Alpha-7 and alpha-4 nicotinic receptor subunit immunoreactivity in genioglossus muscle motoneurons

In the present study, immunohistochemistry combined with retrograde labeling techniques were used to determine if hypoglossal motoneurons (HMNs), retrogradely labeled after cholera toxin B subunit (CTB) injection to the genioglossus muscle in rats, show immunoreactivity for alpha-7 and alpha-4 subunits of nicotinic acetylcholine receptors (nAChRs). CTB-positive HMNs projecting to the genioglossus muscle were consistently labeled throughout the rostrocaudal extent of the hypoglossal nuclei with the greatest labeling at and caudal to area postrema. Alpha-7 subunit immunoreactivity was found in 39.44+/-5.10% of 870 CTB-labeled motoneurons and the alpha-4 subunit in 51.01+/-3.71% of 983 CTB-positive neurons. Rostrally, the number of genioglossal motoneurons demonstrating immunoreactivity for the alpha-7 subunit was 45.85+/-10.04% compared to 34.96+/-5.11% at and caudal to area postrema (P>0.1). The number of genioglossal motoneurons that showed immunoreactivity for the alpha-4 subunit was 55.03+/-4.83% at and caudal to area postrema compared to 42.98+/-3.90% in rostral areas (P=0.074). These results demonstrate that nAChR immunoreactivity is present in genioglossal motoneurons and suggest a role for alpha-7 and alpha-4 subunits containing nAChRs in the regulation of upper airway patency.

Managing pain: The Challenge in Underserved Populations: Appropriate Use Versus Abuse and Diversion

ISSUE

Inadequate pain management is a serious public health problem that affects a wide cross-section of Americans. Patients are often denied sufficient medication, because physicians lack training and fear scrutiny from federal and state regulatory agencies. In addition, even the state-financed system of care, Medicaid, has been increasingly denying payment for the best treatment for pain management. These factors are complicated by physician bias about various subgroups and poor physician-patient communication. Comprehensive patient assessment plays a crucial role in determining appropriate treatment and identifying potential abuse problems. Physicians must routinely document medications analgesic effects and screen for potential ill effects and drug abuse.

OBJECTIVE

To examine the prevalence of the undertreatment of pain, particularly among African Americans, and to recommend relevant proactive policy and practice changes to aid in eliminating this health problem.

CONSENSUS PROCESS

In July 2002, the NMA convened the "Managing Pain: The Challenge in Underserved Populations: Appropriate Use versus Abuse and Diversion" Consensus Meeting in Washington, DC. The country's most renowned experts in the area of pain management and substance abuse reviewed substantial information regarding pain management and substance abuse including the following: --A draft summary paper on pain management and substance abuse that served as briefing material for consensus members; --Annotated bibliographies; --Articles on pain management and substance abuse; and --Key presentations on pain management and substance abuse.

Expression of α-7 nAChRs on spinal cord–brainstem neurons controlling inspiratory drive to the diaphragm

In the present study, we determined whether alpha-7 subunit containing nicotinic acetylcholine receptors (nAChRs) are expressed by neurons within the pre-Botzinger complex (pre-BotC), bulbospinal, and phrenic motor nuclei in the rat. alpha-7 Immunohistochemistry combined with cholera toxin B (CTB), a retrograde tracer was used to detect expression of alpha-7 nAChRs by phrenic motor and bulbospinal neurons. Neurokinin-1 receptor immunoreactivity was used as a marker for pre-BotC neurons. Of the CTB-positive neurons in the phrenic nuclei, 60% exhibited immunoreactivity for alpha-7 nAChRs. Of the bulbospinal neurons in the paramedian reticular nuclei (PMn), gigantocellular nuclei (Gi), raphe nuclei, rostral ventrolateral medulla (RVLM) and nucleus tractus solitarius, 20-50% were found to express alpha-7 nAChR immunoreactivity. Of the peudorabies virus (PRV) labeled bulbospinal neurons in PMn, Gi, raphe and RVLM, 9-12% co-expressed alpha-7 nAChRs. Immunoreactivity for alpha-7 nAChRs was also detected in 57% of the neurokinin-1 receptor containing neurons presumed to reside in pre-BotC. These findings suggest that nicotinic cholinergic regulation of the chest wall pumping muscles may occur at multiple levels of the central nervous system.

