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Biomedical subjects

A D Mayer

Publications and source records attributed to A D Mayer.

At least 91 records · Page 5Linked to original sources
PubMed1993

Persistent effects on maternal aggression of pregnancy but not of estrogen/progesterone treatment of nonpregnant ovariectomized rats revealed when initiation of maternal behavior is delayed.

Two experiments explored the effects on subsequent maternal aggression of interspersing 5-24 days between pregnancy termination and pup exposure to elicit maternal behavior. Pregnancy-terminated females displaying maternal behavior were compared to nonpregnant females also stimulated by pups to behave maternally and to pregnancy-terminated groups that were not exposed to pups. Pregnancies were terminated by hysterectomy-ovariectomy on Gestation Day 19 (G19), with pup exposure commencing after 6 days (Expt. 1), and by Cesarean section + ovariectomy (OVX), after delays of 5, 10, or 24 days (Expt. 2). In each study pregnancy-terminated, maternal groups were more aggressive than both nonpregnant, maternal groups and pregnancy-terminated, nonmaternal groups regardless of the imposed delays. In Expt. 2, postsurgical interval also was a significant factor, suggesting that surgical stress may elevate maternal aggression for several days. Prolonged treatment of nonpregnant OVX females (Expt. 3) with estrogen and progesterone elevated maternal aggression when pup exposure commenced 2 but not 7 days after termination of hormone treatment (Expt. 3). Therefore the physiological changes initiated during pregnancy that support maternal aggression persist for at least 4 weeks and may involve factors in addition to ovarian hormones that stimulate maternal behavior and maternal aggression. An additional unexpected finding was that nonpregnant (OVX) females had significantly higher Aggression scores after initiating maternal behavior.

Aggression↗
PubMed1993

Peripheral olfactory deafferentation of the primary olfactory system in rats using ZnSO4 nasal spray with special reference to maternal behavior.

A modified method of applying ZnSO4 to the olfactory mucosa is described. Treated rats experienced severe nasal congestion that cleared within 24 h; more persistent morbidity did not occur. Nonpregnant females observed with male intruders 24 h following ZnSO4 showed no alterations in behavior other than a reduction in anogenital sniffing, indicating that they were not hypoactive or irritable. In other experiments, lactating females were observed in a hole-board apparatus; 2 days posttreatment anosmia was confirmed in 80% of bilaterally ZnSO4-treated females by the absence of preference for pup odors. After bilateral but not unilateral ZnSO4 treatment, initially activity scores and nose pokes were equivalent in all groups, but later they both were lower than in controls, probably due to a more rapid habituation to the novel apparatus. We conclude that intranasal ZnSO4 by small-volume spray is a useful experimental tool.

Administration, Intranasal↗
PubMed1993

Primary biliary cirrhosis. Histological evidence of disease recurrence after liver transplantation.

Histological evidence of primary biliary cirrhosis (PBC) recurring after orthotopic liver transplantation (OLT) was looked for in a 'blinded' study of 353 biopsies from 188 patients, 12-100 months post-transplant. Biopsies (172) were obtained from 83 patients transplanted for PBC and 181 biopsies from 105 patients with other liver diseases. Sixteen biopsies from 13 PBC patients (16%) had features suggestive of recurrent disease. The main diagnostic findings were: mononuclear portal inflammatory infiltration (n = 16), portal lymphoid aggregates (n = 14), portal epithelioid granulomas (n = 14) and bile duct damage (n = 15). This combination of changes was not seen in any biopsy from the non-PBC group. Additional features supporting a diagnosis of recurrent disease were ductopenia (n = 7), bile ductular proliferation (n = 7), portal fibrosis (n = 6) and copper deposition (n = 5). Thirteen biopsies from 12 patients were classified as stage I or II histologically. The other patient developed progressive damage in three serial biopsies resulting in an early micronodular cirrhosis, 5 years post-transplant. These observations provide further evidence that PBC recurs after OLT. More studies are required to determine the natural history and clinical significance of the predominantly early histological changes documented so far.

Adolescent↗
PubMed1993

Peripeduncular nucleus lesions in the rat: I. Effects on maternal aggression, lactation, and maternal behavior during pre- and postpartum periods.

