A comprehensive literature scoping review of infection prevention and control methods for viral-mediated gene therapies

Objective

This comprehensive literature scoping review outlines available infection prevention and control (IPC) methods for viral-mediated gene therapies and provides one IPC strategy for the healthcare setting based on a single-center recommendation.

Methods

A team of experts in pharmacy, healthcare epidemiology, and biosafety with experience in viral-mediated gene therapy was assembled within a pediatric hospital to conduct a comprehensive literature scoping review. The comprehensive review included abstracts and full-text articles published since 2009 and utilized prespecified search terms of the five viral vectors of interest: adenovirus (AV), retrovirus (RV), adeno-associated virus (AAV), lentivirus (LV), and herpes simplex virus (HSV). Case reports, randomized controlled trials, and bench research studies were all included, while systematic reviews were excluded.

Results

A total of 4473 case reports, randomized control trials, and benchtop research studies were identified using the defined search criteria. Chlorine compounds were found to inactivate AAV and AV, while alcohol-based disinfectants were ineffective. There was a relative paucity of studies investigating surface-based disinfection for HSV, however, alcohol-based disinfectants were effective in one study. Ultraviolent irradiation was also found to inactivate HSV in numerous studies. No studies investigated disinfection for LV and RV vectors.

Conclusions

The need to define IPC methods is high due to the rapid emergence of viral-mediated gene therapies to treat rare diseases, but published clinical guidance remains scarce. In the absence of these data, our center recommends a 1:10 sodium hypochlorite solution in clinical and academic environments to ensure complete germicidal activity of viral-mediated gene therapies.

The Nutritarian Women’s Health Study (NWHS): Cohort 1

Plant-based dietary patterns are associated with chronic disease risk reduction, prevention, and reversal. As such, the Nutritarian diet is a dietary plan grounded in the daily consumption of micronutrient-dense, plant-rich foods that satisfy nutrient needs with a corresponding improvement in overall health. The Nutritarian Women’s Health Study was a fully-online intervention that included supportive, automated email messages, with participants self-reporting dietary adherence and anthropometric measurements quarterly. Changes in Body Mass Index (BMI) were not significant. The groups with the lowest baseline Waist-to-Height-Ratio (WHtR) showed an initial increase followed by a decrease. Responses related to dietary adherence showed that most participants easily consumed greens, beans, onions/garlic, berries, and seeds, avoided animal products, alcohol, and refined foods, but had difficulty with regularly consuming mushrooms and tomatoes. A midpoint questionnaire revealed participants consumed an overwhelming amount of their meals/snacks according to the dietary plan and about half found it easy/very easy to eat strictly Nutritarian. A large majority reported a positive change in health from participating in the study. The barriers to following the dietary plan include a busy lifestyle and the opposing views/pressures from friends, family, co-workers, and/or spouse/partner. It is important to evaluate this fully-online approach when considering future interventions.

Safety and Efficacy of Prophylactic Levofloxacin in Pediatric and Adult Hematopoietic Stem Cell Transplantation Patients

Levofloxacin has been widely used for bacteremia prophylaxis in the pre-engraftment setting for patients undergoing hematopoietic stem cell transplantation (HSCT), but data supporting this practice are inconsistent. In addition to concern for lack of benefit, there are also concerns that this practice could increase the rates of Clostridium difficile (C diff) infections, the incidence of multidrug-resistant organisms (MDRO) or lead to increased incidence of acute graft-versus-host disease (aGVHD) by disrupting the gut microbiome. This study aimed to assess the safety and efficacy of levofloxacin as bacterial prophylaxis in pediatric and young adult patients undergoing allogeneic or autologous HSCT at a single pediatric center. We conducted a retrospective chart review evaluating patients age ≥6 months who underwent HSCT at our center between January 1, 2016, and July 31, 2020. Patients who underwent transplantation before March 2018 did not receive levofloxacin prophylaxis, whereas those who underwent transplantation after April 2018 did receive levofloxacin prophylaxis. Each transplantation was included as a separate episode if the patient underwent more than 1 transplantation during the inclusion time. The primary outcome of this study was the proportion of patients who experienced at least 1 bacterial bloodstream infection (BSI) in the first 100 days post-transplantation. Secondary outcomes included the number of non-levofloxacin antibiotic days post-transplantation, the incidence of aGVHD, the occurrence of C diff infections, and development of MDRO. A total of 370 HSCT recipients with a median age of 6.7 years (range, 0.5 to 39 years) were included in this study. Seventy-two patients had undergone more than 1 transplantation, and thus we had 443 transplantations to observe. Of these, 216 did not include levofloxacin prophylaxis and 227 included levofloxacin prophylaxis. There were no differences in baseline characteristics between the 2 groups except for age; patients in the non-levofloxacin prophylaxis group were younger (8.1 years vs 9.6 years; P = .05). There were no between-group differences in rates of death at 100 days, antibiotic use, fungal infections, or MDRO infections. Patients in the non-prophylaxis group developed more bacterial BSI in the first 100 days post-HSCT (27% versus 17%; P = .004) and more C diff infections (20% versus 9%; P = .003) than patients who received levofloxacin prophylaxis. In addition, more acute GVHD was seen in the patients without levofloxacin prophylaxis (P = .014). Levofloxacin prophylaxis given from day -2 of HSCT through engraftment was significantly associated with decreased bacterial BSI in the first 100 days post-transplantation and was not associated with increased risks of C diff, acute GVHD, or MDRO. Our study supports the use of levofloxacin prophylaxis in the peritransplantation period. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Protocol and Preliminary Results of the Nutritarian Women's Health Study: A Longitudinal Effectiveness-Implementation Hybrid Study Assessing Dietary Intake and Health Outcomes