Tobacco control: consensus report of the National Medical Association

ISSUES

Tobacco Control remains one of the greatest determinants for reducing the morbidity and mortality of African Americans.

OBJECTIVE

To examine the scope and consequences of tobacco use among African Americans and characterize its implications for the National Medical Association physician membership and their patients, and identify policy, education, advocacy and research issues in Tobacco Control for the organization.

CONSENSUS PROCESS

Literature review using the MEDLINE database from January 1966 to August 1999 Week 1, searching Medical Subject Heading (MeSH) reading combined with text words "Black" or "African American" and "Tobacco" as a search term, identified 130 articles/110 abstracts published between 1988 and February 1999. The panel selected 61 appropriate articles and a paper summarizing the literature review was developed. The summary paper was used as background material for a formal consensus panel discussion on July 16-17, 1999. Consensus among committee members was reached via mail, fax and e-mail using the summary review paper, annotated bibliographies key informant surveys, and previous NMA resolutions on tobacco control. A formal working session was held on July 16-17, 1999 in which four areas of concentration of issues were determined: Policy, Advocacy, Education and Research. All committee members approved the final report.

SUMMARY

Because tobacco control issues in African Americans are both complex and poorly understood, the panel views the NMA's role as pivotal in the coordination of resources and capacity-building to address all four areas identified. Stronger partner-ships with traditional federal and nonprofit agencies associated with tobacco control/advocacy in African Americans as well as nontraditional organizations (i.e., churches, academia, marketing and media organizations) also must occur to strengthen the infra-structure needed to assess needs, design appropriate interventions and evaluate the appropriateness, effectiveness and efficacy of tobacco control efforts in African American communities.

Synergism between cocaine and atropine at the caudal ventrolateral medulla of cats

We have previously reported that the anticholinergic properties of cocaine may be important in cocaine induced apneusis. We have studied the effects of the cholinergic muscarinic antagonist atropine (ATR) on cocaine induced apneusis at the caudal chemosensitive areas of the ventrolateral medulla oblongata (CVLM). Experiments were performed in urethane anesthetized and tracheotomized cats with the CVLM surgically exposed. Topical application of ATR (44 mM ) to the CVLM produced significant decrements in minute ventilation (V(E)) and mean arterial blood pressure (MABP) (P<0.05) but the effects on tidal volume (V(T)), respiratory frequency (f) and heart rate (HR) were not significant. Administration of cocaine (37 mM) to ATR pretreated animals increased the incidence of cocaine induced respiratory arrest to more than twofold greater than when cocaine was administered in the absence of pretreatment. The ATR pretreated animals that did not experience inspiratory arrest after cocaine were shown to exhibit significant decrements in f and V(E) as a consequence of prolonged inspiratory pauses. The reduction in MABP after cocaine in ATR pretreated animals was also significant. These results suggest that ATR enhances the central respiratory toxicity of cocaine by acting synergistically at CVLM chemosensitive sites.

Racism in medicine: planning for the future

African Americans and other minority populations have not benefited to the same degree as the majority of Americans from the advances in health care in our country. The vestiges of racism have resulted in inequities which exist in training, medical practice, medical decision making, the work environment and biomedical research. Recommendations are made to eliminate racial and ethnic bias in healthcare through monitoring and increasing the number and the distribution of medical trainees proportionate to the diversity of the U.S. population; through improvements in the medical school curriculum to include the impact of race and ethnicity on healthcare outcomes as well as the effect of physicians' attitudes on health; through the inclusion of an adequate number, mix and distribution of health care professionals relative to the diversity of the participants in health plans with due process for patients and physicians; and through increased participation in peer review research funding, training and as subjects in biomedical research directed to improve the quality of healthcare for diverse populations.

