability of SCF was higher (P < 0.05) than for cellulose but lower (P < 0.05) than for pectin. In the in vivo experiment, 10 female dogs (6.4 ± 0.2 yr and 22 ± 2.1 kg) received 5 diets with graded concentrations of SCF (0, 0.5, 0.75, 1.0, or 1.25% [as-is basis]) replacing cellulose in a replicated 5 × 5 Latin square design. Dogs were first acclimated to the experimental diets for 10 d followed by 4 d of total fecal collection. Fresh fecal samples were collected to measure fecal pH and fermentation end products and permit a microbiome analysis. For microbiome analysis, extraction of DNA was followed by amplification of the V4 to V6 variable region of the 16S rRNA gene using barcoded primers. Sequences were classified into taxonomic levels using a nucleotide basic local alignment search tool (BLASTn) against a curated GreenGenes database. Few changes in nutrient digestibility or fecal fermentation end products or stool consistency were observed, and no appreciable modulation of the fecal microbiome occurred. In conclusion, SCF was fermentable in vitro, but higher dietary concentrations may be necessary to elicit potential in vivo responses.

Potato fiber as a dietary fiber source in dog foods.

Potato fiber (PF), a coproduct of potato starch manufacture, was evaluated as a potential novel fiber source in dog food. Potato fiber contained 55% total dietary fiber, 29% starch, 4% crude protein, and 2% acid-hydrolyzed fat. The PF substrate was evaluated for chemical composition, in vitro digestion and fermentation characteristics, and in vivo responses. For the in vitro hydrolytic-enzymatic digestion and fermentation experiment, raw and cooked PF substrates were first subjected to hydrolytic-enzymatic digestion to determine OM disappearance and then fermented using dog fecal inoculum. Fermentation characteristics were then measured at 0, 3, 6, 9, and 12 h. For the in vivo experiment, 10 female mixed-breed dogs (6.13±0.17 yr; 22±2.1 kg) were provided 5 diets with graded concentrations (0%, 1.5%, 3%, 4.5%, or 6%) of PF in a replicated 5×5 Latin square design. Dogs were acclimated to the test diet for 10 d, followed by 4 d of total fecal collection. Fresh fecal samples were collected to measure fecal pH and fermentation end products. In vitro digestion revealed that raw and cooked PF were 32.3% and 27.9% digested enzymatically, whereas in vitro fermentation showed that PF was fermentable through 9 h. Raw PF had greater (P<0.05) acetate, propionate, and total short-chain fatty acid (SCFA) concentrations at the 12-h time point compared with cooked PF. The in vivo experiment showed no differences in apparent total tract DM, OM, CP, acid-hydrolyzed fat, or energy digestibility of diets containing graded concentrations of PF. However, total dietary fiber digestibility exhibited a linear increase (P<0.01) with increasing PF concentrations in the diet. Overall, linear increases (P<0.01) were observed for all individual and total SCFA, with a concomitant linear decrease (P<0.01) in fecal pH with increasing dietary PF. Fecal protein catabolite concentrations were low or undetectable, with the exception of spermidine, which exhibited a linear increase with increasing concentrations of PF. These findings indicated that inclusion of PF elicited favorable fermentation characteristics without negatively affecting nutrient digestibility or stool characteristics, indicating that PF could be a functional dietary fiber source in dog foods.

Duchenne muscular dystrophy: focus on pharmaceutical and nutritional interventions.

Duchenne muscular dystrophy is a lethal X-linked muscle disease resulting from a defect in the muscle membrane protein dystrophin. The absence of dystrophin leads to muscle membrane fragility, muscle death (necrosis) and eventual replacement of skeletal muscle by fat and fibrous connective tissue. Extensive muscle wasting and respiratory failure results in premature death often by the early 20s. This short review evaluates drug and nutritional interventions designed to reduce the severity of muscular dystrophy, while awaiting the outcome of research into therapies to correct the fundamental gene defect. Combinations of dietary supplementation with amino-acids such as creatine, specific anti-inflammatory drugs and perhaps drugs that target ion channels might have immediate realistic clinical benefits although rigorous research is required to determine optimal combinations of such interventions.