Bilateral peripeduncular (PPN) lesions made on the seventh postpartum day (L7) with either radiofrequency (RF) current or N-methyl-d,l-aspartic acid (NMDA)/phosphate buffered saline (PBS) reduced maternal aggression (MA) and partially inhibited lactation without producing significant deficits in other items of maternal behavior (MB). RF-PPN lesions did not interfere with prolactin secretion, which suggests that there was deficient oxytocinergic activity. The deficit in MA was not due to interruption of afferent suckling input to the PPN: either thelectomizing females (day L6) or producing bilateral knifecuts in the mesencephalon (placed caudal to the level of the PPN; Day L7) had no effect on MA, but both procedures impaired lactation. Deficits in MA produced by RF-PPN lesions developed gradually between Days L4 and L7; lesions made either prepartum or on Day L1 did not impair MA or MB. Deficits in lactation first appeared after RF-PPN lesions on Day L1.

Aggression↗
PubMed1993

Contributions of olfaction to maternal aggression in laboratory rats (Rattus norvegicus): effects of peripheral deafferentation of the primary olfactory system.

We examined the effects in postpartum female rats (Rattus norvegicus) of olfactory deafferentation by intranasal ZnSO4 on maternal aggression and retention of aggression 24 hr after pups are removed. When females were tested with pups, effects of deafferentation depended on postpartum interval; anosmia failed to reduce aggression on Lactation Day 3 (L3), but anosmia was associated with moderate reductions on L8-L12. We propose that postpartum aggression is stimulated initially by hormonal factors associated with late pregnancy but later is supported by exteroceptive stimulation. After removal of pups, although aggression scores were lower across treatment conditions, anosmic females had shorter latencies to attack and tended to elicit more submissive behavior from intruders. Data suggest that odor cues from conspecifics normally inhibit aggression by females, but this inhibition is reduced during lactation.

Administration, Intranasal↗
PubMed1993

Managing severe alcoholic hepatitis complicated by renal failure.

We examined the management and outcome of 15 patients admitted consecutively to a specialist Liver Unit with severe alcoholic hepatitis complicated by renal failure. Fourteen patients were managed conservatively. Of these, 11/14 underwent renal dialysis for a mean of 24 days. Three patients, including two requiring dialysis, recovered renal function. Despite intensive care, 12/14 patients died. Death was frequently associated with bacterial and fungal sepsis. One patient underwent liver transplantation with prompt post-operative recovery of renal function. He was discharged from hospital 16 days later, and remains abstinent from alcohol with normal liver function after one year. Most patients with renal failure complicating severe alcoholic hepatitis will die, despite intensive care including renal dialysis. Selected patients may be suitable for liver transplantation.

Adult↗
PubMed1993

Acute liver allograft rejection--is treatment always necessary?

A group of 195 consecutive adult patients who received a primary orthotopic liver allograft were reviewed retrospectively to analyze the incidence of rejection, the response to antirejection therapy, and the impact of acute rejection on the development of ductopenic rejection. The diagnosis of acute rejection (AR) was based on a combination of clinical and histological criteria, and 69.7% of the patients had at least one episode of acute rejection. Only 6.7% of the patients failed to respond to steroids and were treated with OKT3. Four (2.3%) patients developed acute vanishing bile duct syndrome (within 60 days) and 6 (3.5%) patients developed chronic rejection. Eight patients who spontaneously recovered from AR without additional immunosuppression are described in detail. In addition to histological damage, all developed significant hepatic dysfunction. Except for one patient who died from disseminated fungal infection, the 7 remaining patients are alive with excellent graft function 7 to 21 months posttransplant. While severe AR and recurrent AR should be treated without delay, some patients with mild-to-moderate rejection and hepatic dysfunction may resolve without additional immunosuppression.

Acute Disease↗
PubMed1993

Bedside percutaneous tracheostomy in critically ill patients.

Bedside percutaneous dilational tracheostomy was performed by critical care attending physicians or supervised pulmonary and critical care fellows on 100 patients in the ICU at Cook County Hospital, Chicago, over a 3-year period. A needle is inserted in the first or second tracheal interspace followed by a guidewire. The tract is enlarged with a series of dilators to allow placement of a standard tracheostomy tube. Average procedure duration for 46 patients was 6.7 +/- 2.9 min. The intraoperative complication rate was 8 percent: transient oxygen desaturation (4 percent), transient hypotension (3 percent), and paratracheal insertion (1 percent). The postoperative complication rate was 10 percent: bleeding (5 percent), stomal infection (3 percent), and subcutaneous emphysema (2 percent). One patient died of presumed innominate artery rupture. Fifteen of 37 patients who survived hospitalization were decannulated. Stomal closure occurred in 13 of these 15 patients within 3 days with a minimal residual scar. Comparison of percutaneous dilational tracheostomy with two other techniques of percutaneous tracheostomy reveals a similar success rate with a lower incidence of serious complications. Bedside percutaneous dilational tracheostomy can be performed in the ICU by trained physicians with a low complication rate. We believe it to be the procedure of choice for many critically ill patients who require tracheostomies.

