The full Bayesian significance test for mixture models: results in gene expression clustering.

Gene clustering is a useful exploratory technique to group together genes with similar expression levels under distinct cell cycle phases or distinct conditions. It helps the biologist to identify potentially meaningful relationships between genes. In this study, we propose a clustering method based on multivariate normal mixture models, where the number of clusters is predicted via sequential hypothesis tests: at each step, the method considers a mixture model of m components (m = 2 in the first step) and tests if in fact it should be m - 1. If the hypothesis is rejected, m is increased and a new test is carried out. The method continues (increasing m) until the hypothesis is accepted. The theoretical core of the method is the full Bayesian significance test, an intuitive Bayesian approach, which needs no model complexity penalization nor positive probabilities for sharp hypotheses. Numerical experiments were based on a cDNA microarray dataset consisting of expression levels of 205 genes belonging to four functional categories, for 10 distinct strains of Saccharomyces cerevisiae. To analyze the method's sensitivity to data dimension, we performed principal components analysis on the original dataset and predicted the number of classes using 2 to 10 principal components. Compared to Mclust (model-based clustering), our method shows more consistent results.

Review article: psychological aspects of home parenteral nutrition, abnormal illness behaviour and risk of self-harm in patients with central venous catheters.

BACKGROUND: Home parenteral nutrition is established as standard management for patients with chronic severe intestinal failure. Although the treatment is welcomed by many patients, there are psychological consequences of living with a central venous catheter and there are associated restrictions to the lives of patients on home parenteral nutrition. A subgroup of home parenteral nutrition patients may use their central venous catheter for self-harm. AIMS: To review existing literature relating to abnormal psychological responses to central venous catheters in patients receiving home parenteral nutrition and the psychological meaning of living with a central venous catheter. It also attempts to alert professionals to ways in which patients may self-harm using their central venous catheters. METHODS: A literature review was performed. Data were obtained both from literature searches and from personal experience at a Psychological Medicine Unit attached to a large home parenteral nutrition centre. RESULTS: Patients receiving home parenteral nutrition may use their central venous catheter in various ways to self-harm. Motivation may be conscious or unconscious. Sequelae of such self-harm may be life-threatening. CONCLUSION: This paper concludes with recommendations for best practice with respect to the psychological management of home parenteral nutrition patients in whom central venous catheter abuse is suspected.

Intravesical nanocrystalline silver decreases experimental bladder inflammation.

PURPOSE: Interstitial cystitis is a sterile bladder inflammatory disease characterized by pelvic pain, urinary urgency and frequency. Nanocrystalline silver has anti-inflammatory properties, prompting us to investigate its effect in experimental bladder inflammation. MATERIALS AND METHODS: Nanocrystalline silver (0.01%, 0.05%, 0.1%, 0.5% or 1%) or phosphate buffered saline (Invitrogen) (0.5 ml) was introduced intravesically in Sprague-Dawley female rat (Charles River Laboratories, Wilmington, Massachusetts) bladders for 20 minutes, followed by vehicle or protamine sulfate (10 mg/ml for 30 minutes) and lipopolysaccharide (Sigma) (2 mg/ml for 45 minutes). Urine was collected throughout for histamine assay. The catheter was removed, the rat was returned to its cage and 4 hours later it was sacrificed. The bladder was harvested, minced and cultured overnight. The medium was collected for tumor necrosis factor-alpha assay. RESULTS: Mean +/- SD total urine histamine increased from 270 +/- 190 ng in 4 controls to 842 +/- 239 ng after protamine sulfate/lipopolysaccharide and it decreased to 505 +/- 187 ng in 6 animals after pretreatment with 1% nanocrystalline silver (p = 0.036). Tumor necrosis factor-alpha release in explant medium increased from 0.02 +/- 0.03 pg/mg in 6 controls to 0.28 +/- 0.15 pg/mg in 14 animals after treatment with protamine sulfate/lipopolysaccharide and it decreased to 0.12 +/- 0.11 pg/mg in 10 animals pretreated with nanocrystalline silver (p = 0.009). Nanocrystalline silver was not effective at less than 1% and at 1% alone it released 0.05 +/- 0.07 pg/mg tumor necrosis factor-alpha in 7 rats (vs phosphate buffered saline in 6, p = 0.387). Nanocrystalline silver (1%) significantly decreased bladder inflammation and mast cell activation. These effects were apparent even 4 days later. CONCLUSIONS: Intravesical administration of nanocrystalline silver (1%) decreased urine histamine, bladder tumor necrosis factor-alpha and mast cell activation without any toxic effect. This action may be useful for interstitial cystitis.

