The recruitment of pathology residents: a 1987 conference report on challenges and responses

There is general agreement within pathology that there is a serious problem in the recruitment of US medical graduates into the field. Basic to this decline is inadequate exposure of medical students to the pathologist as a physician who is important to the care of patients and open to a range of clinical and research opportunities unparalleled in other medical specialties. Programs designed to increase the familiarity of students with pathology, both within the curriculum and outside of it, beginning before medical school and extending after medical school, have been proposed to reverse the downtrend in recruitment. Changes in the basic structure of pathology training programs, which would shorten the time commitment, are also considered important in increasing the attractiveness of a pathology career.

Thoracic vertebral fracture as a complication of cardiopulmonary resuscitation

We report the case of a 76-year-old woman who suffered cardiopulmonary arrest three days after being hospitalized with an acute myocardial infarction. She underwent standard cardiopulmonary resuscitative measures for approximately 25 min before being pronounced dead. Autopsy examination revealed a recent myocardial infarction, as well as an acutely fractured tenth thoracic vertebra. Thoracic vertebral fractures are a previously unrecognized complication of cardiopulmonary resuscitation.

Detection of inositol 1,4,5-trisphosphate kinase in retina. A direct demonstration of phosphorylation of inositol 1,4,5-trisphosphate by ATP

The metabolism of myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] consists of two pathways: dephosphorylation by 5-phosphomonoesterase(s) produces inositol 1,4-bisphosphate, and phosphorylation by Ins(1,4,5)P3 3-kinase yields inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4]. The requirements for Ins(1,4,5)P3 kinase activity in retina were characterized. Apparent Km values for ATP and Ins(1,4,5)P3 are 1.4 mM and 1.3 microM respectively. A direct demonstration of phosphorylation of Ins(1,4,5)P3 by [gamma-32P]ATP was achieved. Characterization of the 32P-labelled product revealed that it had the expected chromatographic and electrophoretic properties of Ins(1,3,4,5)P4.

Synergism between environmental lighting and taurine depletion in causing photoreceptor cell degeneration

Experiments were conducted to examine the possible interaction between retinal taurine depletion and environmental lighting in causing photoreceptor cell degeneration. Albino rats were raised from birth in either dim (2 lx) or relatively bright (300 lx) cyclic light. Beginning at weaning, half the animals from both light environments were taurine-depleted by treating them for 10 weeks with guanidinoethyl sulfonate as a 1% solution in their drinking water. The remaining animals were given ordinary tap-water and served as controls. In the 2 lx light environment, taurine depletion caused a decrease in electroretinogram (ERG) a- and b-wave amplitude of 36 and 46%, respectively; however, no photoreceptor cells were lost in this group. Tap-water controls kept in the 300 lx light environment had a 59- and 43% decrease in ERG a- and b-wave amplitude, respectively, and a 21% reduction in the number of photoreceptor cells. In contrast to the other groups, animals that were taurine-depleted in the 300 lx environment showed a marked retinal degeneration. ERG a- and b-wave amplitude was decreased by 94- and 89% respectively and there was a 62% loss of photoreceptor cells. The greatest cell loss occurred in the central superior region of the retina, in which the outer nuclear layer was typically reduced to one to two rows of nuclei. The results of a two-way analysis of variance applied to the data indicated that the effects of taurine depletion on the retina were greater in the 300 lx as compared with the 2 lx environment in terms of loss of photoreceptor cells and reduction in log ERG a- and b-wave amplitude. These findings demonstrate a synergism between environmental lighting and taurine depletion in causing photoreceptor cell degeneration.

Secretory dynamics of bioactive and immunoreactive prolactin in polycystic ovary syndrome

To further investigate prolactin (PRL) secretion in polycystic ovary syndrome (PCO), the authors evaluated immunoreactive (immuno) and bioactive (bio) PRL levels in the basal state and in response to provocative testing with intravenous dopamine (DA), metoclopramide (MCP), and gonadotropin-releasing hormone (GnRH), before and after disulfiram. Basal measurements of immuno-PRL, bio-PRL, and the ratio of bio/immuno-PRL were similar in PCO and controls. The immuno-PRL decrement after DA was greater than that of bio-PRL in both groups (P less than 0.05). After MCP, immuno-PRL increased more than bio-PRL in PCO (P less than 0.01), and this immuno-PRL increment was greater than that of controls (P less than 0.05). Bio-PRL and immuno-PRL increased after GnRH in PCO, but not controls, and these responses were inhibited by disulfiram. These data confirm PRL hypersecretion in some women with PCO, which is better expressed by immunoreactivity than bioactivity. Given the assay systems and patients studied, bioactivity