Somatosensory evoked potential, neurological examination and magnetic resonance imaging for assessment of cervical spinal cord decompression

The present study was designed to determine the relationship between neurological testing, anatomical imaging, and electrophysiological monitoring for assessing outcome of cervical spinal cord decompression. We prospectively studied 28 consecutive patients (age 39-76 yr) who were subjected to presurgical-(1-3 wk) and postsurgical (3-4 mo) neurological examination and recording of the median nerve somatosensory evoked potential (SEP). In 13 patients, magnetic resonance imaging (MRI) was also performed. Changes in neurological function, SEP and MRI were evaluated and graded as (1) improvement,(2) no change or (3) deterioration. Neurological outcome (NO) was based on changes in motor grade strength, sensory, reflexes and gait. The SEP outcome was based on changes in latency and disappearance of SEP waveform components whereas MRI evaluation was based on changes in spinal cord and canal diameters. Significance of association between NO, SEP and MRI was determined by Pearson's Chi-Square statistic (P<.05). The SEP improved in 71% (20/28) and deteriorated in 28% (8/28) of the subjects. An association between SEP changes and NO was found in 82% (23/28) of the subjects (P = .0038). Decompression increased the spinal canal diameter in 92% (12/13), and the spinal cord diameter in 38% (5/13) of the subjects. An association between NO, or SEP and MRI was not detected. Changes in median nerve SEP latency appear to be predictive of the neurological status of patients subjected to cervical spinal cord decompression. Postoperative increments in SEP latency or disappearance of the SEP waves were indicative of poor outcome after surgical decompression of the cervical spinal cord.

Analgesic responses to intrathecal morphine in relation to CSF concentrations of morphine-3,beta-glucuronide and morphine-6,beta-glucuronide

This study was performed to determine whether variations in analgesic responses to intrathecal morphine could be explained by cerebrospinal fluid (CSF) concentrations of morphine metabolites. Twenty-four CSF samples were collected at the beginning, middle and end of treatment periods in seven cancer patients with pain of malignant origin. CSF concentrations of morphine-3,beta-glucuronide (M3G) and morphine-6,beta-glucuronide (M6G) metabolites were measured by gas chromatography/mass spectrometry. Analgesic responses to morphine were estimated concurrent with CSF collection using a visual analog scale representing percentages of pain relief. Effective analgesia was defined as > or = 75% pain relief. CSF concentration of M3G and M6G in the 24 samples were 722 +/- 116 ng/ml and 699 +/- 158 ng/ml, respectively. CSF samples were categorized into two groups: (1) those collected during effective analgesia (N=14), and (2) those collected during ineffective analgesia (N=10). M6G levels detected in group 1 samples (effective analgesia) were significantly greater than those found in group 2 samples (ineffective analgesia) (978 +/- 243 ng/ml vs 309 +/- 68 ng/ml, P<0.05). Intergroup differences in CSF M3G concentrations and M3G/M6G ratios were not significant. It is concluded that CSF M6G may be indicative of effectiveness of analgesia in cancer patients subjected to intrathecal morphine.

Subarachnoid hemorrhage in the African-American population: a cooperative study

The clinical outcome of patients following subarachnoid hemorrhage is complicated by delayed cerebral ischemia and contributing factors such as hypertension. To observe the impact of hypertension and delayed cerebral ischemia on the outcome of a predominantly African-American cohort following subarachnoid hemorrhage, both retrospective (n = 42) and prospective (n = 21) studies were conducted. In the total pool (n = 63), the mean age was 49.7 years (range: 17 to 80) with a preponderance of female patients (70%). Aneurysm formation was significant in the region of the posterior communicating artery. Of the patients reviewed, 73.8% had preexisting hypertension and 45.9% developed delayed cerebral ischemia. Approximately 89% of the patients who suffered from delayed cerebral ischemia had hypertension. Results failed to display any significant beneficial association between the use of the calcium channel blocker nimodipine and delayed cerebral ischemia. Use of the antifibrinolytic drug aminocaproic acid demonstrated a worse patient outcome. It is not recommended that aminocaproic acid be used in this population. Subsequently, due to the proportional occurrence of delayed cerebral ischemia in hypertensive patients following subarachnoid hemorrhage, it is suggested that prophylactic surgical management of unruptured intracranial aneurysms be considered in hypertensive patients. Further study is needed to discern the association between hypertension, delayed cerebral ischemia, and stroke in patients following subarachnoid hemorrhage.

