Retinal ganglion cells that project to the superior colliculus and pretectum in the macaque monkey

Horseradish peroxidase was injected into the superior colliculus or pretectum or both in order to label, by retrograde axoplasmic transport, the retinal ganglion whose cells axons innervate the dorsal midbrain. The dendrites of ganglion cells were sufficiently well-labelled to reveal their overall morphological characteristics. It was therefore possible to compare the number and form of ganglion cells projecting to the midbrain with the total population of ganglion cells as revealed by optic nerve injections, and with ganglion cells labelled by injections in the lateral geniculate nucleus. We found that not more than 10% of all retinal ganglion cells project to the superior colliculus in the macaque monkey. This percentage varies little over the retina, being about 6% of all ganglion cells near the fovea and increasing slightly with eccentricity. The superior colliculus does not receive a projection from P beta cells and only a few P alpha cells terminate there. The majority of cells which project to the superior colliculus have a small- to medium-sized cell body and sparsely branched dendritic tree. We have called them P gamma and P epsilon cells by analogy with the gamma cells and epsilon cells in the cat's retina. Anatomically the P gamma and P epsilon cells are heterogeneous, which would be consistent with the physiological heterogeneity found for ganglion cells which project to the midbrain in monkeys.     

Rectal syphilis mimicking histiocytic lymphoma

Homosexuality is being recognized with increasing frequency in the United States, and the physician must be knowledgeable of the presentations of venereal infection in this population. A 23-year-old man who denied homosexuality presented with a rectal mass and diffuse adenopathy. Biopsy of the mass was interpreted as histiocytic lymphoma. Subsequent serology had positive results for syphilis. Further questioning revealed a history of anorectal intercourse, and special stains of the mass revealed spirochetes. Syphilis must be considered in any young patient presenting with a rectal mass, regardless of the biopsy histologic characteristics or sexual history.     

Chemical and biological characterization of volatile components of environmental samples after fractionation by vacuum line cryogenic distillation

Volatile components from diesel exhaust particles and coal gasifier process gas condensate were vacuum fractionated by cryogenic distillation and identified by infrared spectroscopy and gas chromatography/mass spectrometry. The vacuum distillation line consisted of a sample flask and nine traps cooled from 0°C to ?196°C in approximately 20°C steps. The pressure in the vacuum line of about 10^?2 Torr was maintained with a vacuum pump. Separated compounds were identified by comparison to reference infrared spectra and confirmed by comparison with standards when practical. Volatile compounds identified from the diesel exhaust particle sample included NO_x, carbon dioxide, sulfur dioxide, alkanes, aldehydes, and one and two ring aromatic hydrocarbons. Volatile compounds identified in process gas condensate from a coal gasifier were ammonia, carbonyl sulfide, carbon dioxide, C₃-C₇ hydrocarbons, one and two ring aromatic hydrocarbons, and phenols. Volatile components collected at either 0° or ?24°C were evaluated to determine their genotoxicity using the Chinese hamster ovary/hypoxanthine-guanine phosphoribosyltransferase (CHO/HGPRT) assay. Neither the gasifier condensate nor diesel particle samples produced mutations at the HGPRT locus. The diesel samples were not cytotoxic at the concentrations tested (100 μg/ml) but the gasifier samples resulted in 50% cell killing at concentrations between 25 and 100 μg/ml depending on the temperature of collection and the test conditions. Vacuum desorption with cryogenic distillation has provided a means to separate the volatile components in complex environmental samples to allow chemical and biological characterization of these components.     

Interpretation of single progesterone measurement in diagnosis of anovulation and defective luteal phase: observations on analysis of the normal range

Single serum progesterone determinations were made in 79 apparently normal women with a regular menstrual cycle. A normal range (40 subjects) was derived from the concentrations in the follicular phase and used to define an "anovular" range for luteal phase values (nine out of 39 subjects). The remaining luteal phase values were used to construct an "ovular" range for the luteal phase and, within this range, to define a group of values (less than the 20th centile) which could be described as a "defective luteal phase." The cut off limits between ovular and anovular and between normal and defective luteal phases were respectively two and four times the follicular phase median. It is proposed that the numerical findings of this study may be used as a rule of thumb for defining normality and abnormality from a single serum progesterone determination.     

The Lapidus Arthrodesis: Examining the Effect of the Metatarsal Base Transfixion Screw

The modified Lapidus bunionectomy is a useful and highly powerful procedure for correcting hallux abducto valgus. Traditionally reserved for “severe” deformities, this procedure has seen a recent resurgence in the podiatric community for its unique ability to achieve tri-planar correction of this challenging deformity. Although this procedure has been extensively studied in both biomechanical labs and the clinical arenas, no clear consensus has been achieved regarding optimal fixation for this thought-provoking procedure. The current study examined the differences in strength between commercially available 5-hole locking plates with interfragmentary compression vs a crossed-screw with a third “transfixation” screw construct in a controlled setting. Ten fresh-frozen cadaveric match pair limbs (20 total limbs) were used to complete this study. Ten limbs were randomly assigned to a 3-screw construct. The other 10 contralateral limbs were assigned to a commercially available 5-hole locking plate (5 stainless steel and 5 titanium alloy) with an interfragmentary lag screw construct. The first rays were then isolated and potted into a 4-point bending device. The specimens were loaded to failure in a servohydraulic load frame at a controlled rate. Failure was defined as catastrophic or 3 mm of plantar gapping at the arthrodesis site. The mean maximal load to failure was 310.9 ± 109.4 N for the 3-screw construct. The mean maximal load to failure for the locking plate constructs was 264.1 ± 100.9 N. This difference was not statistically significant (p = .328). These results suggest that a 3-screw construct for Lapidus arthrodesis is as strong as commercially available locking plate constructs.     

Porndemic? A Longitudinal Study of Pornography Use Before and During the COVID-19 Pandemic in a Nationally Representative Sample of Americans

Of the many changes in daily life brought about by the COVID-19 pandemic, social distancing efforts and governmentally mandated lockdowns were among the most drastic. Coinciding with these changes, popular pornography websites made some previously premium content available for free, spurring dramatic increases in traffic to these websites. This increase in time spent at home and reported increases in traffic to specific pornographic websites led to some speculation that pornography use might generally increase over the course of the pandemic and that problematic use might also increase. To test these speculations and quantify the effects of the pandemic and its associated restrictions on social behaviors on pornography use, we analyzed data from a longitudinal sample of American adults. Baseline, nationally representative data were collected in August 2019 via YouGov (N?=?2518). Subsequent data were collected in February 2020 (n?=?1677), May 2020 (n?=?1533), August 2020 (n?=?1470), and October 2020 (n?=?1269). Results indicated that, in May 2020, immediately following the height of the first wave of pandemic-related lockdowns, more people reported past-month pornography use than at other follow-up time points, but less did so than at baseline. Among those who reported use in May 2020, only 14% reported increases in use since the start of the pandemic, and their use returned to levels similar to all other users by August 2020. In general, pornography use trended downward over the pandemic, for both men and women. Problematic pornography use trended downward for men and remained low and unchanged in women. Collectively, these results suggest that many fears about pornography use during pandemic-related lockdowns were largely not supported by available data.