Patrón pronóstico de invasión serosa (S2) en carcinoma gástrico / Prognostic pattern of serous invasion (S2) in gastric carcinoma

El pronóstico del cáncer gástrico depende de la invasión de la pared, compromiso de barreras ganglionares y de factores biológicos tumorales. El objetivo es comunicar nuestra experiencia es un patrón pronóstico asociado a subtipos de compromisos seroso gástrico. Cuarenta y cinco pacientes operados entre 1979 y 1998 cumplen las condiciones de ingreso: carcinoma avanzado, compromiso definitivo de la serosa (S2), gastrectomía total curativa, sin tratamiento complementario. Se establecen dos grupos: Grupo 1 (n:23), con invasión limitada a la membrana serosa. Grupo 2 (n:22), con invasión serosa, rotura y explosión hacia la cavidad peritoneal, pero sin invasión a órganos vecinos. Se analiza características generales y sobrevida según Kaplan-Meier, estimando diferencias con test de Wilcoxon. Las características generales de los grupos 1 y 2 son, respectivamente: Edad promedio: 61-59 años; Sexo (M/F): 16/7-13/9; ubicación tumoral (Zona A/M/C): 3/6/14 - 0/8/14; Clasificación de Bormann (I/II/III/IV): 0/4/810/1 - 0/0/9/9/4. El compromiso de barreras ganglionares (N1/N2): 15/5-13/2. Las principales complicaciones son de causa médica (22,2 por ciento, compartidas por ambos grupos uniformemente. El Grupo 2 tiene dos complicaciones quirúrgicas, tratadas en forma conservadora. Nohay mortalidad en la serie. La sobrevida a 5 años, para el grupo total (n:45) es 33,4 por ciento. La sobrevida del Grupo 1 y 2 es 47,5 por ciento, con diferencia significativa (p=0,05). En esta serie, el compromiso de serosa, abierta ala cavidad peritoneal, se comporta como un factor pronóstico negativo en la sobrevida del cáncer gástrico

Therapies for improving muscle function in neuromuscular disorders.

Muscle atrophy or wasting is a loss of muscle tissue resulting from disease or lack of use. This review examines recent pharmacologic or nutrition interventions for ameliorating wasting and improving muscle function in neuromuscular disorders. The information has application for treating the muscular dystrophies, cancer cachexia, weightlessness, immobilization, denervation, and disuse atrophy.

Testosterone and estrogen act via different pathways to inhibit puberty in the male Siberian hamster (Phodopus sungorus).

The peripubertal transition in male mammals is accompanied by a gradual decrease in sensitivity to the inhibitory effects exerted by gonadal hormones, such as T and E2. Here, we investigated the effects of chronic T and its metabolites, 5alpha-dihydrotestosterone and E2 on the hypothalamo-pituitary-gonadal axis at puberty. We also examined if T effects are distinct or mediated through its conversion to 5alpha-dihydrotestosterone or E2. Twenty-day-old male Siberian hamsters were sc implanted with a SILASTIC brand capsule containing varying doses of T, 5alpha-dihydrotestosterone, or E2. Several functional parameters of the hypothalamo-pituitary-gonadal axis were evaluated including hypothalamic GnRH concentration, pituitary and plasma FSH levels, pituitary FSH and LH mRNA, and testicular status. Our results showed that gonadal steroids inhibited puberty in a dose-dependent manner as evaluated by testes mass (undiluted steroid: T, 27 +/- 3 mg; 5alpha-dihydrotestosterone, 18 +/- 1 mg; and E2, 62 +/- 4 mg relative to cholesterol-implanted controls, 510 +/- 42 mg). Also, T decreased plasma FSH below detectable levels, but pituitary FSH concentration was unaffected (1.37 +/- 0.16 ng/microg protein) while E2-treated hamsters had normal plasma FSH levels (3.5 +/- 0.98 ng/ml) yet significantly lower pituitary FSH concentration (0.09 +/- 0.04 ng/microg protein). These results showed that the pathways of T and E2 action on the hypothalamo-pituitary-gonadal axis are distinct.

Hyperbaric oxygen modulates antioxidant enzyme activity in rat skeletal muscles.

In skeletal muscle the activity of the enzymatic antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) is regulated in response to generation of reactive oxygen species (ROS). Increased activity of these enzymes is observed after repeated bouts of aerobic exercise, a potent stimulus for intracellular ROS production. Hyperbaric oxygen (HBO) inhalation also stimulates intracellular ROS production although the effects of HBO on skeletal muscle SOD, GPx and CAT activity have not been studied. We tested the hypothesis that SOD, GPx and CAT activity is modulated in skeletal muscles in response to acute and repeated HBO administration. In adult male rats acute HBO inhalation (60 mm at 3 atmospheres absolute) reduced catalase activity by approximately 51% in slow-twitch soleus muscles. Additionally, repeated HBO inhalation (twice daily for 28 days) increased Mn2+-superoxide dismutase activity by approximately 241% in fast-twitch extensor digitorum longus muscles. We conclude that both acute and repeated HBO inhalation can alter enzymatic antioxidant activity in skeletal muscles.