Video-based image collection for quantitative histopathology

Obtaining histologic images for computer-based morphometric analysis is associated with a number of standardization problems, which must be solved if reproducible data collection is expected. These problems include tissue processing, sectioning and staining, standardizing and calibrating the video camera and determining the appropriate sampling rate (pixels/micron). Suggested solutions for these problems are presented for a specific image analysis system, but are applicable to other systems with similar capabilities. Biologic variability is not eliminated by computer-assisted analysis, so it is important to minimize data-collection artifacts by parallel processing of experimental and control material, as in other investigative work.

Regional distribution of glutathione peroxidase and Glutathione-S-transferase in adult and premature human retinas

The activities of glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GSH-S-tase) were investigated in adult and premature human retinas. The measurements were done in the vascular and avascular regions of premature retinas at gestational age of 22-33 weeks and in the central, mid-peripheral, and far peripheral regions of mature retinas from the age of 1 month to 73 years. Among the premature infants, those who survived for greater than 24 hours were supplemented with alpha-tocopherol (vitamin E) on a periodic basis. The vascular and avascular regions of premature retinas had higher activities of GSH-Px when compared to the central and far peripheral regions of mature retinas. Infants surviving more than 24 hr had higher activities of GSH-S-tase in the avascular region than infants who survived less than 24 hr. Survival did not affect either enzyme activity in the vascular regions. Mature retinas showed a decrease in GSH-Px specific activity with age, but no age-related changes in GSH-S-tase were observed. These data demonstrate that premature infants are born with relatively high levels of GSH-Px and GSH-S-tase.

Phospholipase C activity and substrate specificity in frog photoreceptors

The photoreceptor, like many other cells, undergoes receptor-mediated breakdown of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. The lack of phosphatidylinositol (PdtIns) breakdown during receptor stimulation suggests the existence of a phospholipase C specific for polyphosphoinositides. Phospholipase C activity in frog rod outer segments was assayed with several substrates. The activity was selective for the polyphosphoinositides, phosphatidylinositol 4-phosphate [PtdIns(4)P] and PtdIns(4,5)P2. PtdIns was hydrolysed at 2% of the rate of hydrolysis of PtdIns(4,5)P2. No activity was detected when phosphatidylcholine, phosphatidylserine, or phosphatidylethanolamine were used as substrates. The enzymatic activity was optimal at neutral pH. These findings suggest, but do not prove, that this activity might contain the light-regulated phospholipase C of the photoreceptor.

Effect of low-dose irradiation upon T cell subsets involved in the response of primed A/J mice to SaI cells

A/Jax (A/J) mice primed to Sarcoma I (SaI) exhibit an augmented response in association with low-dose (0.15 Gy) irradiation. This phenomenon is best demonstrated in tumour neutralization (Winn assay) or cell transfer experiments utilizing mice depleted of thymus-derived (T) cells. It is particularly dependent upon the duration of priming and the growth characteristics of the tumour in the primary host. The importance of these two variables appears to relate to their influence upon the cell types responsible for the host response, and includes both an effector and a suppressor component. Radiation-induced inhibition of the suppressor component appears responsible for low-dose augmentation and results in injury to a T cell of the Lyt-1-2+ phenotype. In Winn assays employing equal numbers of immune spleen cells and SaI cells, the smallest tumours are associated with Lyt-1-positive (Lyt-1+2- and Lyt-1+2+) cells and exposure to 0.15 Gy markedly inhibits their anti-SaI activity. Thus, even though the effect is in the opposite direction, both the effector and suppressor components of the anti-SaI response in A/J mice are exceedingly radiosensitive.

