The effects of growth hormone (GH)-releasing peptides on GH secretion in perifused pituitary cells of adult male rats.

The present study investigated the GH secretory activities of two distinctively different peptides: human pancreatic GH-releasing factor 44 (GRF-44) and a synthetic peptide His-DTrp-Ala-Trp-DPhe-Lys-NH2 (GHRP). GH secretion was studied in perifused dispersed anterior pituitary cells from male rats 24 or 48 h postdispersion. GRF-44 was 60 times more potent than GHRP and elicited linear increases in GH secretion between 0.3 and 30 ng (0.06-6 pmol), whereas the GHRP dose range was 3-300 ng (3.44-344 pmol). Hourly pulses of GHRP (30 ng) and GRF-44 (12.5 ng) stimulated consistent GH responses. An apparent priming effect was observed with GRF-44 at a dose of 3 ng. Continuous infusion of either peptide resulted in desensitization, with GH secretion being monophasic during GHRP infusion and biphasic during GRF-44 infusion. These results demonstrate that GRF-44 and GHRP, two peptides that have striking differences in their structure and size, stimulate in vitro GH secretion with remarkable similarity. However, the differences in potency, slope of the dose response, and pattern of GH secretion during continuous GRF-44 or GHRP infusion suggest that each stimulates in vitro GH secretion by slightly different mechanisms. GHRP or similar synthetic peptides may be useful probes to study GH secretory mechanisms.

Dose-response characteristics of various peptides with growth hormone-releasing activity in the unanesthetized male rat.

The characterization of GH-releasing peptides in vivo has been complicated by the effects of endogenous hypothalamic regulation of GH secretion. We describe a model to minimize endogenous hypothalamic interference by pretreating adult male rats with iv diethyldithiocarbamate and antisomatostatin serum. This pretreatment regimen established stable, detectable basal levels of plasma GH and eliminated spontaneous GH pulses for 12 h. Repeated pulsatile administration of 400 ng/kg iv rat hypothalamic GH-releasing factor (rGRF) produced consistent GH responses. Linear, nearly identical, dose responses (from 300-5000 ng/kg) were observed with rGRF and human pancreatic GH-releasing factor (GRF44) with ED50 values of 1059.3 and 1116.9 ng/kg, respectively. We also investigated a synthetic hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (GHRP), which was previously reported to have potent GH-releasing activity. In contrast to either rGRF or GRF44, repeated administration of the same dose of GHRP did not produce consistent GH responses. The first bolus of GHRP produced a larger GH pulse than the second (P less than 0.01), followed by increasing GH responses from injections 2 to 7. GHRP was about 2 log orders less potent than either rGRF or GRF44 on a molar basis. The disparity between the native peptides and GHRP suggests that the synthetic peptide may act to release GH through a different mechanism(s). In summary, these data indicate that the diethyldithiocarbamate/anti-somatostatin serum-treated animal may be a useful model for investigating the pituitary actions of GH-releasing peptides.

Cysticercosis cerebri. Review of 127 cases.

We reviewed the clinical features, diagnosis, and treatment in 127 cases of cysticercosis cerebri. The chief syndromes were seizures (55.1%), hydrocephalus (37.8%), and stroke (11.8%). Serum or CSF indirect hemagglutination titers, determined in 101 patients, were positive in 84.1% of those with CSF pleocytosis but in only 42.1% of those without. Computed tomography (CT), employed in 85 patients, showed typical multiple calcifications in 64.7%. The CT scans were most useful in the surgical treatment of ventriculomeningeal infestation. Ventricular shunt implantation was performed in 40 patients with hydrocephalus and produced marked improvement in 32. Cyst resection was necessary only for patients with rapidly enlarging fourth ventricle cysts.

Adult-onset temporal lobe epilepsy associated with smoldering herpes simplex 2 infection.

