A seismic reflection image for the base of a tectonic plate.

Plate tectonics successfully describes the surface of Earth as a mosaic of moving lithospheric plates. But it is not clear what happens at the base of the plates, the lithosphere-asthenosphere boundary (LAB). The LAB has been well imaged with converted teleseismic waves, whose 10-40-kilometre wavelength controls the structural resolution. Here we use explosion-generated seismic waves (of about 0.5-kilometre wavelength) to form a high-resolution image for the base of an oceanic plate that is subducting beneath North Island, New Zealand. Our 80-kilometre-wide image is based on P-wave reflections and shows an approximately 15° dipping, abrupt, seismic wave-speed transition (less than 1 kilometre thick) at a depth of about 100 kilometres. The boundary is parallel to the top of the plate and seismic attributes indicate a P-wave speed decrease of at least 8 ± 3 per cent across it. A parallel reflection event approximately 10 kilometres deeper shows that the decrease in P-wave speed is confined to a channel at the base of the plate, which we interpret as a sheared zone of ponded partial melts or volatiles. This is independent, high-resolution evidence for a low-viscosity channel at the LAB that decouples plates from mantle flow beneath, and allows plate tectonics to work.

Geophysical investigations of the tectonic boundary between East and west antarctica.

The Transantarctic Mountains (TAM), which separate the West Antarctic rift system from the stable shield of East Antarctica, are the largest mountains developed adjacent to a rift. The cause of uplift of mountains bordering rifts is poorly understood. One notion based on observations of troughs next to many uplifted blocks is that isostatic rebound produces a coeval uplift and subsidence. The results of an over-snow seismic experiment in Antarctica do not show evidence for a trough next to the TAM but indicate the extension of rifted mantle lithosphere under the TAM. Furthermore, stretching preceded the initiation of uplift, which suggests thermal buoyancy as the cause for uplift.

Osteoporosis and pathologic fractures in anorexia nervosa.

Osteoporosis with pathologic fractures occurred in three patients with chronic anorexia nervosa. The authors discuss the pathophysiology of this rarely reported complication and advise clinicians to thoroughly investigate complaints of bone or back pain from this high-risk population.

Case report of cardiovascular abnormalities in anorexia nervosa.

The authors report the case of a young woman with anorexia nervosa who had a profound bradyarrhythmia and coagulopathy. They present guidelines for medical evaluation of all patients with anorexia nervosa and criteria for hospitalization.

Psychiatric management of acute myocardial infarction in the coronary care unit.

Failure to recognize and treat the psychiatric complications of myocardial infarction (MI) may aggravate the underlying cardiac condition and interfere with its treatment. The timing and manifestations of several distinct psychiatric conditions that commonly accompany the acute phase of MI (anxiety, depression, delirium, and behavioral abnormalities secondary to a person's premorbid character style) will be reviewed. In addition, the importance of psychological risk factors for the development of coronary artery disease (e.g., life stress and the Type A behavior pattern) and the impact of denial on the cardiac patient's condition will be discussed. Management strategies that include nonpharmacologic (i.e., support, reassurance, brief psychotherapy and cardiac rehabilitation) and psychopharmacologic interventions (e.g., the rational use of benzodiazepines, antidepressants and neuroleptic agents) for psychiatric conditions in the MI patient will be provided. Postdischarge issues that occur in both the patient and his or her family are outlined, and the enrollment in cardiac rehabilitation programs is encouraged.

Continuous infusion of physostigmine in anticholinergic delirium: case report.

A continuous intravenous infusion of physostigmine was successfully used in the management of a case of anticholinergic poisoning. In selected patients, intravenous physostigmine can be a safe and specific means of reversing the signs and symptoms of anticholinergic toxicity.

Treatment of attention deficit and borderline personality disorders with psychostimulants: case report.

A case is reported of a young woman with attention deficit disorder and concomitant borderline personality disorder who was successfully treated with methylphenidate. The overlapping criteria for these disorders are discussed and recommendations for treatment with psychostimulants are suggested.

Non-lithium-induced renal failure with secondary lithium toxicity: case reports.

Two manic-depressive patients are described who presented with acute renal failure and concurrent lithium toxicity. In both cases the etiology of the renal failure was not a direct result of the use of lithium. Controversy concerning the nephrotoxicity of lithium is discussed, and recommendations for the evaluation of renal failure during lithium therapy are provided.

Renal disease and dysfunction in two patients with anorexia nervosa.

Two patients are described who illustrate the association between renal abnormalities and eating disorders. The relevant literature is reviewed, and the difficulty in managing these patients on medical and surgical services is highlighted.

Benztropine prophylaxis of dystonic reactions.

The effectiveness of antiparkinson medication for the prevention of drug induced dystonias has remained a question. Forty patients with acute psychosis who received high potency oral antipsychotic drugs were interviewed to determine the incidence of acute dystonia. An eleven-fold increase in dystonia was found in patients who received no prophylactic medication. Such prophylaxis appears effective in preventing acute dystonia.