Whole-food plant-rich dietary patterns have been shown to be associated with significant health benefits and disease-risk reduction. One such program, which has been gaining popularity, is the micronutrient-dense plant-rich (mNDPR) "Nutritarian" diet. The goal of this study is to determine the feasibility of implementing an online mNDPR "Nutritarian" intervention program and to determine the effectiveness of this program in reducing risk of chronic disease in women. The Nutritarian Women's Health Study is a long-term online longitudinal hybrid effectiveness-implementation study. Participants are recruited through social media, medical professionals/offices, and nutrition-related events and conferences. Participants receive online nutrition education and complete regular self-reported questionnaires regarding lifestyle, nutrition practices, and health. The online intervention program appears to be feasible and effective. Some decline in dietary adherence, particularly for certain food types, was observed during the study. For groups at risk, based on body mass index or waist-to-height ratio, there were initial decreases in body mass index and waist-to-height that leveled off over time, in some cases returning to baseline measures. The study suggests the implementation of the Nutritarian dietary pattern, through an online intervention component, may be effective in reducing the risk of chronic disease, with implications for clinical and public health practice.

Objective detection and localization of multiple sclerosis lesions on magnetic resonance brainstem images: validation with auditory evoked potentials

To develop an objective method for detecting multiple sclerosis (MS) brainstem lesions, magnetic resonance (MR) images (multiple planar, spin-echo, acquired in three planes of section) of sixteen MS patients and fourteen normal subjects were analyzed with an algorithm that detected regions with a relatively increased intensity on both a spin-echo image and a T2 image. To be considered a lesion, such regions had to overlap in at least two orthogonal planes. Using a digitized atlas of the human brainstem, the lesion locations were mapped with respect to the brainstem anatomy. This method was evaluated by comparing the location of MS lesions with the brainstem auditory evoked potentials obtained from these subjects. Brainstem lesions were detected in five MS patients; four had lesions impinging upon the auditory system and one did not. All four had abnormal evoked potentials. The fourteen normal subjects, the one MS patient with brainstem lesions outside the auditory pathway, and the eleven other MS patients with no brainstem lesions all had normal evoked potentials. The requirement that lesions be detected in at least two planes of section greatly improved the specificity of the algorithm. The consistency between the MR and brainstem auditory evoked potentials results supports the validity of this imaging analysis algorithm for objectively localizing brainstem lesions.

Bone dysplasia sclerosteosis results from loss of the SOST gene product, a novel cystine knot-containing protein

Sclerosteosis is an autosomal recessive sclerosing bone dysplasia characterized by progressive skeletal overgrowth. The majority of affected individuals have been reported in the Afrikaner population of South Africa, where a high incidence of the disorder occurs as a result of a founder effect. Homozygosity mapping in Afrikaner families along with analysis of historical recombinants localized sclerosteosis to an interval of approximately 2 cM between the loci D17S1787 and D17S930 on chromosome 17q12-q21. Here we report two independent mutations in a novel gene, termed "SOST." Affected Afrikaners carry a nonsense mutation near the amino terminus of the encoded protein, whereas an unrelated affected person of Senegalese origin carries a splicing mutation within the single intron of the gene. The SOST gene encodes a protein that shares similarity with a class of cystine knot-containing factors including dan, cerberus, gremlin, prdc, and caronte. The specific and progressive effect on bone formation observed in individuals affected with sclerosteosis, along with the data presented in this study, together suggest that the SOST gene encodes an important new regulator of bone homeostasis.