Prolonged anorexia and elevated plasma cytokine levels following myeloablative allogeneic hematopoietic cell transplant.

Myeloablative conditioning regimens commonly lead to prolonged anorexia and poor oral intake. In a prospective study of 147 patients receiving CY, total body irradiation and allogeneic hematopoietic cells, we determined the extent of decline in oral intake and assessed plasma cytokine levels and development of acute GVHD as explanations for protracted anorexia. For each patient, daily oral caloric intake was expressed as a percent of estimated basal requirements, calculated as basal energy expenditure, through day 20. Oral caloric intake was significantly reduced in 92% of patients and remained low. The nadir in oral intake occurred at days 10-12, when median oral caloric intake was 3% of basal energy requirements. Plasma cytokines known to affect appetite (IL2, IL6, tumor necrosis factor-alpha) were significantly elevated above normal following conditioning therapy (P<0.001 for each cytokine). Acute GVHD did not appear to affect oral intake to transplant day 20 in this cohort of patients; however, plasma levels of IL6 rose steeply before the clinical onset of GVHD. Persistent fever occurred with the greatest frequency in patients with most profound reduction in oral intake. We conclude that prolonged alterations in oral intake following this myeloablative regimen may be related to circulating cytokines known to alter eating behavior.

Genuine Bayesian multiallelic significance test for the Hardy-Weinberg equilibrium law.

Statistical tests that detect and measure deviation from the Hardy-Weinberg equilibrium (HWE) have been devised but are limited when testing for deviation at multiallelic DNA loci is attempted. Here we present the full Bayesian significance test (FBST) for the HWE. This test depends neither on asymptotic results nor on the number of possible alleles for the particular locus being evaluated. The FBST is based on the computation of an evidence index in favor of the HWE hypothesis. A great deal of forensic inference based on DNA evidence assumes that the HWE is valid for the genetic loci being used. We applied the FBST to genotypes obtained at several multiallelic short tandem repeat loci during routine parentage testing; the locus Penta E exemplifies those clearly in HWE while others such as D10S1214 and D19S253 do not appear to show this.

Genuine Bayesian multiallelic significance test for the Hardy-Weinberg equilibrium law

Statistical tests that detect and measure deviation from the Hardy-Weinberg equilibrium (HWE) have been devised but are limited when testing for deviation at multiallelic DNA loci is attempted. Here we present the full Bayesian significance test (FBST) for the HWE. This test depends neither on asymptotic results nor on the number of possible alleles for the particular locus being evaluated. The FBST is based on the computation of an evidence index in favor of the HWE hypothesis. A great deal of forensic inference based on DNA evidence assumes that the HWE is valid for the genetic loci being used. We applied the FBST to genotypes obtained at several multiallelic short tandem repeat loci during routine parentage testing; the locus Penta E exemplifies those clearly in HWE while others such as D10S1214 and D19S253 do not appear to show this.

Psychiatry, psychotherapy and gastroenterology -- bringing it all together.

In this review, some aspects of functional gastrointestinal disorders are described, with particular reference to psychiatric and psychological features. Seven syndromes or conditions, which may present not uncommonly in a gastroenterology clinic, are identified and clarified. Thereafter, the roles of a psychiatrist and other mental health professionals (psychotherapists, psychologists) within gastroenterology are described, with particular reference to what an integrated service may offer.

GABA(A) receptor regulation of kyphotic nursing and female sexual behavior in the caudal ventrolateral periaqueductal gray of postpartum rats.