Hyperbaric oxygen improves contractile function of regenerating rat skeletal muscle after myotoxic injury.

There is growing interest in hyperbaric oxygen (HBO) as an adjunctive treatment for muscle injuries. This experiment tested the hypothesis that periodic inhalation of HBO hastens the functional recovery and myofiber regeneration of skeletal muscle after myotoxic injury. Injection of the rat extensor digitorum longus (EDL) muscle with bupivacaine hydrochloride causes muscle degeneration. After injection, rats breathed air with or without periodic HBO [100% O(2) at either 2 or 3 atmospheres absolute (ATA)]. In vitro maximum isometric tetanic force of injured EDL muscles and regenerating myofiber size were unchanged between 2 ATA HBO-treated and untreated rats at 14 days postinjury but were approximately 11 and approximately 19% greater, respectively, in HBO-treated rats at 25 days postinjury. Maximum isometric tetanic force of injured muscles was approximately 27% greater, and regenerating myofibers were approximately 41% larger, in 3 ATA HBO-treated rats compared with untreated rats at 14 days postinjury. These findings demonstrate that periodic HBO inhalation increases maximum force-producing capacity and enhances myofiber growth in regenerating skeletal muscle after myotoxic injury with greater effect at 3 than at 2 ATA.

Lysosomal dysfunction results in lamina-specific meganeurite formation but not apoptosis in frontal cortex.

An inhibitor of cathepsins B and L was used to test if lysosomal dysfunction in cultured slices of rat frontal cortex induces pathological features that develop in the human cortex during aging and Alzheimer's disease (AD). Incubation for 6 days with N-CBZ-L-phenylalanyl-L-alanine-diazomethylketone (ZPAD) resulted in a massive proliferation of endosomes-lysosomes in all cortical layers. Slices additionally exposed to a washout of 4 days had numerous meganeurites, blister-like structures in the region of the axon hillock, in layer III but not in other cortical laminae. Meganeurites are a characteristic feature of the human frontal cortex after age 50 and are largely restricted to layer III. Tests for apoptosis were carried out at two intervals following meganeurite formation. TUNEL-labeled neurons were confined to layers II/III on the surface of the slices but there was no evidence for a ZPAD effect. In all, 6 days of lysosomal dysfunction reproduces characteristic effects of normal aging in neocortex without generating some key features of AD.

Experimentally induced lysosomal dysfunction disrupts processing of hypothalamic releasing factors.

Previous studies have shown that experimentally induced lysosomal dysfunction elicits various features of aging in the cortical telencephalon. The present study used cultured slices to test if: (1) it causes similar changes in the hypothalamus, and/or (2) modifies the processing of two releasing factors important to aging. A 2-day exposure to N-CBZ-L-phenylalanyl-L-alanine-diazomethylketone (ZPAD), a selective inhibitor of cathepsins B and L, triggered a pronounced increase in the numbers of lysosomes in the ventromedial and dorsomedial nuclei, and in lateral hypothalamus. Continued incubation with the inhibitor for 3-12 days resulted in the spread of endosomes-lysosomes into dendrites and, in the lateral hypothalamus, the formation of massive, lysosome-filled expansions of neuronal processes (meganeurites). These effects did not occur in the arcuate nucleus, making it the first region so far examined in which lysosomal proliferation is not initiated by hydrolase inhibitors. Despite this, a dense plexus of axons and terminals in the median eminence was partially depleted of growth hormone releasing hormone (GHRH) within 48 hours after addition of ZPAD. Moreover, the inhibitor caused axonal GHRH to become collected into large puncta, an effect highly suggestive of a partial failure in axonal transport. GHRH mRNA levels were not greatly affected by 6 days of ZPAD exposure, indicating that reduced expression did not play a major role in the peptide changes seen at 48 hours. Similar but less pronounced immunocytochemical changes were recorded for the somatostatin system in the arcuate and periventricular nucleus. It is concluded that lysosome dysfunction: (1) has different consequences for the arcuate nucleus than other brain regions, and (2) disrupts transport of hypothalamic releasing factors. The potential significance of the results to endocrine senescence is discussed.