Monitoring of median nerve somatosensory evoked potentials during cervical spinal cord decompression

We evaluated the intraoperative utility of monitoring median nerve somatosensory evoked potentials (SEPs) in 31 consecutively hospitalized neurosurgical patients (mean age 55.3 +/- 2.1 years) who underwent spinal cord decompression for cervical herniated disc, spondylosis, or tumor. Pre- and postoperative standard neurological examinations included evaluation of motor function, sensory responses, gait, tone, and reflexes. Evoked potentials were recorded from clavicular Erb's (N9) and contralateral cortical (N20) points. Intraoperatively, SEP measurements were obtained after the onset of anesthesia (baseline control) and were repeated throughout the operative procedures. N20 and N9-N20 conduction latencies were measured for each SEP recording; disappearance of the SEP waveform was interpreted as a nonquantifiable increase in latency. Follow-up neurological examinations were made immediately after and up to 6 months following surgery. Postoperatively, the 31 study subjects were assigned to one of two groups based on neurological evaluation: 27 group I subjects had either no change or improvement (good outcome) whereas four group II subjects had postoperative neurological deterioration (poor outcome). Intraoperative N9-N20 interpeak latency was found to increase during cervical decompression in six of 27 group I and in two of four group II subjects. Only two of the Group I subjects exhibited increases > 10% (14 and 19%, respectively). Intraoperative communication to the surgeon of a marked increase of N9-N20 latency during positioning for cervical traction clearly obviated a poor outcome in one group I subject; Upon removal of traction, latency decreased and significant changes in neurological function were not detected postoperatively. The SEP waveform disappeared in two of the group II and in none of the group I subjects. In the two group II subjects exhibiting increases of N9-N20 latencies, increments were > 20%. These findings indicate that in patients undergoing cervical spinal cord decompression, disappearance of SEPs or increases > 20% in the N9-N20 interpeak latency are suggestive of operative conditions that place patients at risk for poor neurological outcome.

Effects of cholinomimetics on cocaine-induced hypotension and apneusis at a ventral brainstem cardiorespiratory control site

The current study was undertaken to evaluate the effects of cholinomimetic drugs on cocaine-induced central cardiorespiratory depression. Cats anesthetized by urethane (2.0 g/kg) were subjected to topical application at the caudal ventrolateral medullary surface (cVMS) of cocaine and two cholinomimetic pretreatment drugs. The following drug regimens were tested: 37 mM cocaine 1) given alone; 2) given 5 min after 2.7 mM carbachol pretreatment; and 3) given 5 min after 3.6 mM physostigmine pretreatment. In 7 of 11 cats, pretreatment with physostigmine decreased the incidence of cocaine-induced apneusis and hypoventilation significantly (p < 0.05); these animals showed no significant change in the mean arterial blood pressure during the 5-min pretreatment before administration of cocaine. In 4 of 11 cats, the physostigmine pretreatment produced a significant decrease in mean arterial blood pressure followed by lethal cardiorespiratory arrest when cocaine was administered. Pretreatment with carbachol resulted in cardiorespiratory responses which were not significantly different from those produced by cocaine alone. In anesthetized cats not exhibiting hypotensive responses to physostigmine, pretreatment may ameliorate cocaine-induced respiratory failure by ventral brainstem control mechanisms.

Central cocaine neurotoxicity at brainstem cardiorespiratory control sites

Cocaine hydrochloride was applied topically to the ventrolateral medullary surface (VMS) where chemosensitive respiratory and vasomotor control sites are colocalized. Cats (n = 16) were anesthetized with urethane (2.0 g/kg, 80 percent of dose titrated over 60 min). The trachea of each animal was cannulated and the VMS was surgically exposed. Tidal volume (VT), frequency of breathing (f), systolic and diastolic blood pressure (SBP and DBP, respectively), and heart rate (HR) were measured. Cocaine (62.5 micrograms per site) administered at the VMS control sites decreased f, SBP, and DBP significantly (p < 0.05), without changing HR or VT values. This cocaine-induced hypoventilation was associated with brief intervals of inspiratory cramp (apneusis). Central cocaine neurotoxicity may result from interaction of cocaine with VMS sites, producing increased inspiratory drive and decreased vasomotor tone.