Bilateral lesions of the ventrolateral caudal periaqueductal gray inhibit lordosis and kyphosis, the postures of female sexual receptivity and maternal nursing that are characterized respectively by dorsoflexion and ventroflexion of the spinal column. These lesions also inhibit the solicitation behaviors that accompany lordosis, but they do not impair retrieval or licking of pups. We tested the hypothesis that reproductive behaviors affected by these lesions are tonically inhibited by activity of the GABA(A) receptor via site-specific manipulations of receptor activity. Rats were bilaterally implanted during pregnancy with guide cannulae aimed at the caudal periaqueductal gray and ovariectomized on day 1 postpartum. Microinfusions (0.25 microl/side) of saline or drug took place on days 5 and 7 postpartum into the dorsolateral column and on days 9 and 11 into the ventrolateral column. Five minutes post-infusion dams were reunited with their pups and their maternal behavior was observed for 30 min. Feminine sexual behaviors were evaluated post-weaning after another set of microinfusions in the ventrolateral caudal periaqueductal gray. Potential facilitation of kyphosis and lordosis was tested with the GABA(A) antagonist bicuculline (15 ng/side) during sub-threshold conditions, i.e., non-suckling pups or sub-threshold ovarian hormone dosages; potential inhibition of these postures was tested with the GABA(A) agonist muscimol (125 ng/side) during optimal conditions, i.e., suckling pups or supra-threshold ovarian hormone treatments. Dorsolateral drug manipulations were ineffective. In the ventrolateral periaqueductal gray bicuculline significantly increased and muscimol significantly decreased kyphosis, lordosis, and sexual solicitations compared with saline. Retrieval and licking of pups were not altered by GABA(A) manipulations. These findings suggest that the reproductive postures of female rats, lordosis and kyphosis, as well as sexual solicitations, are tonically inhibited by the neurotransmitter GABA within the ventrolateral caudal periaqueductal gray in the midbrain. In contrast, retrieval and licking of pups appear to be under separate neurochemical or neuroanatomical control, or both. Further, this tonic inhibition is likely relieved by excitatory somatosensory inputs to this site, from mounting and suckling respectively.

Neural mediation of nursing and related maternal behaviors.

Nursing is the behavioral concomitant of lactation and the most generalizable maternal behavior across mammals. In lactating rats nursing often occurs in the kyphotic (upright crouched) posture; like the neuroendocrine determinants of milk synthesis and release, kyphosis requires suckling by the young. The dam's active pronurturant behaviors, such as retrieval and licking of pups, requires perioral somatosensory stimulation, which is often a precursor of kyphosis as well, and is inhibited by suckling. The sequential nature of maternal behaviors and the dissociations in their somatosensory regulation are critical to understanding their neural mediation, as exemplified by our recent work in lactating rats. We found that the caudal lateral and ventrolateral midbrain periaqueductal gray (cPAGl,vl) is a sensorimotor integration site for the kyphotic nursing posture. Destruction of the cPAGl,vl, or increased activity of the inhibitory neurotransmitter GABA within it, severely reduced kyphosis, increased nursing in more atypical postures, and had little or no effect on pronurturance. Various forebrain sites are known to mediate retrieval and licking of pups. Inhibition of dopaminergic activity in the nucleus accumbens of dams via microinfusions of a mixed D1/D2 dopamine receptor antagonist, cis-flupenthixol (FLU), dose-dependently reduced these active behaviors, while increasing nursing duration. Retrieval was inhibited, however, only by infusions of FLU that included the nucleus accumbens shell, which is reciprocally connected with other sites implicated in retrieval of pups. Thus, maternal behavior is not a unitary process but rather a complex category consisting of sequential behavioral components that have their own sensory and neural determinants.

Bone density loss after allogeneic hematopoietic stem cell transplantation: a prospective study.

The incidence and course of bone density abnormalities following hematopoietic stem cell transplantation are poorly understood and complicated by the impact of multiple factors. Hip, spine, and wrist bone mineral densities (BMDs) were measured in 104 adults (54 women, 54 men; mean age, 40 years [range, 18-64 years]) at 3 and 12 months after allogeneic transplantation. Clinical and laboratory variables were evaluated using univariate and multivariate analyses to determine risk factors for osteoporosis, fracture, and avascular necrosis. At 3 months posttransplantation, combined (male and female) hip, spine, and wrist z scores were -0.35, -0.42, and +0.04 standard deviations, respectively. At 12 months both men and women experienced significant loss of hip BMD (4.2%, P < .0001); changes in the spine and wrist were minimal. The cumulative dose and number of days of glucocorticoid therapy and the number of days of cyclosporine or tacrolimus therapy showed significant associations with loss of BMD; age, total body irradiation, diagnosis, and donor type did not. Nontraumatic fractures occurred in 10.6% of patients and avascular necrosis in 9.6% within 3 years posttransplantation. The decrease in height between pretransplantation and 12 months posttransplantation was significant (P = .0001). Results indicate that loss of BMD after allogeneic stem cell transplantation is common and accelerated by the length of immunosuppressive therapy and cumulative dose of glucocorticoid. An increased incidence of fracture and avascular necrosis may adversely impact long-term quality of life. Prevention of bone demineralization appears warranted after stem cell transplantation.

