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Biomedical subjects

M E Gross

Publications and source records attributed to M E Gross.

At least 19 recordsLinked to original sources
PubMed2000

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized cats.

OBJECTIVE: To determine whether anesthesia of the infraorbital and inferior alveolar nerves abolishes reflex-evoked muscle action potentials (REMP) during tooth-pulp stimulation in halothane-anesthetized cats. ANIMALS: 8 healthy adult cats. PROCEDURE: In halothane-anesthetized cats, an anodal electrode was attached to the tooth to be stimulated and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. Cathodal and anodal electrodes were moved to the upper and lower canine, upper fourth premolar, and lower first molar teeth for stimulation; baseline REMP was recorded. A 25-gauge 1-cm needle was inserted 0.5 cm into the infraorbital canal. A 25-gauge 1-cm needle was inserted 1 cm rostral to the angular process of the ramus, and advanced 0.5 cm along the medial aspect. Chloroprocaine was injected at each site. Each tooth was stimulated every 10 minutes for 90 minutes. RESULTS: REMP was abolished within 10 minutes for all upper teeth, except for the upper canine tooth in 1 cat, and abolished within 10 minutes for lower teeth in 4 cats. In 1 cat, REMP was not abolished in the lower first molar tooth. In 3 cats, REMP was not abolished in the lower canine and first molar teeth. At 90 minutes, REMP was restored for all teeth except the lower canine tooth in 1 cat, for which REMP was restored at 120 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Regional anesthesia of the infraorbital and inferior alveolar nerves may provide dental analgesia in cats.

Anesthesia, Conduction↗
PubMed1998

Clinical evaluation comparing AxSYM CA 15-3, IMx CA 15-3 and Truquant BRTM RIA.

A retrospective clinical study was conducted to compare results obtained by AxSYM(R) CA 15-3(TM), IMx(R) CA 15-3 and Truquant(R) BRTM RIA using surplus serum specimens from healthy volunteers and patients with benign and malignant diseases. Linear regression analysis of AxSYM and IMx CA 15-3 versus Truquant BR RIA for specimens with results 0-250 U/ml gave correlation coefficients of 0. 888 and 0.910 and slopes of 0.67 and 0.69, respectively. For specimens with results 0-2,000 U/ml, slopes were 0.95 and 0.91, respectively. Receiver operator characteristic analyses, based on results from healthy females plus nonmalignant disease patients versus breast cancer patients, for all three assays gave essentially equivalent areas under the curves. Concordance between AxSYM or IMx CA 15-3 and Truquant BR RIA was greater than 92%. Serial dilution of seven serum specimens yielded linear regression correlation coefficients ranging from 0.997 to 1.000 for AxSYM and IMx CA 15-3, and from 0.962 to 0.998 for Truquant BR RIA. The average percent CVs of the calculated assay values for the 7 specimens were 4.9, 2.7 and 18.1 for AxSYM CA 15-3, IMx CA 15-3 and Truquant BR RIA, respectively. Average percent recoveries ranged from 96.2 to 110.7 for AxSYM and IMx CA 15-3, and 81.8 to 93.3 for Truquant BR RIA. Although assay values differ between the two methodologies, AxSYM CA 15-3, IMx CA 15-3 and Truquant BR RIA showed comparable trending results for the 24 breast cancer patients evaluated for serial monitoring.

Adult↗
PubMed1997

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized dogs.

OBJECTIVE: To document that regional anesthesia of the infraorbital and inferior alveolar nerves would abolish reflex-evoked muscle action potentials (REMP) in the digastricus muscle during noninvasive stimulation of tooth pulp in halothane-anesthetized dogs. DESIGN: Prospective study. ANIMALS: 9 healthy female dogs between 2 and 6 years old. PROCEDURE: Dogs were anesthetized using halothane. An alligator clip anodal electrode was attached to the tooth to be stimulated, and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. The cathodal and anodal electrodes were moved to the left upper and lower canine, fourth premolar, and first molar teeth for sequential stimulation. Baseline recording of REMP was made for each tooth. Catheters were inserted percutaneously in the infraorbital and mandibular canals. Saline (0.9% NaCl) solution was injected at each catheterized site in 3 control dogs, and chloroprocaine hydrochloride was injected at each catheterized site in 6 test dogs. Each tooth was stimulated every 10 minutes for 90 minutes (test dogs) or every 10 minutes for 30 minutes and at 90 minutes (control dogs), and REMP was recorded. RESULTS: REMP was abolished within 10 minutes in all test dogs, except during stimulation of the lower first molar in 1 dog. In 4 dogs, duration of blockade was less than 90 minutes. The REMP was not restored within 90 minutes for the upper teeth in 1 dog and within 2 hours for all teeth in another dog. At 24 hours, REMP was restored for all teeth except the lower left canine in 1 dog. The REMP was restored for the lower left canine in that dog at 96 hours. The REMP was not abolished at any time in control dogs. CLINICAL IMPLICATIONS: Regional anesthesia of the infraorbital and inferior alveolar nerves may effectively provide analgesia for dental procedures in dogs.