Hand-assisted laparoscopy for the removal of an esophageal leiomyoma

The patient is a 39-year-old male who presented with noncardiac chest pain. His evaluation disclosed an esophageal leiomyoma. In this paper we will demonstrate the pre-operative findings and technique for removal of a benign esophageal tumor using hand-assisted laparoscopy. The patient was discharged home 2 days postoperative and returned to work 2 weeks postoperative with complete resolution of his symptoms. Hand-assisted laparoscopy provides a postoperative course that parallels the recovery from conventional laparoscopy. Additionally, the tactile sense that a surgeon looses from conventional laparoscopy is regained by this technology.

An interactive tutorial-based training technique for vertebral morphometry

The purpose of this work was to develop a computer-based procedure for training technologists in vertebral morphometry. The utility of the resulting interactive, tutorial based training method was evaluated in this study. The training program was composed of four steps: (1) review of an online tutorial, (2) review of analyzed spine images, (3) practice in fiducial point placement and (4) testing. During testing, vertebral heights were measured from digital, lateral spine images containing osteoporotic fractures. Inter-observer measurement precision was compared between research technicians, and between technologists and radiologist. The technologists participating in this study had no prior experience in vertebral morphometry. Following completion of the online training program, good inter-observer measurement precision was seen between technologists, showing mean coefficients of variation of 2.33% for anterior, 2.87% for central and 2.65% for posterior vertebral heights. Comparisons between the technicians and radiologist ranged from 2.19% to 3.18%. Slightly better precision values were seen with height measurements compared with height ratios, and with unfractured compared with fractured vertebral bodies. The findings of this study indicate that self-directed, tutorial-based training for spine image analyses is effective, resulting in good inter-observer measurement precision. The interactive tutorial-based approach provides standardized training methods and assures consistency of instructional technique over time.

Computer-based methods for measuring joint space and estimating erosion volume in the finger and wrist joints of patients with rheumatoid arthritis

OBJECTIVE

This study was conducted 1) to determine the feasibility of using computer programs to measure radiographic joint space width and estimate erosion volume in the hands of patients with rheumatoid arthritis (RA), and 2) to compare the new computer-based methods with established scoring methods.

METHODS

To measure the joint space width in the finger and wrist joints of RA patients, hand and wrist radiographic films were scanned using a tabletop scanner and analyzed with programs written using the "macro" capabilities of NIH Image software. Estimation of erosion volume was determined by utilizing gray-scale intensity to calibrate bone density units per mm3, which made possible comparisons between the erosions and noneroded, anatomically similar sites.

RESULTS

In 3 sets of duplicate measurements of joint space width on 79, 48, and 48 finger and wrist joints, the mean absolute deviation from the mean of the 2 measurements was 0.036 mm (SD 0.034), 0.032 mm (SD 0.049), and 0.021 mm (SD 0.016), respectively. Joint space measurements and scoring of joint space narrowing both demonstrated a difference between active treatment and placebo in an old trial set on gold therapy (P = 0.03 and P = 0.01, respectively). Two repeated measurements of bone density units in the bones of 3 different hands differed from the mean of the measurement by 2.29-4.04%. In 2 experiments, estimates of erosion volume showed a greater difference between gold therapy and placebo than did erosion scores in the trial set (P = 0.049 and P = 0.016 versus P = 0.27).

CONCLUSION

Computer-based methods for measuring finger and wrist joint spaces and estimating erosion volume in patients with RA agree with the results of radiographic scoring of erosions and joint space narrowing.

Correlating MR lesions and functional deficits in multiple sclerosis patients. Anatomical atlas registration

Although brain magnetic resonance (MR) imaging is increasingly being used as an objective outcome measure in treatment trials for multiple sclerosis (MS), findings correlating conventional MR imaging and disabilities in established MS have been inconsistent. In some studies, measures of MR lesion status, such as numbers of lesions or MS lesion load (volume), have shown limited correlations with clinical scores such as the Kurtzke Expanded disability scale (EDSS). Other studies have shown clear correlations between MR findings and measures of disability in MS. Further development of image processing techniques should help elucidate the relationships between MR findings and disease processes in MS.

Cerebral N-acetylaspartate is low in patients with multiple sclerosis and abnormal visual evoked potentials

PURPOSE

Our purpose was to compare cerebral proton MR metabolite changes in patients with multiple sclerosis (MS) and abnormal visual evoked potentials (VEPs) with those in MS patients with normal VEPs.