Parámetros en el pronóstico del carcinoma gástrico avanzado: evaluación de clasificación tradicional y técnica fluocitométrica en el seguimiento de 32 casos / Parameters of the prognosis in advanced gastric carcinoma: evaluation of tradictional classification and flow cytometry technique in 32 cases

El objetivo es demostrar el valor del índice de ADN de proliferación celular (fase S) como factores de importancia pronóstica en el cáncer gástrico avanzado (CGA) frente a estudio tradicional (clasificación japonesa), comparando estadísticamente las curvas de sobrevida a 5 años (Kaplan-Meier) de 32 pacientes intervenidos entre 1979 y 1995, que cumplen con: gastrectomía total por CGA, resección curativa, sin tratamiento complementario; invasión hasta la serosa, compromiso hasta la segunda barrera ganglionar. Resultados de sobrevida: etapa I (C. Japonesa) = 63,3 por ciento, etapa II = 43,8 por ciento (p=0,3). Indice de ADN menor de 1,4=59,8 por ciento, índice de ADN mayor de 1,4=36,4 por ciento (p=0,3). Fase S menor de 35 por ciento = 71,6 por ciento, de manera similar a la clasificación tradicional, destacando la Fase S, indicando pronóstico en este grupo de pacientes con cáncer gástrico avanzado

Cáncer avanzado de la vesícula biliar: tratamiento combinado con cirugía y radioterapia: estudio prospectivo sobre 34 casos / Gallbladder advanced cancer: combined treatment by surgery and radiotherapy: prospective study about 34 cases

El cáncer vesicular en Chile es la primera causa de muertes por muertes por cáncer en mujeres, y su pésimo pronóstico a cinco años nada lo ha hecho variar. A partir de 1988, comenzamos un protocolo prospectivo de manejo del cáncer vesicular avanzado que compromete de muscular a serosa vesicular inclusive. El protocolo utilizado combina la colecistectomía con radioterapia más quimiosensibilización. Se seleccionaron para el estudio 34 pacientes con el siguiente criterio: pacientes a los que se les practicó una colecistectomia por enfermedad calculosa biliar y en quienes se encontró en la anatomía patológica del cáncer que puede comprometer desde la muscular a la serosa vesicular inclusive, y no tenían evidencias de enfermedad cancerosa extravesiculr. Veinte pacientes recibieron tratamiento complementario entre la tercera y sexta semana postcirugía consistente en: radioterapia abdomen total 2100 cG y más lecho vesicular 5400 cGy y quimiopotenciación con 5-FU 500 mg/m² y leucovorina 20 mg/m² en primera y última semana de la radioterapia. Catorce pacientes admitidos no pudieron acceder al tratamiento complementario y se transformaron, así, en nuestro grupo de control. La sobrevida global a cinco años (n=34) fue 48,7 por ciento. La sobrevida a cinco años para los pacientes con tratamiento completo (n=20) fue 62,5 por ciento. Sobrevida a cinco años para los pacientes con colecistectomia solamente (n=14) fue 28,6 por ciento. Las curvas de sobrevida entre los dos grupos establecen diferencias significativa. El estudio realizado, en que el paciente tratado en forma completa con menor seguimiento tiene 13 meses y el mayor 112 meses, con una media de 23,5 meses, y los resultados de sobrevida a cinco años de 62,5 por ciento nos permite proponer su aplicación para el manejo de pacientes portadores de cáncer vesicular así expuesto

Monitoring of cisplatin ototoxicity by distortion-product otoacoustic emissions.

Cisplatin is one of the most commonly used chemotherapeutic agents. However, ototoxicity, in particular, damage to the outer hair cells of the cochlea, is one of its major side effects. Otoacoustic emissions are acoustical signals that originate from the contractile activity of the outer hair cells. They are transmitted from the cochlea to the external ear canal via the middle ear apparatus. Testing is quick, painless, objective, and non-invasive. Distortion-product otoacoustic emissions (DPOAEs) are one of the evoked types of otoacoustic emissions. They are quite sensitive to any insult to the outer hair cells, even before damage is manifested in pure tone audiometry (PTA). A patient, who was on cisplatin chemotherapy due to prostate cancer, was monitored periodically for ototoxicity using DPOAEs and PTA. DPOAEs were found to detect ototoxicity one course of chemotherapy earlier than PTA during cisplatin chemotherapy. The clinical application and sensitivity of DPOAEs in monitoring ototoxicity were discussed.