Action Potentials↗
PubMed1995

In vitro antimicrobial effect against Streptococcus pneumoniae of adding rifampin to penicillin, ceftriaxone, or 1-ofloxacin.

Adding rifampin to penicillin or l-ofloxacin diminished the rate at which these antibiotics killed 21 clinical isolates isolates of Streptococcus pneumoniae in vitro. A less pronounced inhibitory effect was observed when rifampin was added to ceftriaxone. Synergy was not observed for any bacterial isolate. The in vitro demonstration of indifference or antagonism using these antibiotic combinations argues against the empirical addition of rifampin to beta-lactams or fluoroquinolones in treating serious pneumococcal infections.

Anti-Bacterial Agents↗
PubMed1995

Antimicrobial activities of beta-lactam antibiotics and gentamicin against penicillin-susceptible and penicillin-resistant pneumococci.

The MICs of penicillin and cefotaxime for a range of penicillin-susceptible and penicillin-resistant isolates of Streptococcus pneumoniae were unchanged by the addition of gentamicin. In time-kill studies the rate of killing was greater for 18 of 20 isolates in the presence of gentamicin. However, mean differences in killing after 6 h of incubation were modest, not exceeding 1 log10 unit.

Anti-Bacterial Agents↗
PubMed1994

Excitement in an elephant after intravenous administration of atropine.

A 28-year-old Asian elephant (Elephas maximus) was anesthetized for cesarean section to remove a dead calf. The elephant was sedated with azaperone, and atropine was administered IV 90 minutes later in preparation for induction of anesthesia with etorphine HCl. Within 1 minute of injection of atropine, the elephant began swaying, kicking, and moving in an agitated manner around the stall. There is considerable variation among species in the toxicity of atropine, although development of toxicosis usually is associated with overdosage.

Anesthesia↗
PubMed1993

Effects of abdominal insufflation with nitrous oxide on cardiorespiratory measurements in spontaneously breathing isoflurane-anesthetized dogs.

Cardiorespiratory effects of abdominal insufflation were evaluated in 8 dogs during isoflurane anesthesia. Each dog was studied 3 times, in 1 of the following orders of insufflation pressures: 10-20-30, 20-30-10, 30-20-10, 10-30-20, 20-10-30, and 30-10-20 mm of Hg. Anesthesia was induced by use of a mask, dogs were intubated, and anesthesia was maintained by isoflurane in 100% oxygen. After instrumentation, baseline values were recorded (time 0), and the abdomen was insufflated with nitrous oxide. Data were recorded at 5, 10, 15, 20, 25, and 30 minutes after insufflation. The abdomen was then desufflated, with recording of data continuing at 35 and 40 minutes. Mean arterial pressure increased at 5 minutes during 20 mm of Hg insufflation pressure, and from 20 to 30 minutes during 30 mm of Hg pressure. Tidal volume decreased from 5 to 30 minutes during 10 and 20 mm of Hg pressures, and from 5 to 40 minutes during 30 mm of Hg pressure. Minute ventilation decreased at 10 and 20 minutes during 20 mm of Hg pressure. End-tidal CO2 concentration increased from 5 to 30 minutes during 20 and 30 mm of Hg pressure. The PaCO2 decreased at 40 minutes during 10 mm of Hg pressure, at 30 minutes during 20 mm of Hg pressure, and from 10 to 40 minutes during 30 mm of Hg pressure. Values for pH decreased from 10 to 30 minutes during 20 and 30 mm of Hg pressures. The PaO2 decreased from 20 to 40 minutes during 10 mm of Hg pressure, at 30 minutes during 20 mm of Hg pressure, and from 10 to 40 minutes during 30 mm of Hg pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1992

Yohimbine/flumazenil antagonism of hemodynamic alterations induced by a combination of midazolam, xylazine, and butorphanol in dogs.

