Iatrogenically induced cortical blindness associated with leptomeningeal enhancement

Leptomeningeal enhancement is usually infective or neoplastic in origin. We present a case in which a patient received total parenteral nutrition via a catheter unknowingly placed within the right vertebral artery. We postulate that the hyperosmolar nature of the infused solution induced temporary osmotic disruption of the blood-brain barrier, resulting in cortical blindness associated with localized leptomeningeal enhancement.     

Determinants of glutamine dependence and utilization by normal and tumor-derived breast cell lines

A continual supply of the amino acid glutamine (GLN) may be necessary for cancerous cell growth. GLN plays a central role in multiple metabolic pathways and has long been considered an essential component of tissue culture media. However, the GLN requirements of tumor cell lines and the factors that determine a cell's need for GLN have not been comprehensively studied. Also, it remains unclear how various metabolic pathways contribute to GLN consumption. In the present study, possible determinants of GLN metabolism were examined in seven breast cell lines, two derived from immortalized normal tissue and five of tumor origin. These cells exhibited different dependencies on media GLN concentration for growth and a wide range of GLN utilization rates. GLN uptake was facilitated by a single, common transporter functionally defined as System ASC. However, the affinities for GLN exhibited by this transporter differed appreciably between cell lines. Furthermore, the concentration at which media GLN became a limiting factor for cellular proliferation correlated with transporter affinity. The origin of the cell lines was not a determinant of GLN metabolism because immortalized cells of nontumor origin exhibited GLN dependence and utilization rates comparable to those of tumor-derived cells. The rates of CO2 production from GLN were similar for each cell lines. Rates of GLN disappearance and glutamate appearance in media were strongly correlated, with 32-80% of media GLN converted to glutamate. Both rates were directly affected by media cystine concentration, suggesting that a large portion of glutamate efflux was coupled with cystine import through the amino acid transport system x(c)-. These results demonstrated that cell growth is a function of GLN influx and suggest that GLN is used to supply glutamate and cystine, perhaps for glutathione synthesis.     

Effect of certain drugs in perfused human placenta XII: autacoid antagonism by phenothiazines

The effects of chlorpromazine, prochlorperazine, and trifluoperazine on the pressor actions of serotonin, angiotensin, and bradykinin in the perfused vessels of full-term human placentas were investigated. A significant inhibition of the effect of serotonin was observed with trifluoperazine and chlorpromazine but not with prochlorperazine. The inhibition is attributed to the ability of phenothiazines to cause adrenergic blockade. Because both bradykinin and angiotensin could not be consistently antagonized, it is concluded that they must act primarily via musculotropic mechanisms and only secondarily by stimulation of adrenergic receptors.     

Diagnosis and pathophysiology of paradoxical embolism

A review of the experience with 134 consecutive patients with germinal cell testicular neoplasia indicates that definitively accurate staging of the malignancy at presentation is the single most important prognostic factor. Nearly two-thirds of the patients with all types of germinal malignancies survived or died of other causes and the highest survival rates were seen among patients with earlier stages of seminoma. In recent years patients with all types of germinal malignancies of the testis have been treated by radical retroperitoneal lymphadenectomy with enhancement of survivals. Patients with seminoma and non-seminomatous tumors exhibited increased survival rates with node dissection. In 66 consecutive lymphadenectomies the complication rate was less than 14 per cent, with only 1 death related to the operation. Retroperitoneal lymphadenectomy not only affords therapeutic advantage but also provides an opportunity for accurate surgical staging of disease and allows for rational decision relative to additional treatment, radiation therapy or chemotherapy.     

HIV protease inhibitory bis-benzamide cyclic ureas: a quantitative structure-activity relationship analysis

A series of N,N'-disubstituted cyclic urea 3-benzamides has been synthesized and evaluated for HIV protease inhibition and antiviral activity. Some of these benzamides have been shown to be potent inhibitors of HIV protease with Ki < 0.050 nM and IC90 < 20 nM for viral replication and, as such, may be useful in the treatment of AIDS. The synthesis and quantitative structure-activity relationship for this benzamide series will be discussed.     

Doctors who perform operations. A study on in-hospital surgery in four diverse geographic areas (second of two parts)

To facilitate manpower planning in the surgical field, a study was c onducted into the work loads of surgeons in various specialities in 4 different geographical areas. Surgeons in group practice and surgeons who were Board-certified specialists carried a statistically significant larger work load of surgery. The certified surgeons performed more and more complex operations. The mean operative work load increased steeply with age, reaching a maximum at 40-44 years, and fell linearly after that age. Approximately 18 years following medical school graduation were needed for a surgeon to achieve his maximum work load. The geographic factor had no appreciable effect on work loads. Tables which broke down frequencies for each major type of operation for each type of surgical specialist indicated that even commonplace operations were not frequent events on the average for any individual surgeon. It is concluded from the study that work loads are relatively low due to excessive supply of surgeons. This is of concern because there is some doubt about maintenance of surgical skills by those doctors who perform infrequent operations. The widest variation in practice was evident between ophthalmologists and thoracic surgeons, indicating that manpower planning in this field would have to be done on a specialty-by-specialty basis. 3 plans for redistributing the operative work load and reducing the number of specialist surgeons are considered.