Acquiring simultaneous EEG and functional MRI.

OBJECTIVE: Electroencephalography (EEG) is a challenge to record simultaneously with functional MRI (fMRI), for it is prone to large artifacts induced by both the static and the time-variant fields of the MR scanner. However, truly concurrent EEG/fMRI recording has great potential for clinical and scientific neurological applications. We have devised a method for acquiring EEG simultaneously with fMRI that minimizes contamination of the EEG signals. METHODS: We recorded EEG differentially during fMRI using special twisted dual-lead electrodes in a bipolar montage, and a combination of analog pre-processing and digital post-processing of the EEG data. We implemented a functional scan protocol that typically yields artifact-free EEG over 87% of the MR scanning period. RESULTS: Our approach greatly reduced gradient, radio frequency, motion and ballistocardiographic artifact in the EEG, and allowed continuous monitoring of the EEG during functional scanning. To illustrate the quality of the EEG following post-processing, we demonstrated that EEG recorded during fMRI retains useful spectral information. CONCLUSIONS: Quality EEG may be recorded simultaneously with fMRI. With this union, activation maps could be made of any relevant changes in the EEG, such as inter-ictal spikes or spectral variations, or of evoked response potentials (ERPs).

Impact of a randomized, controlled trial of liberal vs conservative hospital discharge criteria on energy, protein, and fluid intake in patients who received marrow transplants.

OBJECT: To determine if adult patients who received marrow transplants had faster resumption of oral energy and nutrient intake and shorter duration of intravenous (i.v.) fluid requirement if discharged from the hospital earlier than is customary. DESIGN: Randomized, controlled trial of patients remaining hospitalized because of inadequate oral intake. Consenting patients were assigned randomly to remain hospitalized (hospital group) or be discharged to an ambulatory setting (ambulatory group). SUBJECTS: Seventy-eight patients of the Fred Hutchinson Cancer Research Center who were consuming less than 33% of estimated energy requirement and requiring up to 3,000 mL of fluids per day intravenously. INTERVENTION: Participants received nutrition counseling by a registered dietitian to promote resumption of oral intake. Daily oral intake records were analyzed to determine energy and nutrient content. MAIN OUTCOME MEASURES: Days after study enrollment to consume 33% of energy and protein requirements and total number of days of i.v. fluid support were analyzed by group until discharge from the center, approximately 100 days after transplantation. STATISTICAL ANALYSES: Demographic data were defined by group means. Differences between treatment procedures were determined by Cox regression analysis. No variables were confounding. RESULTS: The hospital group took fewer days than the ambulatory group to resume oral energy intake (4.5 vs 8.0, P = .004) and to discontinue i.v. fluids (30.5 vs 48.5, P = .019). There was no difference between groups in days of parenteral nutrition support (P = .817) or days to resume oral protein intake (P = .470). APPLICATIONS/CONCLUSIONS: Oral and gastrointestinal complications delay resumption of oral energy and protein intakes after transplantation. Earlier hospital discharge can achieve cost savings but may delay resumption of oral energy intake. Because of continued high-risk nutrition status and potential for rapid change in medical status, nutrition assessment and counseling are necessary in both the hospital and ambulatory setting to promote resumption of oral intake and discontinuation of i.v. fluids.

Maternal behavior stimulates c-fos activity within estrogen receptor alpha-containing neurons in lactating rats.