Successful treatment of acquired Tourettism and major depression.

The authors report a successfully treated case of an 81-year-old man with acquired Tourettism and secondary depression. Organic causes of acquired Tourettism are reviewed and treatment strategies are discussed.

Failure to record delirium as a complication of intra-aortic balloon pump treatment: a retrospective study.

This study was conducted to determine whether or not diagnosis and treatment of delirium among patients treated with the intra-aortic balloon pump (IABP) correlates with the recording of this complication on discharge records. Since prior episodes of delirium are one of the few clear risk factors for future episodes of delirium, accurate recording of delirium on the discharge summary and list of discharge diagnoses is useful to clinicians. A retrospective review of the charts of all patients (N = 198) who underwent placement of an IABP during 1988; assessment of the type and frequency of medical and neuropsychiatric complications during IABP treatment; and comparison of chart review findings with the Massachusetts General Hospital's computer-generated lists of discharge diagnoses for the same IABP-treated patients was completed. Only 12% of patients diagnosed and treated for delirium had delirium recorded as a discharge diagnosis. In contrast, 44% and 52% of patients who had been diagnosed and treated for cerebrovascular accident and pneumonia, respectively, had these diagnoses recorded among the discharge diagnoses. Receiving a discharge diagnosis of organic brain syndrome increased the likelihood that delirium was recorded as a discharge diagnosis. Delirium is underdiagnosed as a complication associated with IABP-treatment and is under-reported on the list of discharge diagnoses, even when it is diagnosed. Further study is warranted to determine if making the diagnosis of delirium during a patient's hospital course and recording it is a complication at the time of discharge is translated into a higher level of preparedness by physicians during subsequent hospitalizations.

Depression and diabetic neuropathy: a complex relationship.

In a group of 64 non-insulin-dependent diabetic females, a significant positive correlation between Zung self-rated depression scores and objective measurements of diabetic peripheral neuropathy was limited to those women with Zung scores greater than 50 (depressed group, n = 12). In the overall group, there was no significant linear or quadratic relationship between peripheral neuropathy and depression scores. The associations between depression, peripheral neuropathy, and diabetes are discussed.

Management of the prescription-drug-dependent adult: case of meprobamate abuse and its treatment.

Misuse of prescription drugs in the elderly can be a serious problem that is difficult to manage. Prescriptions for non-narcotic central nervous system (CNS) depressants (e.g., anxiolytics and sedative-hypnotics) are commonly written, and their use is associated with severe intoxication and withdrawal effects. The presence of comorbid psychiatric conditions (e.g., depression or panic disorder), for which these agents are prescribed frequently, complicates the clinical picture. This paper, using case examples of meprobamate abuse, describes how physicians can recognize, manage, and treat a patient who is abusing a non-narcotic CNS depressant.

Pros and cons of fluoxetine for the depressed cancer patient.

When major depression develops in patients with cancer, specific antidepressant treatment should be initiated. Fluoxetine (Prozac) is one of several effective treatments for depression; it is currently the most frequently prescribed antidepressant in the United States. Unfortunately, the information from studies and reports regarding the use of fluoxetine in patients with cancer is limited. This article reviews the properties, drug interactions, and side-effect profiles of fluoxetine and the other antidepressants most relevant to the care of cancer patients. Also discussed are strategies for the prudent prescription of fluoxetine, the tricyclic antidepressants, and the psychostimulants in depressed cancer patients.

Management of delirium associated with use of the intra-aortic balloon pump.

Five patients who developed an agitated delirium in association with use of an intra-aortic balloon pump are presented. The differential diagnosis of delirium in critically ill cardiac patients is reviewed and effective pharmacologic treatment strategies (involving rapid and aggressive management with intravenous haloperidol) are discussed.

Treatment of anxiety associated with electrophysiologic studies.

Programmed electrical stimulation, also known as electrophysiologic studies (EPS), is a cardiologic technique used to help guide physicians in their management of selected patients with cardiac arrhythmias. Data are presented for 14 consecutive patients undergoing EPS seen in psychiatric consultation who had a diagnosis related to anxious mood. Successful management strategies, which evolved from work with these patients, included psychologic approaches (supportive psychotherapy and education) and psychopharmacologic agents (most commonly alprazolam). EPS and related physiologic aspects of anxiety and stress are briefly reviewed.

Identification of patient-generated feelings in security personnel.

Several authors have pointed out that the recognition of feelings aroused by patients in health professionals can be useful in the delivery of patient care. The general hospital setting provides an in vivo research laboratory for studying the awareness of patient-generated feelings. A questionnaire designed to help categorize and quantify the feelings experienced by security personnel (N = 28 males) while working with patients at the Massachusetts General Hospital indicated that security personnel experience a wide variety of emotions as a result of their contact with patients. Fear, anxiety, and helplessness were reported by the majority. The preponderance of negative affects identified confirms the stressful nature of their work.