Reversal of hemodynamic alterations induced by midazolam maleate (1.0 mg/kg of body weight), xylazine hydrochloride (0.44 mg/kg), and butorphanol tartrate (0.1 mg/kg) with yohimbine (0.1 mg/kg) and flumazenil (0.25 mg/kg) was evaluated in 5 dogs. The dogs were anesthetized with isoflurane for instrumentation. With return to consciousness, baseline values were recorded, and the midazolam/xylazine/butorphanol mixture with glycopyrrolate was administered IV. Hemodynamic data were recorded for 60 minutes, and then a reversal mixture of yohimbine and flumazenil was administered IV. All variables were measured 1 minute from beginning of the reversal injection. Mean arterial pressure, pulmonary arterial pressure, systemic vascular resistance, and right ventricular stroke work index increased significantly (P < 0.05) above baseline at 60 minutes. Cardiac index and central venous pressure significantly decreased below baseline at 60 minutes. After reversal, mean arterial pressure and central venous pressure significantly decreased from baseline, whereas cardiac index, pulmonary arterial pressure, and right ventricular stroke work index increased significantly above baseline. Heart rate, cardiac index, and right ventricular stroke work index increased significantly above the 60-minute value after reversal. Mean arterial pressure and systemic vascular resistance decreased significantly (P < 0.05) below the 60-minute value after reversal. The hemodynamic alterations accompanying midazolam/xylazine/butorphanol sedation-anesthesia may be rapidly reversed with a combination of yohimbine and flumazenil.

Anesthesia↗
PubMed1991

Cellular growth response to epidermal growth factor in colon carcinoma cells with an amplified epidermal growth factor receptor derived from a familial adenomatous polyposis patient.

The receptor binding and cellular growth responses to exogenous epidermal growth factor (EGF) were studied using the DiFi cell line established from a familial adenomatous polyposis patient. The number of cell membrane EGF receptors on DiFi cells, as measured by competitive radioligand binding assays and Scatchard analysis of 125I-EGF binding isotherms, was calculated to be 4.8 x 10(6) receptors/cell. An acid prewash step performed prior to ligand binding assays did not reveal additional receptor numbers. A single, low-affinity receptor population was identified by Scatchard analysis, with an apparent Kd of 4.6 nM. This result was confirmed by radioligand binding studies performed in the presence and absence of the receptor-antagonist monoclonal antibody 528 IgG that binds predominantly to the low-affinity form of the EGF receptor. DiFi cells at 50-60% confluence, when exposed to 50 nM exogenous EGF, exhibited a rapid but partial (30%) reduction in their cell membrane-associated receptor, characteristic of sequestration. Exposure of DiFi cells to 50 nM EGF for longer periods of time (4 h) did not result in any further reduction in EGF-receptor number. The cellular growth response of DiFi cells to exogenous EGF was studied in monolayer cultures as well as in a soft agarose assay. Inhibition of soft agar colony formation was observed at exogenous EGF concentrations greater than 1.7 nM, and inhibition of monolayer growth occurred at EGF concentrations greater than 1 nM. In immune complex kinase assays, the DiFi receptor showed similar specific activity to that from the well-characterized A431 cell line. Additionally, phosphorylation of the receptor on tyrosine was qualitatively similar to that of A431 cells, further suggesting that the DiFi receptors identified by EGF-binding studies were biologically functional.

Adenomatous Polyposis Coli↗
PubMed1990

Pharmacokinetics of atenolol enantiomers in humans and rats.

Single dose pharmacokinetics of atenolol (AT) enantiomers was studied in human volunteers and in rats. After oral administration of 50 mg of racemic AT to humans, the areas under the plasma concentration-time curves (AUCs; mean +/- SD) were 1640 +/- 602 and 1860 +/- 652 (ng/mL)h for the S(-)- and R(+)-enantiomers, respectively (p less than 0.05). The small difference in the AUC was a reflection of a slight, but statistically significant (p less than 0.05) difference in the renal clearance (CLr, mL/min) of the enantiomers [129 +/- 32, S(-)-AT; 120 +/- 29, R(+)-AT]. However, the two enantiomers were not different from each other (p greater than 0.05) with respect to the volume of distribution (V lambda, L/kg) [0.879 +/- 0.342, S(-)-AT; 0.790 +/- 0.255, R(+)-AT] or the terminal elimination rate constant (lambda z, h-1) [0.113 +/- 0.038, S(-)-AT; 0.114 +/- 0.036, R(+)-AT]. After iv administration of 10 mg/kg of the racemic AT to rats, the R(+)-enantiomer achieved higher AUC values [(ng/mL)h] compared with its antipode (p less than 0.05) [3630 +/- 1040, S(-)-AT; 4020 +/- 1080, R(+)-AT]. Similar to the human results, this difference was due to a stereoselective renal clearance (mL/min/kg) in favor of S(-)-AT [14.9 +/- 5.78, S(-)-AT; 13.0 +/- 4.88, R(+)-AT; p less than 0.05].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Introduction to endoscopy.