Estradiol and other hormones are thought to be critical for the onset, but not maintenance, of maternal behavior in rats. Maternal behavior is instead maintained postpartum by tactile stimulation that dams receive during interactions with pups, and many neural sites implicated in the control of maternal behavior show elevated c-fos activity in response to this stimulation. Many of these sites also contain neurons that express the alpha subtype of the estrogen receptor (ERalpha). Because of possible interactions between tactile stimulation from pups, c-fos, and ERalpha in the lactating rat brain, we determined if populations of cells that show increased c-fos activity after maternal behavior in lactating rats also contain ERalpha. Dams were separated from their pups for 48 h beginning on day 5 postpartum. On day 7 postpartum, experimental dams were reunited with pups and mother-litter interactions were observed for 60 min. Control dams received no pup stimulation. Subjects were sacrificed 60 min later and brain sections were double immunolabeled for the Fos and ERalpha proteins. As expected, the number of ERalpha-immunoreactive (ERalpha-ir) neurons did not differ between the two groups in the eight areas analyzed (lateral region of the lateral septum, posterodorsal medial amygdala, dorsal and ventral medial preoptic area, dorsal and ventral bed nucleus of the stria terminalis, lateral habenula, and ventrolateral caudal periaqueductal gray). Consistent with previous reports, maternal dams had 2- to 7-fold more Fos-immunoreactive (Fos-ir) neurons in these sites compared with nonstimulated controls. Maternal dams had significantly more Fos-ir neurons that also contained ERalpha-ir in all sites, with the greatest increases in the ventral medial preoptic area, lateral habenula, and ventral bed nucleus of the stria terminalis. Between approximately 25 and 45% of the Fos-ir cells in the sites examined also expressed ERalpha. Thus, a substantial number of neurons that are genomically activated during maternal behavior contain ERalpha, raising the possibility that the postpartum display of maternal behavior can be influenced by ERalpha activity.

Effects of low dosages of apomorphine on maternal responsiveness in lactating rats.

Lactating rats (day 7 +/- 1 postpartum) were observed during a 1-h reunion with their pups 4 h after separation from them and 10 min after subcutaneous injection of saline (SAL; 0.1 ml) or low dosages of the dopamine agonist, apomorphine (APO; 0.1 or 0.25 mg/kg). Although APO did not affect latency to sniff pups or retrieve the first pup, there were dosage-dependent delays in onset of licking and nursing pups, and decreases in retrieval and grouping of pups, nursing duration, and litter weight gain. The alterations in maternal responsiveness among APO-treated dams were related to increased carrying and mouthing of pups and markedly increased sniffing of pups, bedding, and cage. Duration of time spent licking pups, exploring, and self-grooming did not differ between groups. Thus, certain APO-induced stereotypic behaviors interfered with the normal sequence of maternal behavior by exaggerating some components and delaying others. These results are relevant to disturbances in maternal behavior caused by hyperreactivity or by other drugs that increase dopaminergic activity, such as cocaine.

Therapy with the elderly: introducing psychodynamic psychotherapy to the multi-disciplinary team.

Psychotherapy with the elderly has tended to be restricted to family or behavioural paradigms with some contribution from cognitive approaches, but at least until recently, very little input from psychodynamic therapy. The reasons for this are discussed and include both patient and therapist factors. Freud himself was pessimistic regarding the prospects of working with the elderly, a viewpoint he changed as he aged. As the discipline of old age psychiatry also matures there may be increasing scope for collaboration between the mental health of the elderly teams and psychodynamically orientated therapists. We describe here one model of such collaboration, a weekly case discussion seminar, conducted in an acute admission old age psychiatry in-patient unit. The role of the seminar in discussing difficult cases will be described and a case will be discussed to illustrate the work. Finally, recommendations for broadening the scope of the work are advanced.

Successfully implementing a performance-based compensation plan. The secret is in the development process.

A performance-based compensation plan can effectively turn around a troubled physician practice. While no one plan will work for all practices, a particular development and implementation process has proven successful for a number of them. The process involves an inclusive approach designed to achieve the highest possible level of consensus among the physicians, identification of appropriate performance criteria and development of incentives to produce the desired behaviors.

Dopamine receptor blockade in the nucleus accumbens inhibits maternal retrieval and licking, but enhances nursing behavior in lactating rats.

Maternal behaviors were recorded in rats after a 4-h dam-litter separation and intracranial microinfusion of saline on Day 6 postpartum or cis-flupenthixol (FLU), a dopamine (DA) receptor antagonist, on Days 7-9, within the nucleus accumbens (NA) or dorsomedial striatum (DMS) bilaterally (5, 10, or 20 micro/microL/side), or the lateral ventricle (LV) unilaterally (20 or 40 micro/microL). The number of pups retrieved was inhibited in a dosage-dependent manner by FLU within the NA, but not in other sites. Pup retrieval did not occur within 5 min after 20 microg FLU in five out of nine NA dams; only in these dams did infusions include the shell region of the NA. Duration of pup licking was dose dependently decreased by FLU, the most within the NA, and to a lesser extent within the DMS. Nursing behavior in the kyphotic (upright, dorsally arched) posture, initiated in the absence of pup retrieval by placing the dam over the gathered pups, was not inhibited by intracranial FLU in any site assessed, but rather lasted longer after FLU in NA dams. These various effects of FLU, especially in NA, may be related to modest increases in catalepsy.