A 40-year-old man with chronic genital herpes simplex infection developed partial complex temporal lobe seizures of insidious onset, with EEG and MRI evidence of a unilateral temporal lobe destructive, atrophic process. Extensive workup did not reveal an infectious etiology. Three years of escalating number and severity of daily seizures with memory loss led to temporal lobectomy. Histologic study revealed active, low-level viral infection in the resected hippocampus and temporal lobe cortex, with immunohistochemical evidence for infection by herpes simplex 2, principally in neurons. In situ hybridization confirmed the presence of herpes simplex virus in neurons. Anticonvulsant-resistant seizure episodes began to recur several times daily soon after surgery, but the addition of acyclovir to the treatment regimen resulted in a substantial reduction in seizure occurrence, maintained for the subsequent 2.5 years.

Visual anomia: a unidirectional disconnection.

A right-handed patient with a complete right homonymous hemianopia could not name objects seen in her left hemifield but could always select an object from an assortment when the object was named. If the right hemisphere was devoid of auditory language function, we must postulate separate transcallosal pathways from visual to verbal and from auditory language to visual information. Because only the former pathway was interrupted, our patient exhibited a "unidirectional" disconnection.

Carotid occlusion in cysticercosis.

A man without orthostatic hypotension had transient ischemic attacks that were initiated by upright posture. CT showed a cystic mass in the interhemispheric fissure and basilar cisterns. Cerebral angiography demonstrated supraclinoid occlusion of the right internal carotid artery. At frontal craniotomy, cysticercosis cysts were found adherent to a pulseless right internal carotid artery. This is the first antemortem documentation of a large artery occlusion directly related to Cysticercosis racemosus.

Neurologic complications following chiropractic manipulation: a survey of California neurologists.

To obtain an estimate of how often practicing neurologists in California encounter unexpected strokes, myelopathies, or radiculopathies following chiropractic manipulation, we surveyed each member of the American Academy of Neurology in California and inquired about the number of patients evaluated over the preceding 2 years who suffered a neurologic complication within 24 hours of chiropractic manipulation. Four hundred eighty-six neurologists were surveyed, 177 responded; 55 strokes, 16 myelopathies, and 30 radiculopathies were reported. Patients were between the ages of 21 and 60, and the majority experienced complications following cervical manipulation. Most of the patients continued to have persistent neurologic deficits 3 months after the onset, and about one-half had marked or severe deficits. Nearly all of the strokes involved the posterior circulation and almost one-half were angiographically proven. Patients, physicians, and chiropractors should be aware of the risk of neurologic complications associated with chiropractic manipulation.

Cysticercosis--review of 230 patients.

Two hundred thirty patients with cysticercosis were reviewed. Investigation with CT scan has led to a more detailed understanding of the natural history of human infestation which is essential to the evaluation of new pharmacological and neurosurgical treatments. In contrast to reports emphasizing the need to extirpate all intraventricular cysts, many of our patients needed only ventricular shunt implantation. The ability to evaluate and reevaluate hydrocephalus by CT scan permitted comfortable use of ventricular shunt insertion as the only treatment. Nevertheless, cysts in the fourth ventricle should nearly always be extirpated, because these cysts, by their mass effect, may cause herniation even after shunt implantation. Serious morbidity and death occur chiefly in patients who develop hydrocephalus from intraventricular and basilar infestation. It is unlikely that praziquantel will be effective in patients who present with symptoms of hydrocephalus.

Recurrent ischemic events in two patients with painless vertebral artery dissection.

BACKGROUND AND PURPOSE: Vertebral artery dissection causes endothelial changes and stenosis that may lead to recurrent ischemic neurological events. The diagnosis may not be obvious because the dissection may be painless and "spontaneous" (no obvious trauma). Magnetic resonance angiography has increasingly been used to screen patients for this disorder, but its accuracy has not yet been established. CASE DESCRIPTION: Two patients were admitted with repeated transient ischemic attacks and strokes over 11 months and 1 month, respectively. Neither had a history of trauma, cervical pain, or headache. Magnetic resonance angiography failed to visualize vertebral artery dissections that were later revealed by conventional angiography. One patient's events were stopped by balloon occlusion of the vertebral artery proximal to the posterior inferior cerebellar artery branch. CONCLUSIONS: Magnetic resonance angiography is not yet sensitive enough to always visualize vertebral artery dissection. Vertebral artery dissection is a life-threatening condition that requires aggressive evaluation and treatment.