Comparison of two timed artificial insemination (TAI) protocols for management of first insemination postpartum.

Two estrus-synchronization programs were compared and factors influencing their success over a year were evaluated. All cows received a setup injection of PGF2alpha at 39 +/- 3 d postpartum. Fourteen days later they received GnRH, followed in 7 d by a second injection of PGF2alpha. Cows (n = 523) assigned to treatment 1 (modified targeted breeding) were inseminated based on visual signs of estrus at 24, 48, or 72 h after the second PGF2alpha injection. Any cow not observed in estrus was inseminated at 72 h. Cows (n = 440) assigned to treatment 2 received a second GnRH injection 48 h after the second PGF2alpha, and all were inseminated 24 h later. Treatment, season of calving, multiple birth, estrual status at insemination, number of occurrences of estrus before second PGF2alpha, prophylactic use of PGF2alpha, retained fetal membranes, and occurrence of estrus following the setup PGF2alpha influenced success. Conception rate was 31.2% (treatment 1) and 29.1% (treatment 2). A significant interaction occurred between protocol and estrual status at insemination. Cows in estrus at insemination had a 45.8% (treatment 1) or 35.4% (treatment 2) conception rate. The conception rate for cows not expressing estrus at insemination was 19.2% (treatment 1) and 27.7% (treatment 2). Provided good estrous detection exists, modified targeted breeding can be as successful as other timed artificial insemination programs. Nutritional, environmental, and management strategies to reduce postpartum disorders and to minimize the duration of postpartum anestrus are critical if synchronization schemes are used to program first insemination after the voluntary waiting period.

Use of estradiol cypionate in a presynchronized timed artificial insemination program for lactating dairy cattle.

Experiment 1 evaluated pregnancy rates when estradiol cypionate (ECP) was used to induce ovulation as part of a timed artificial insemination (TAI) protocol in comparison to Ovsynch for lactating dairy cows in Florida (n = 371) and Texas (n = 321). Cows were presynchronized with two injections of PGF2, (25 mg, im) given 14 d apart with TAI protocols beginning 14 d after the second injection of PGF20. The TAI protocols consisted of an injection of GnRH (100 microg, im) followed by PGF2alpha 7 d later. Then, cows either received an injection of GnRH (Treatment I, Ovsynch) at 48 h after PGF2alpha and inseminated 16 to 24 h later or received an injection of ECP (1 mg, i.m.) at 24 h after PGF2alpha, (Treatment II; Heatsynch) and inseminated 48 h later. In Florida, pregnancy rates after TAI were 37.1 +/- 5.8% for Ovsynch compared with 35.1 +/- 5.0% for Heatsynch. In Texas, pregnancy rates were 28.2 +/- 3.6% for Ovsynch and 29.0 +/- 3.5% for Heatsynch. Overall pregnancy rates did not differ between Ovsynch and Heatsynch treatments. In Experiment 2, estrus and ovulation times were determined in lactating dairy cows submitted to the Heatsynch protocol. Frequencies of detected estrus and ovulation after ECP were 75.7% (28/37) and 86.5% (32/37), respectively. Mean intervals to ovulation were 55.4 +/- 2.7 h (n = 32) after ECP and 27.5 +/- 1.1 h (n = 27) after onset of estrus. Estrus occurred at 29.0 +/- 1.8 h (n = 28) after ECP. It is recommended that any cow detected in estrus by 24 h after ECP injection be inseminated at 24 h and all remaining cows be inseminated at 48 h because 75% (n = 24/32) of the ovulations occurred between > or = 48 h to < or = 72 h after ECP. Synchronization of ovulation and subsequent fertility indicated that estradiol cypionate could be used to induce ovulation for successful timed insemination.

Influence of contact time and concentration of chlorhexidine varnish on mutans streptococci in interproximal dental plaque.

This study describes the effects of varnishes containing 0, 25, 33 and 40% chlorhexidine diacetate on mutans streptococci in human approximal dental plaque. The chlorhexidine release from the varnishes was determined in vitro. Eleven subjects participated in the clinical experiment, each with at least five approximal areas harboring high levels of mutans streptococci. The approximal areas in each of the individuals were randomly assigned to five experimental groups, in each of which one of the varnishes was tested; 40% chlorhexidine varnish was tested in two experimental groups. The varnish treatment consisted of a single application of a small amount of varnish onto the selected approximal areas. From one of the sites receiving the 40% chlorhexidine varnish, all visible varnish was removed 15 min after application. The volunteers were asked to leave the varnish on the remaining treated sites and not to brush their teeth for 8 h. All chlorhexidine varnishes strongly suppressed mutans streptococci until 4 months after the varnish application. The extent of the suppression depended upon the concentration of chlorhexidine in the varnish, 40% chlorhexidine varnish giving the greatest suppression of mutans streptococci. No significant difference was found between the numbers of mutans streptococci from sites where the 40% varnish was removed after 15 min and sites where the 40% chlorhexidine varnish was left. The results suggested that 40% chlorhexidine varnish can be used successfully for the long-term suppression of mutans streptococci. A contact time of the varnish with the tooth surface of only 15 min is sufficient to achieve this long-term suppression.