Corticosterone exacerbates kainate-induced alterations in hippocampal tau immunoreactivity and spectrin proteolysis in vivo.

Aberrant elevations in intracellular calcium levels, promoted by the excitatory amino acid glutamate, may be a final common mediator of the neuronal damage that occurs in hypoxic-ischemic and seizure disorders. Glutamate and altered neuronal calcium homeostasis have also been proposed to play roles in more chronic neurodegenerative disorders, including Alzheimer's disease. Any extrinsic factors that may augment calcium levels during such disorders may significantly exacerbate the resulting damage. Glucocorticoids (GCs), the adrenal steroid hormones released during stress, may represent one such extrinsic factor. GCs can exacerbate hippocampal damage induced by excitotoxic seizures and hypoxia-ischemia, and we have observed recently that GCs elevate intracellular calcium levels in hippocampal neurons. We now report that the excitotoxin kainic acid (KA) can elicit antigenic changes in the microtubule-associated protein tau similar to those seen in the neurofibrillary tangles of Alzheimer's disease. KA induced a transient increase in the immunoreactivity of hippocampal CA3 neurons towards antibodies that recognize aberrant forms of tau (5E2 and Alz-50). The tau immunoreactivity appeared within 3 h of KA injection, preceded extensive neuronal damage, and subsequently disappeared as neurons degenerated. KA also caused spectrin breakdown, indicating the involvement of calcium-dependent proteases. Physiological concentrations of corticosterone (the species-typical GC of rats) enhanced the neuronal damage induced by KA and, critically, enhanced the intensity of tau immunoreactivity and spectrin breakdown. Moreover, the GC enhancement of spectrin proteolysis was prevented by energy supplementation, supporting the hypothesis that GC disruption of calcium homeostasis in the hippocampus is energetic in nature. Taken together, these findings demonstrate that neurofibrillary tangle-like alterations in tau, and spectrin breakdown, can be induced by excitatory amino acids and exacerbated by GCs in vivo.

Influence of dietary palm oil supplementation on serum lipid metabolites, carcass characteristics, and lipid composition of carcass tissues of growing ram and ewe lambs.

The objective of this research was to determine the influence of dietary palm oil supplementation on carcass characteristics and lipid composition of tissues from growing lambs. Twenty-eight Suffolk x Hampshire lambs were weaned at 60 d of age (average 36 kg BW) and assigned to a 2 x 2 factorial arrangement consisting of diet (control [NPO] or 10.6% added dietary palm oil [PO]) and sex (ram vs ewe). The NPO diet (77% forage and 23% concentrate) contained 11.2% CP and 2.66 Mcal of ME/kg. Palm oil replaced molasses in the PO diet. Lambs were individually given ad libitum access to feed for 60 d to a final BW average of 50.1 kg. Lipid composition of the longissimus muscle and corresponding subcutaneous (s.c.) adipose tissue was determined by gas-liquid chromatography (GLC). Lambs fed PO were fatter (P less than .01) than lambs fed NPO (.77 vs .56 cm, s.c. fat). Diet had no effect on cholesterol content of lean tissue; however, feeding PO increased the saturated fatty acids of lean tissue. The s.c. fat from lambs fed PO had less (P less than .01) cholesterol (64.79 vs 89.67 mg/100 g) and more saturated fatty acids than that from lambs fed NPO. Ewes were fatter (P less than .01) than rams, yet they had less cholesterol content in the s.c. adipose tissue (68.71 vs 85.74 mg/100 g). High amounts of dietary palm oil fed to growing lambs caused changes in fatty acid deposition and cholesterol metabolism and may be a useful investigative tool to study lipid metabolism in growing ruminants.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrogen metabolism of lactating ewes fed rumen-protected methionine and lysine.

Twenty multiparous, crossbred, black-faced ewes and their newborn twin lambs were assigned to one of four dietary treatments in a 2 x 2 factorial experiment to examine the effects of increased supply of CP or a mixture of encapsulated methionine and lysine or both on the performance of ewes and their nursing twin lambs. Ewes were fed ad libitum amounts of either a 10.2% low CP diet or a 16.2% moderate CP diet with or without additional encapsulated amino acids. Nitrogen metabolism trials were conducted simultaneously on both ewes and lambs at wk 2, 4, and 8 of lactation. Analyses were conducted for blood urea N, plasma 3-hydroxybutyrate, lactate, NEFA, insulin, and amino acids (plasma, feed, and milk). Ewe DMI, BW, BW gain, and milk yield were not changed by dietary treatments. Balance of N and N digested were increased by moderate CP treatment. The portion of retained N used for milk synthesis was increased by low CP treatment. Methionine and total branched-chain amino acids were increased by encapsulated amino acids and by protein treatment. Gains in BW and N balance were increased in lambs nursing ewes fed protected amino acids. Increased growth of nursing lambs would be an important beneficial effect of supplementing diets of ewes with encapsulated methionine and lysine.