Critical Illness↗
PubMed1993

Development of indications and results during 10 years of orthotopic liver transplantation.

Liver transplantation has rapidly emerged in recent years from an uncommon experimental procedure, limited to a few centers, to become a major international effort to support patients with advancing and decompensating liver disease. The excellent results which can be achieved with optimal timing and expert clinical management are now no longer in doubt. The greatest emphasis now must be on obtaining suitable high quality donors at the right time to give the patient the best opportunity to make a full and complete recovery.

Blood Transfusion↗
PubMed1992

Long-term immunosuppression after liver transplantation: are steroids necessary?

Steroid therapy was withdrawn in 85% of 152 orthotopic liver transplant recipients with grafts surviving for more than 3 months, and 87% of these remained steroid-free. Steroid therapy was restarted in 8% for reasons other than rejection. The most common was conversion of immunosuppression because of cyclosporine nephrotoxicity. The incidence of rejection after steroid withdrawal was low: 3.8% for chronic rejection (CR) and 4.5% for acute rejection. Only 3 grafts (1.9%) were lost because of CR. No risk factors have been identified for the development of CR after steroid withdrawal, but a protective role for azathioprine has been suggested.

Adolescent↗
PubMed1992

Laryngotracheal reconstruction in adults with the sternocleidomastoid myoperiosteal flap.

Subglottic or tracheal reconstruction may be required in cases of subglottic stenosis, invasive thyroid carcinoma, or trauma. The sternocleidomastoid myoperiosteal flap uses clavicular periosteum on a muscle pedicle to provide vascularity. Clavicular periosteum is fibrous and durable and will conform to the shape of the trachea, forming bone to provide stability to the airway. The procedure is relatively simple and involves single-stage reconstruction. Success has been achieved in reconstruction of long-standing subglottic and/or tracheal stenosis and in cases of extreme tracheal defects. On the basis of 8 years' experience with this flap, we present the results from a series of 26 patients who underwent subglottic or tracheal reconstruction with the sternocleidomastoid myoperiosteal flap. Twenty-five of the 26 patients were successfully decannulated. Complications have been expanded to include one case of osteomyelitis of the sternum with mediastinitis, and 1 patient required revision. Subsequently, modifications of technique and patient management have been adopted. The complications compare favorably in frequency and in seriousness with those of other techniques for laryngotracheal reconstruction. We describe additional experience with this procedure and longer follow-up to establish its position as a first-line reconstructive approach for widespread clinical use.

Adult↗
PubMed1991

Differential roles of hypogastric and pelvic nerves in the analgesic and motoric effects of vaginocervical stimulation in rats.

Bilateral transection of the pelvic and/or hypogastric nerves, which convey afferent activity from the reproductive tract, was performed to ascertain the role of these nerves in the analgesic and motoric effects of vaginocervical mechanostimulation (VS) in rats. Two indices of analgesia were used: tail flick latency to radiant heat (TFL) and vocalization threshold to electrical shock of the tail (Voc-T). Nerve cuts were performed at least one week prior to behavioral testing. Bilateral transection of both the pelvic and hypogastric nerves eliminated the analgesic effects of VS on the TFL and Voc-T tests. Bilateral transection of only the pelvic nerves reduced the number of rats showing maximal VS-induced elevation in TFL, without altering the effect of VS on Voc-T. By contrast, bilateral transection of only the hypogastric nerves attenuated the Voc-T-elevating effect of VS, without reducing the effect of VS on elevating TFL. The effects of VS on producing immobility, hindlimb extension and blockage of hindlimb withdrawal to foot pinch were eliminated by combined bilateral pelvic and hypogastric neurectomy. However, bilateral transection of either nerve alone did not significantly alter the efficacy of VS in producing these effects. These findings indicate that the pelvic and hypogastric nerves contribute to the immobility- and extensor-inducing, and flexor-inhibiting effects of VS, and differentially mediate the analgesia-producing effects of VS.

Analgesia↗
PubMed1990

Iatrogenic injury to the bile duct. Who, how, where?