Endogenously formed norharman (beta-carboline) in platelet rich plasma obtained from porphyric rats.

Porphyria was induced in adult male Wistar rats starved for 24 hr by SC injection of 400 mg/kg allylisopropylacetamide (AIA). The presence of porphyria was shown by measuring excretion of delta-aminolevulinic acid (delta-ALA) and porphobilinogen (PBG) into the urine during 24 hr after AIA administration. Plasma levels of glycine, serine and of a number of other amino acids were decreased in porphyric rats as compared to controls. Intraperitoneal injection of 2 mmol/kg serine 24 hr after AIA administration was used as an animal model for an acute psychosis, by measuring catalepsy scores 30 min after serine injection. The concentration of 5 different beta-carbolines in platelet rich plasma (PRP) was measured using an HPLC-fluorometric method. An increase in the concentration of norharman (NH) in PRP, ranging from 0.57 nmoles/l in control rats to 1.88 nmoles/l in serine treated porphyric rats was found. The catalepsy duration was exponentially correlated with the NH concentrations in PRP. It is concluded that an elevated conversion of serine into glycine via serine hydroxymethyltransferase (SHMT) may be responsible for the enhanced NH biosynthesis.

Succinic semialdehyde as a substrate for the formation of gamma-aminobutyric acid.

The conversion of succinic semialdehyde into gamma-aminobutyric acid (GABA) by GABA-transaminase was measured in rat brain homogenate in the presence of different concentrations of the cosubstrate glutamate. The calculated kinetic parameters of succinic semialdehyde for GABA-transaminase were a limiting Km value of 168 microM and a limiting Vmax value of 38 mumol g-1 h-1. Combination with previously obtained data for the conversion of GABA into succinic semialdehyde revealed a kEq value of 0.04, indicating that equilibrium of GABA-transaminase is biased toward the formation of GABA. The increased formation of GABA in the presence of succinic semialdehyde was not due to an increased conversion of glutamate into GABA by glutamic acid decarboxylase. Therefore these results indicate that succinic semialdehyde can act as a precursor for GABA synthesis.

High-performance liquid chromatography of tetrahydro-beta-carbolines extracted from plasma and platelets.

A fast method for extraction and concentration of tryptamine (TA), 5-hydroxy-TA, and 5-methoxy-TA was developed using reverse-phase C-18 sample preparation columns in combination with an ion-pairing reagent. Using this method, 1,2,3,4-tetrahydro-beta-carboline (THBC), 6-hydroxy-THBC, and 6-methoxy-THBC, the respective reaction products formed after reaction of formaldehyde with the primary amines mentioned above, and beta-carboline (BC, norharman) and 1-methyl-beta-carboline (1-Me-BC, harman) could also be extracted from human and rat platelets and platelet-poor plasma (PPP). A HPLC method combined with fluorometric detection was developed for the quantitative determination of these compounds in the picomole range. The formation of beta-carbolines during the extraction procedure was below the limit of detection of the assay procedure. 6-OH-THBC, THBC, 1-Me-BC, and 5-HT were identified as normal constituents of human platelets, whereas only 5-hydroxytryptamine (5-HT) and 6-OH-THBC could be identified in human PPP. In rat platelets and PPP 5-HT, but no THBCs, could be detected.

Serine and glycine-induced catalepsy in porphyric rats: an animal model for psychosis?

It was investigated whether an increased demand for glycine, as postulated to occur in patients who have suffered from episodic psychoses accompanied by multiple perceptual distortions, could evoke psychotic reactions. Catalepsy was used as a measure for psychosis and was observed after injection of serine or glycine in porphyric rats. Catalepsy was was shown to occur after serine as well as glycine administration in 2-allyl-2-isopropylacetamide (AIA) pretreated rats, while in lead (Pb) + phenobarbital pretreated rats only glycine was effective. Administration of AIA to rats resulted in a strongly enhanced excretion of porphobilinogen (PBG) in urine, while Pb + phenobarbital pretreated rats showed increased excretion of delta-aminolevulinic acid (delta-ALA). The Pb + phenobarbital pretreated animals showed elevated serine plasma levels and lowered glycine plasma levels 18 hours after injection, while no significant differences in plasma levels of these amino acids were found 24 hours after AIA administration. In AIA or saline pretreated animals, but not in those pretreated with Pb + phenobarbital, glycine formation from serine was elevated. It is concluded that the present animal model can be used to investigate episodic psychoses.