The regional distribution of vitamins E and C in mature and premature human retinas

Vitamin E is used to ameliorate retinopathy of prematurity, but little is known about baseline vitamin E levels in retinas of premature infants or the effect of vitamin E supplementation on these levels. Vitamin E and C levels were measured in mature retinas (1 month to 73 years) and in retinas of premature infants (22 to 33 weeks of gestation). The infants fell into two groups: (1) those who survived less than 12 hr and received no vitamin E, and (2) those who survived greater than 4 days and received vitamin E supplementation. Premature infants are born with 5 to 12 percent the vitamin E levels found in mature retinas. Vitamin E levels in vascular and avascular retina of premature infants increased with gestation. Infants born greater than 27 weeks gestation and surviving at least 4 days with vitamin E supplementation demonstrated markedly elevated vitamin E levels in vascular and avascular retina when compared to supplemented infants less than 27 weeks gestation. Premature infants possessed 35-50% higher levels of retinal vitamin C than those found in mature retinas. These data demonstrate that premature infants are born with relatively low levels of retinal vitamin E, particularly in the avascular region, but contain an abundance of retinal vitamin C. These data further suggest that vitamin E supplementation results in a rapid increase in retinal vitamin E levels, particularly in infants greater than 27 weeks gestational age.

Cause of death. Proper completion of the death certificate

Mortality statistics derived from death certificates are the only continuously collected, population-based, disease-related information available in most parts of the world, including the United States. For this reason, every effort must be made to ensure that the most specific, accurate, and complete information regarding cause of death is registered on death certificates. This article discusses identification of the underlying and immediate causes of death, the mechanism and manner of death, and completion of the medical certification section of the death certificate. Examples are given to illustrate the appropriate sequencing of casual information and the selection of the proper underlying causes of death.

Activity of phthalocyanine photosensitizers against human glioblastoma in vitro

In vitro studies utilizing an established human glioblastoma cell line (U87MG) were undertaken to compare the light absorption spectra and photocytotoxicity characteristics of hematoporphyrin derivative (HpD), metal-free phthalocyanine tetrasulfonate (PcS), and aluminum phthalocyanine tetrasulfonate (AlPcS). The peak absorption wavelengths for the compounds studied were: HpD = 630 nm, PcS = 630 nm, AlPcS = 677 nm. Seven different concentrations of each compound (0 to 20 micrograms/ml) were subjected to five different energy levels (40 to 640 joules/cm2) of broad band light (wavelength = 650 +/- 40 nm). Control experiments employing each drug alone and photoactivation alone were also performed. HpD showed a consistent dose-dependent photoactivated cytotoxicity with an abrupt decrease in cell survival when energies of 160 joules/cm2 or more were administered and a drug concentration dependency that resulted in a progressive decline in cell survival beginning at 1.0 microgram/ml. The metal-free PcS had a 10 times greater absorption of light at 675 nm, but only a very weak cytotoxic effect, which occurred at concentrations in excess of 10.0 micrograms/ml and energy levels greater than 320 joules/cm2. AlPcS, however, displayed a 100-fold increase in light absorption at 675 nm when compared to HpD. This was coupled with a decrease in cell survival similar to the HpD curves, but with a much steeper slope of percentage cell kill at lower drug concentrations and energy dosages. The control studies did not result in any appreciable cytotoxic effect. The data suggest that AlPcS holds promise as a second generation photosensitizer in the photodynamic treatment of human gliomas.

Effect of dihydropyridines and diphenylalkylamines on pentylenetetrazol-induced seizures and cerebral blood flow in cats

Nimodipine, a dihydropyridine that interacts with a Ca++ channel-associated binding site, when delivered (30 to 150 micrograms/kg) intra-arterially (ia) to enflurane-anesthetized cats, produced a dose-dependent suppression of seizures evoked by pentylenetetrazol. A comparable suppression was produced by clonazepam (1 to 30 micrograms/kg, ia). Phenytoin was maximally effective only at nearly lethal doses (90 mg/kg, ia). Verapamil, a diphenylalkylamine that interacts with a separate Ca++ channel-associated site, at the maximum nonlethal dose (6 mg/kg, ia) resulted in a mild facilitation of seizure activity. The drug vehicle used in these studies (50% polyethylene glycol-400) had no effect when given alone. Regional cerebral blood flow (rCBF) as measured by the clearance of xenon-133 was markedly elevated immediately after the onset of seizure activity (89 +/- 3 to 168 +/- 4 ml/100 gm/min). Concurrent with their resolution of the seizure activity, both nimodipine and clonazepam reduced rCBF to near preseizure levels and preserved the rCBF response to hypercarbia which would otherwise have been abolished following prolonged seizure activity. Moreover, the effect of nimodipine on rCBF and seizures occurred without any prominent alterations in mean arterial blood pressure as compared to preseizure levels. These data support the proposition that a dihydropyridine Ca++ channel binding site may play a role in modulating paroxysmal neuronal activity, and suggest that this class of agents may reflect a novel group of antiepileptic drugs.