Guaifenesin- and ephedrine-induced stones.

PURPOSE: We report a new type of drug-induced stone that is caused by overconsumption of preparations containing guaifenesin and ephedrine. MATERIALS AND METHODS: Clinical and stone analysis data from the Molecular Structure Laboratory at the Veterans Affairs Medical Center in Milwaukee, Wisconsin, were reviewed. Stone analysis was performed by Fourier transform infrared spectroscopy, high-resolution X-ray crystallographic powder diffraction, or both. The urine and stone material from one of the subjects were analyzed with high-performance liquid chromatography. RESULTS: Stone analysis from seven patients demonstrated metabolites of guaifenesin. High-performance liquid chromatography revealed that the stone and urine from one subject had a high content of guaifenesin metabolites and a small amount of ephedrine. Demographic data were available on five patients. Three had a history of alcohol or drug dependency. All were consuming over-the-counter preparations containing ephedrine and guaifenesin. Four admitted to taking excessive quantities of these agents, mainly as a stimulant. Hypocitraturia was identified in two individuals subjected to urinary metabolic testing. These stones are radiolucent on standard X-ray imaging but can be demonstrated on unenhanced CT. Shockwave lithotripsy was performed in two patients, and the calculi fragmented easily. CONCLUSIONS: Individuals consuming large quantities of preparations containing ephedrine and guaifenesin may be at risk to develop stones derived mainly from metabolites of guaifenesin and small quantities of ephedrine. These patients may be prone to drug or alcohol dependency.

Effects of unilateral suckling on nursing behavior and c-fos activity in the caudal periaqueductal gray in rats.

In rats, suckling elicits kyphosis-the bilaterally symmetrical, upright, humpbacked nursing posture-and maximal expression of the immediate early gene c-fos in a region of the caudal periaqueductal gray (cPAG) that mediates the sensorimotor integration of kyphosis. We determined the effects of prepartum unilateral nipple removal on nursing behavior and c-fos expression during a 60-min mother-litter interaction on Day 7 postpartum. Compared with dams suckled by 6 pups bilaterally, dams suckled unilaterally displayed essentially normal maternal behaviors, including kyphosis. Unilaterally suckled dams, however, showed an increase in the abnormal prone nursing posture, a decrease in proportion of kyphotic nursing of total time over pups, and a 20% higher contralateral/ipsilateral ratio of cPAG neurons expressing c-fos. These results are consistent with an incompletely lateralized neural pathway conveying suckling stimulation to the cPAG and provide a mechanism whereby kyphosis is elicited by unilateral suckling when pups initiate nursing from their supine dam.

Maternal motivation of lactating rats is disrupted by low dosages of haloperidol.

Motorically-active maternal behaviors of rats, such as retrieval and licking of pups, are known to be reduced or suspended following systemic injection of > or = 0.2 mg/kg haloperidol (HAL), a dopamine (DA) receptor blocker. Further, when these behaviors are thwarted by muzzling, dams persistently attempt to make snout contact with pups by pushing them with the muzzle, indicative of intense maternal motivation. To evaluate whether time spent contact-seeking by muzzle-pushing is impaired by dosages of HAL too low to reduce retrieval and licking of pups, dams were fitted with a full muzzle (FM), given 0, 0.05 or 0.10 mg/kg HAL, and reunited with their pups for 30 min after a 4-h separation. Similarly-treated dams fitted with a control muzzle, which allows perioral contact with pups, displayed essentially normal maternal behavior. In FM dams, low dosages of HAL severely and dose-dependently reduced muzzle-pushing, as well as actual contact by handling-touching and moving pups with their paws, although the latency to initiate these behaviors by responders was not impaired. A threshold level of DA is apparently necessary for efficient motor control (handling) and for maternal incentive, persistent effort to achieve contact with pups (muzzle-pushing), consistent with an arousal explanation of the action of DA.