Long-term Intraventricular Infusion of Morphine for Intractable Pain in Cancer of the Head and Neck

The authors' experience with seven patients with intractable pain that was treated by continuous intraventricular infusion of morphine through an implanted Infusaid pump is reported. The pain was caused by head and neck cancer in six patients and was associated with postpolio syndrome in one. The average follow-up was 7 months. Pain was effectively managed through intraventricular administration of a combination of morphine and mild oral narcotic analgesics. Complications included one case of transient respiratory depression, one pump pocket infection, and one pump failure. The morphine dose required to maintain analgesia increased over time in all patients treated. This is a safe and effective method of pain management in patients with head and neck cancer. It is useful as well in patients who have intractable pain that cannot be managed through an intrathecal route because of a contraindication to lumbar puncture or an inaccessible subarachnoid space.

Long-term intraventricular infusion of morphine for intractable pain in cancer of the head and neck

The authors' experience with seven patients with intractable pain that was treated by continuous intraventricular infusion of morphine through an implanted Infusaid pump is reported. The pain was caused by head and neck cancer in six patients and was associated with postpolio syndrome in one. The average follow-up was 7 months. Pain was effectively managed through intraventricular administration of a combination of morphine and mild oral narcotic analgesics. Complications included one case of transient respiratory depression, one pump pocket infection, and one pump failure. The morphine dose required to maintain analgesia increased over time in all patients treated. This is a safe and effective method of pain management in patients with head and neck cancer. It is useful as well in patients who have intractable pain that cannot be managed through an intrathecal route because of a contraindication to lumbar puncture or an inaccessible subarachnoid space.

Management of intractable pain in cancer patients by implantable morphine infusion systems

Ten patients underwent implantation of intrathecal morphine catheters with subcutaneous implantation of morphine Infusaid pumps for the treatment of intractable pain of malignant origin from May 1984 to October 1985. All patients exhibited a good initial response to intrathecal morphine and developed some degree of tolerance. All patients with bony metastasis and/or lumbarsacral plexopathy developed rapid tolerance.Depressive illness was noted in all patients undergoing a psychiatric evaluation prior to institution of morphine infusion therapy. Seventy percent of patients treated could be treated on an outpatient basis after pump implantation.Complications included a pump pocket infection requiring the removal of the implanted system. There was no pump failure, respiratory depression, urinary retention, or mortality related to the use of the morphine infusion system. It is recommended that intrathecal morphine infusion be instituted when narcotics have been identified as necessary for pain relief, before the development of significant systemic tolerance.

The Infusaid pump in the management of intractable cancer pain

At Howard University Hospital, nine terminally ill cancer patients with chronic pain have been treated with continuous intrathecal infusion of morphine delivered by the implantable Infusaid pump. The case of a patient treated at Howard University Hospital with this method of pain management is presented. Following Infusaid pump insertion, the patient lived for 22 months and obtained substantial relief of his cancer pain with no adverse side effects.

The management of increased intracranial pressure in children

Ten children with acute increased intracranial pressure, documented by the Cheek screw technique, were treated for Reye's syndrome, other toxic/metabolic encephalopathies, encephalitis, and traumatic encephalopathies. The rationale for the use of hyperventilation, head position, maintenance of adequate cerebral perfusion pressure, hyperosmolar agents, steroids, adequate fluid balance, and barbiturates in the therapy of these patients is described. An analysis of these cases reveals that early monitoring of intracranial pressure, maintenance of adequate cerebral perfusion pressure, and aggressive treatment of increased intracranial pressure may reduce the mortality of patients with increased intracranial pressure. Of all patients studied, those who survived demonstrated some neurological deficit as determined by clinical examination or neuropsychological testing.

Device for extradural monitoring of intracranial pressure: technical note

An ICP-monitoring device utilizing an extradural method is described. Clinical and laboratory use has shown it to be easily installed, safe, accurate, and reliable. It can be used with currently available transducers and monitoring equipment. It is hoped that this simple device will encourage the increased use of ICP monitoring.