Male-to-female transmission of human immunodeficiency virus

Ninety-seven female sexual partners of 93 men infected with human immunodeficiency virus were studied. All of the women had sexual contact within the year before their partner had been diagnosed as having acquired immunodeficiency syndrome or was found to have a positive reaction on the human immunodeficiency virus serologic test. Fifty-seven percent were the partners of bisexual men. Overall, 23% of the women were infected (95% confidence interval, 15% to 32%). The total number of exposures to the index case (sexual contacts with ejaculation) and the specific practice of anal intercourse, also with the infected partner, were associated with transmission. Neither condom use, total number of sexual partners since 1978, nor lifetime number of sexually transmitted diseases was associated with infection.

Cause of death. Proper completion of the death certificate

Mortality statistics derived from death certificates are the only continuously collected, population-based, disease-related information available in most parts of the world, including the United States. For this reason, every effort must be made to ensure that the most specific, accurate, and complete information regarding cause of death is registered on death certificates. This article discusses identification of the underlying and immediate causes of death, the mechanism and manner of death, and completion of the medical certification section of the death certificate. Examples are given to illustrate the appropriate sequencing of causal information and the selection of the proper underlying cause of death.

Factors influencing discrepancies between premortem and postmortem diagnoses

A study of 2067 autopsies collected from 32 university and community hospitals of various sizes located throughout the United States showed the rate of discrepancies between premortem and postmortem diagnoses to be influenced by the type and size of hospital, the age and sex of the patient, and the disease responsible for the patient's death. Of equivocal or no influence were the length of the terminal hospitalization, the degree of clinical involvement in the case of the person responsible for establishing the discrepancy level, and the autopsy rate, at least as it applies to community hospitals.

Suppression of pentylenetetrazole seizures by oral administration of a dihydropyridine Ca2+ antagonist

We previously demonstrated that the dihydropyridine calcium channel blocker, nimodipine, is an effective anticonvulsant in experimental seizures when administered parentally. Reported now are the results for the oral administration of nimodipine in pentylenetetrazole (PTZ)-induced seizures in the rabbit. Twenty rabbits were randomly assigned into 10 controls and 10 treated with nimodipine 5 mg/kg/day orally for 5 days. All animals received increasing doses of the convulsant PTZ intravenously (i.v). The epileptogenecity of this agent was assessed in all animals (mg/kg) by four electrocorticographic criteria: first seizure greater than 5 s, two seizures within 5 min, epileptiform activity for 1 h, and status epilepticus. In all four categories, nimodipine increased the seizure threshold by 50-60%. The dose of PTZ required to produce the first seizure was 27.0 +/- 5.4 mg/kg in controls and 49.6 +/- 9.9 mg/kg in treated animals (p less than 0.001). Similar values were obtained for the other three electrocorticographic categories. There were no observable adverse side effects. The results confirm our previous findings that calcium influx is critical for seizure induction, and that selective central nervous system (CNS) calcium channel blockers may emerge as a new class of anticonvulsants.

In vivo studies on intracellular pH, focal flow, and vessel diameter in the cat cerebral cortex: effects of altered CO2 and electrical stimulation

The time course of changes in cortical tissue pH (pHi) and blood flow during cortical seizures in halothane-anesthetized cats was examined. The clearance of the molecular form of umbelliferone (Um) was used to estimate focal cortical blood flow (CBFu), whereas the ratio of the molecular to the ionic form of the molecule was used to concurrently calculate the local pHi. Resting pHi and flow in normocarbic animals was 7.116 +/- 0.008 and 46 +/- 8 ml/100 g/min, respectively. Respiratory induced alterations of PaCO2 over a range of 20-60 torr revealed a correlated change in pHi from 7.39 +/- 0.05 to 7.01 +/- 0.03 and a monotonic increase in the rate of Um clearance (slope 0.89 +/- 0.13 ml/100 g/min/torr). Focal electrical stimulation of the cortex resulted in a rapid vasodilation (50% dilation = 1-3 s) of pial arterioles and venules and an increase in Um clearance. pHi showed no significant change until around 10 s. The maximum fall in pHi occurred by 30-60 s (6.85 +/- 0.054). Longer intervals of stimulation (10 min) resulted in no further decline in pHi, but upon cessation of stimulation. pHi remained acidotic for poststimulation periods up to 10 min, with a mild but statistically significant acidosis being observed at 20 min. The absolute decline in pH observed following stimulation appeared to be closely regulated, as comparable levels following stimulation were observed during hypocarbia and hypercarbia. These observations thus suggest that pHi regulation during intense cortical activation may be considered in three phases: following the onset of activity, an initial acute regulation of pHi at control levels; an intracellular acidosis of around 6.8, which is closely regulated and which can be readily reversed upon termination of stimulation; and during continued stimulation, a change in state where in spite of no further change in pHi, the ability of the cortex to return to control pHi appears to be significantly impaired.