Endoscopy is an area of rapidly growing interest within veterinary medicine. This is understandable, because it is a relatively noninvasive procedure in which a tremendous amount of diagnostic data may be obtained. The purpose of this article is to introduce the novice to the equipment and potential uses of endoscopy.

Anesthesia↗
PubMed1988

Predator-induced trophic shift of a free-living ciliate: parasitism of mosquito larvae by their prey.

Larvae of the treehole mosquito, Aedes sierrensis, release a waterborne factor that induces morphogenesis of one of their prey, the tetrahymenid ciliate Lambornella clarki. Induced free-living trophonts of L. clarki undergo a synchronous response in which cells divide and transform into parasitic cells (theronts) that encyst on larval predators. Parasitic ciliates penetrate the cuticle, enter the hemocoel, and ultimately kill their predator-host. In nature, this trophic shift can lead to predator extinction and dramatic changes in microbial populations. Facultative parasitism by this polymorphic ciliate may have evolved as an antipredator strategy. The experimentally inducible parasitic response of L. clarki provides a novel model for studying cellular morphogenesis of ciliated protozoa.

Aedes↗
PubMedDate not supplied

Evaluation of three midazolam-xylazine mixtures. Preliminary trials in dogs.

The depressant effects of midazolam and xylazine on the central nervous system (CNS) were evaluated in 12 dogs. Xylazine was administered to six dogs (1.1 mg/kg intravenously [IV]) followed in 5 minutes by midazolam (1.0 mg/kg intramuscularly [IM]). In a second group of six dogs, xylazine (2.2 mg/kg IM) was followed in 5 minutes by midazolam (1.0 mg/kg IV). Both drug regimens induced rapid and profound sedation or anesthesia. Duration of action varied with the doses and routes of administration. Dogs given the high dose of xylazine IM had an arousal time of 95.4 +/- 8.9 minutes and a walking time of 155.4 +/- 8.8 minutes. These values exceeded the IV xylazine values threefold. Partial reversal of CNS depression was accomplished with either a benzodiazepine antagonist (flumazenil) or an alpha-2 antagonist (yohimbine). In a separate trial, a mixture of xylazine (0.55 mg/kg), midazolam (1.0 mg/kg), and butorphanol (0.1 mg/kg) with and without glycopyrrolate was evaluated in eight dogs. As with the xylazine-midazolam combinations, the CNS depressant effect of this mixture was clinically indistinguishable from anesthesia achieved with other rapid-acting injectable agents. Clinical signs of CNS depression were readily and completely antagonized by the simultaneous injection of flumazenil and yohimbine.

Anesthesia↗
PubMedDate not supplied

Hemodynamic effects of intravenous midazolam-xylazine-butorphanol in dogs.

The hemodynamic effects of a mixture of midazolam (1.0 mg/kg), xylazine (0.44 mg/kg), and butorphanol (0.1 mg/kg) were evaluated in six adult dogs. The dogs were anesthetized with isoflurane for instrumentation. As the dogs returned to consciousness, baseline values were recorded and the midazolam-xylazine-butorphanol mixture and glycopyrrolate (0.01 mg/kg) were administered intravenously (IV). Hemodynamic data were recorded 3, 10, 20, 30, 40, 50, and 60 minutes after injection. Mean arterial pressure (AP), mean pulmonary arterial pressure (PAP), heart rate (HR), rate-pressure product (RPP), mean pulmonary capillary wedge pressure (PCWP), systemic vascular resistance (SVR), and right ventricular stroke work index (RVSWI) were increased significantly above baseline values. Cardiac output (CO), stroke volume (SV), cardiac index (CI), stroke index (SI), mean central venous pressure (CVP), and left ventricular stroke work index (LVSWI) were decreased significantly below baseline values. When administered IV at the dosages used in this study, midazolam-xylazine-butorphanol-glycopyrrolate induced profound acute alterations in several critical hemodynamic variables.

Animals↗