We reviewed 81 patients with bile duct injuries that occurred at cholecystectomy and/or common bile duct exploration. Thirty-two of the strictures were recurrent. The median follow-up was 9 years. High injuries were inflicted during the performance of cholecystectomy while low injuries were related to common bile duct exploration. Mitigating circumstances appear to be as follows: (1) inadequate access, exposure, and assistance; (2) absence of operative cholangiogram; (3) patient's obesity; and (4) early dissection of Calot's triangle. Noncontributory factors include the following: (1) level of training of surgeon, and (2) type of institution where the operation was performed. Following repair, 15 patients eventually died and 8 suffered intermittent cholangitis and/or cirrhosis. Mortality and morbidity were related to the following: (1) level of stricture; (2) number of previous attempts at repair; and (3) adequacy of reconstruction. Mucosa-to-mucosa anastomosis without tension is essential for optimal results.

Adult↗
PubMed1990

Effects of prolonged estrogen-progesterone treatment and hypophysectomy on the stimulation of short-latency maternal behavior and aggression in female rats.

Two experiments were undertaken to examine the stimulation of home-cage and/or maternal aggressiveness by a hormonal treatment stimulating short-latency maternal behavior. Nonpregnant ovariectomized rats were treated with a 16-day regimen providing pregnancy levels of estrogen (E, 5-mm Silastic capsule) and progesterone (P, daily injection of 4 mg) followed by E and P withdrawal, with or without a terminal injection of estradiol benzoate (EB, 5 micrograms/kg). In Experiment 1, hormonally treated and control females were exposed continuously to pups and tested for aggression toward male intruders on the fifth day of pup exposure. Females receiving E/P/Oil and E/P/EB were highly aggressive whether or not they had yet shown maternal behavior, whereas vehicle-treated females were nonaggressive. In Experiment 2, hypophysectomized (HYPX) and Sham-HYPX females received either E/P/EB or a control treatment and were tested with male intruders (a) immediately preceding and (b) on the fifth day of continuous pup exposure. HYPX and Sham-HYPX females treated with E/P/EB were almost equally aggressive both preceding and following pup exposure (during which they initiated maternal care), whereas HYPX and Sham-HYPX vehicle-treated females were nonaggressive at both tests. In contrast, maternal behavior latencies were reduced by E/P/EB only among Sham-HYPX females. The results establish that an E/P/EB-treatment which elicits short-latency maternal responses also increases aggressiveness toward intruders. Pituitary products, although involved in the mediation of maternal responsiveness, do not contribute significantly to the stimulation of female aggressiveness by ovarian hormones.

Aggression↗
PubMed1990

Cytosol and nuclear estrogen receptor binding in the preoptic area and hypothalamus of female rats during pregnancy and ovariectomized, nulliparous rats after steroid priming: correlation with maternal behavior.

In a previous study, high nuclear estrogen receptor concentrations in the preoptic area (POA) were found on Day 16 of pregnancy to prime females to respond to a subsequent low dose of estradiol benzoate (EB) after hysterectomy-ovariectomy by exhibiting maternal behavior in 48 hr. Receptor concentrations in the POA were found to be higher than those in the hypothalamus (HYP). The present study investigated when nuclear estrogen receptors increase during pregnancy in POA and when the difference in receptor concentrations between POA and HYP occurs. An attempt was made to reproduce these pregnancy changes with a 16-day treatment of estrogen and progesterone in ovariectomized (OVX), nulliparous rats. In Experiment 1, we measured cytosol and nuclear estrogen receptor concentrations in the POA and HYP of female rats during pregnancy. Nuclear receptor concentrations in the POA increased beginning on Day 10, increased again on Day 16, and continued at this high level for the remainder of pregnancy. Nuclear estrogen receptor concentrations in the HYP remained at a lower level throughout most of pregnancy until Day 22 when they increased significantly. In Experiment 2, we tested the maternal behavior and measured estrogen receptor concentrations in OVX, steroid-primed, nulliparous rats after hysterectomy (H) and EB treatment. While 90% of estradiol (E) + progesterone (P)-primed females displayed short-latency maternal behavior 48 hr after H and EB treatment, 46% of E + vehicle (V)-treated controls were maternal. At 0 hr (prior to H and EB treatment), there was a significantly larger nuclear receptor accumulation in the POA but significantly attenuated receptor binding in the HYP. P treatment significantly affected cytosol and nuclear estrogen receptor dynamics. Differences in nuclear estrogen receptor concentrations were shown to be based on the number of available binding sites and not to changes in receptor affinity for estradiol.

Animals↗