Effects of urea and starch on rumen fermentation, nutrient passage to the duodenum, and performance of cows.

Four midlactation, multiparous Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design to determine the effects of supplementing urea or starch or both to diets containing fish meal on passage of nutrients to the small intestine and performance of lactating cows. The treatments (in a 2 x 2 factorial arrangement) were 1) control and control plus 2) urea, 3) starch, or 4) starch and urea. Supplementing diets with urea did not affect DMI; ruminal, postruminal, or total tract digestibilities of DM, starch, ADF, or NDF; ruminal fluid VFA concentrations or molar percentages; or ruminal fluid or particulate dilution rates. Feeding additional starch depressed DMI but did not alter ruminal or postruminal digestion of OM or VFA concentrations and molar percentages in ruminal fluid. Ruminal fluid ammonia concentration was increased by feeding urea and decreased by feeding additional starch. Passage of nonammonia N, nonammonia nonmicrobial N, or microbial N to the small intestine and efficiency of microbial CP synthesis were not affected significantly by supplying either urea or additional starch. Feeding urea increased passage of methionine to the small intestine, whereas feeding additional starch increased passage of methionine and arginine. Passage of other amino acids to the small intestine was not altered significantly by feeding urea or additional starch. Production of milk and milk protein was increased, but yields of fat and SNF were not altered by feeding diets supplemented with urea. Production of milk and milk fat was not affected, but yields of CP and SNF were decreased when additional starch was fed to cows.

Circadian differences in neuronal activity of the suprachiasmatic nucleus in brain slices prepared from photo-responsive and photo-non-responsive Djungarian hamsters.

The suprachiasmatic nucleus (SCN) of the hypothalamus, as the putative generator of circadian rhythmicity, plays an important role in mammalian photoinduction. To determine if SCN function differs in photo-non-responsive Djungarian hamsters, we defined the pattern of spontaneous neuronal discharge of single cells from SCN slices in vitro of photo-responsive and photo-non-responsive phenotypes. Responsive hamsters exhibited a peak neuronal discharge rate (4.8 +/- 0.5 Hz) during the mid day which gradually attenuated through the late day and early night. In non-responsive hamsters, a similar discharge rate (5.1 +/- 0.5) was maintained through the late day and early night. The delayed decline in spontaneous firing rate of non-responders correlates with their delayed activity onset and delayed nocturnal pineal melatonin pulse. These data support the argument that the absence of photoperiodic adjustments in Phodopus sungorus rests with differences in SCN function.

Monensin controlled-release intraruminal capsule for control of bloat in pastured dairy cows.

Monensin, a polyether ionophore antibiotic, is potentially an important agent for bloat relief in dairy cows grazing temperate legume-based pasture. A series of studies was undertaken to determine the effect of monensin, when delivered continuously in the rumen of lactating dairy cows by means of controlled-release capsules (monensin CRC). Such devices release approximately 300 mg/head/day for 100 d. A short-term pilot study made at Ruakura, New Zealand, tested monensin CRC in cows selected for high susceptibility to bloat and grazing lucerne (Medicago sativa) or red clover (Trifolium pratense). Treatment significantly reduced the incidence of bloat, while milk yield and protein yield were increased. There was no effect on fat yield. Following the pilot study, 6 large-scale field experiments involving a total of 368 lactating dairy cows, were made in Australia and New Zealand to confirm the effectiveness of monensin CRC for bloat control and to measure the effect of such treatment on milk production and composition. A severe bloat problem occurred in 2 experiments, mild bloat occurred in 2 others, while no visual signs of bloat were observed in the remaining 2 experiments. Bloat was significantly (P less than 0.05) reduced by monensin CRC treatment when data was pooled over the 4 experiments in which bloat occurred. Daily milk yield was increased in all experiments from a mean of 17.7 in untreated groups to 18.8 kg/head/day (P less than 0.05) in monensin CRC-treated cows. Protein percentage was not affected by treatment, while there was a decrease from 4.29 to 4.10% fat, although total fat yield was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)