Effect of light history on rod outer-segment membrane composition in the rat

Albino rats were born and raised through 12 weeks of age in 12L:12D regimes of 5, 300- or 800-lx illuminance. Upon killing, the animals' retinas were examined for the following: (1) rhodopsin of whole retina and isolated rod outer-segment membrane; (2) retinal morphology, including outer segment length and outer nuclear layer area; and (3) outer-segment membrane lipid biochemistry. The three groups of animals show significant differences with respect to one another for nearly every parameter measured. Rod outer-segment membranes of rats raised in dim cyclic light (5 lx) have high rhodopsin packing densities, high levels of polyunsaturated fatty acids, and low cholesterol levels in comparison with animals raised in brighter illuminances (300- or 800 lx). The mole ratio of phospholipid to rhodopsin in the outer-segment membrane of rats raised in 5-lx cyclic light is only 43% of that of rats raised in 800-lx cyclic light. The difference between these two groups of animals for docosahexaenoic acid is greater than three times, with dim light-reared animals showing higher levels. These rats (5 lx-reared) have less cholesterol in their photoreceptor outer segments, 6.6 mol% compared with 19.7 mol% for animals from the 800-lx regime. In all cases, rats from the intermediate rearing illuminance (300 lx) exhibit intermediate membrane composition values. It is likely that these differences in membrane composition illustrate a profound effect of light history on photoreceptor function.

The San Francisco Men's Health Study: III. Reduction in human immunodeficiency virus transmission among homosexual/bisexual men, 1982-86

The prevalence and incidence of infection by the human immunodeficiency virus (HIV) has been under study in a cohort of 1,034 single men recruited by area probability sampling from a six kilometer square area of San Francisco where the epidemic of acquired immunodeficiency syndrome (AIDS) has been most severe. Prevalence of infection among homosexual/bisexual study subjects increased from an estimated 22.8 per cent during the last half of 1982 to 48.6 per cent during the period July through December 1984. During three subsequent six-month periods, prevalence remained stable at approximately 50 per cent. Annual infection rates, measured by seroconversion among seronegative study subjects, decreased from an estimated 18.4 per cent per year from 1982 to 1984, to 5.4 and 3.1 per cent during the first and second halves of 1985, and to 4.2 per cent during the first six months of 1986. These declines were associated with reductions of 60 per cent or more in the prevalence of high-risk sexual practices associated with both acquiring and disseminating infection by the human immunodeficiency virus.

Effect of light history on retinal antioxidants and light damage susceptibility in the rat

Albino rats were born and raised to 12 weeks of age in 12L:12D light regimes of 5, 300 or 800 lx. Upon killing, the activities of the following glutathione enzymes were measured in the neuroretina: (1) glutathione peroxidase; (2) glutathione-S-transferase; and (3) glutathione reductase. Also measured were vitamin E, ascorbic acid, and the levels of oxidized and reduced glutathione. Animals raised in 800-lx cyclic light have a significant increase in the retinal activities of the three glutathione enzymes over activities measured in animals raised in the two dimmer regimes. The retinal level of vitamin E, measured per nmol of lipid phosphorus, is directly and significantly correlated with rearing illuminance (P less than 0.05). The same is true of retinal ascorbic acid, which shows a 30% increase in the 800-lx-reared rats over the level of those raised in the intermediate light regime (300 lx). Some of the animals from each group were exposed to 2000 lx for 24 hr to determine if correlations existed between the levels of retinal antioxidants listed above and susceptibility to light damage. Animals raised in 5-lx cyclic light lost almost all of their photoreceptors as a result of the exposure. Rats raised in 300-lx cyclic light lost a small but significant number (ca. 20%), while those raised in 800 lx sustained no light damage. Electroretinographic evaluation supports these morphometrical findings.