METHODS

Seventeen subjects with clinically definite MS were studied with VEPs and MR spectroscopic imaging. Proton MR metabolites were measured using a fast spectroscopic imaging technique called proton echo-planar spectroscopic imaging (PEPSI). Kurtzke's Expanded Disability Status Scale (EDSS) score was also ascertained for each subject to obtain a clinical rating. Twelve regions of interest within the visual pathway of the cerebrum were evaluated for levels of N-acetylaspartate (NAA), choline, creatine, and the presence or absence of MR-detectable lesions.

RESULTS

PEPSI NAA values (water-normalized, CSF-corrected) were significantly lower in MS subjects with abnormal VEPs than in subjects with normal VEPs. MR-detectable lesion fractions and EDSS scores were also significantly different between the two VEP groups, but NAA comparison had a P value 100 times less than either of these measures.

CONCLUSION

In patients with MS, NAA measurements in the optic pathways of the brain were sensitive to VEP abnormalities. NAA was more sensitive to VEP changes than were choline, creatine, MR-detectable lesions, and EDSS score.

Familial streptomycin ototoxicity in a South African family: a mitochondrial disorder

The vestibular and ototoxic effects of the aminoglycoside antibiotics (streptomycin, gentamycin, kanamycin, tobramycin, neomycin) are well known; streptomycin, in particular, has been found to cause irreversible, profound, high frequency sensorineural deafness in hypersensitive persons. Aminoglycoside ototoxicity occurs both sporadically and within families and has been associated with a mitochondrial DNA (mtDNA) 1555A to G point mutation in the 12S ribosomal RNA gene. We report on the molecular analysis of a South African family with streptomycin induced sensorineural deafness in which we have found transmission of this same predisposing mutation. It is now possible to identify people who are at risk of hearing loss if treated with aminoglycosides in the future and to counsel them accordingly. In view of the fact that aminoglycoside antibiotics remain in widespread use for the treatment of infections, in particular for tuberculosis, which is currently of epidemic proportions in South Africa, this finding has important implications for the family concerned. In addition, other South African families may potentially be at risk if they carry the same mutation.

Functional MR spectroscopy of the auditory cortex in healthy subjects and patients with sudden hearing loss

PURPOSE

To use MR spectroscopy to study the biochemical changes produced by auditory stimuli in patients with sudden sensorineural hearing loss and to compare these findings with the biochemical changes seen in healthy volunteers.

METHODS

Single-voxel MR spectroscopy was used to study biochemical changes in the auditory cortex in 11 control subjects and 19 patients with sudden sensorineural hearing loss. MR spectroscopic signals were measured during three different sound conditions (scanner noise, music, and sirens).

RESULTS

A lower MR spectroscopic lactate signal was observed in control subjects during the music stimulus than during the other sound conditions. This music-induced lactate change was not observed in patients with hearing loss. The other proton metabolites (choline, creatine, N-acetylaspartate [NAA]) remained stable during the different auditory stimuli. However, the NAA/creatine ratio was higher in the auditory cortex of patients than in the control subjects, and was not dependent on the sound condition.

CONCLUSION

The detection of stimulus-induced and stable biochemical MR spectroscopic changes in patients with hearing loss may be useful in assessing disease activity.

Image magnification in renal and superior mesenteric angiography: CT calculation and assessment of variables

PURPOSE

To estimate the magnification that occurs in conventional renal and mesenteric angiography and to assess the influence of anatomic and technical variables.

PATIENTS AND METHODS

Anticipated image magnification was derived solely from computed tomographic (CT) measurements obtained of 152 consecutive adult patients who underwent abdominal CT. Scans showed the distance from the origin and distal portions of both renal arteries to the anterior and posterior body surfaces, as well as the distance from the origin of the superior mesenteric artery to the lateral body surfaces. Assuming a 101.6-cm (40-inch) source-to-image receptor distance, the degree of magnification was calculated for posteroanterior, anteroposterior, and lateral radiographic imaging techniques.

RESULTS

Calculated mean magnification for the proximal renal artery was 14.5% (range, 7.2%-25.8%) with posteroanterior imaging and 26.7% (range, 22.3%-36.7%) with anteroposterior imaging and a 10-cm-thick table. Mean magnification for the distal renal artery was 16.1% (range, 8.8%-25.3%) with posteroanterior imaging and 24.6% (range, 19.5%-36.4%) with anteroposterior imaging and a 10-cm-thick table. Magnification of the superior mesenteric artery was 17.8% (range, 12.5%-33.9%) with left lateral imaging. Regression analysis documented a linear relationship between percentage magnification and body diameter.

CONCLUSION

Arterial location, imaging technique, and especially body habitus affect the degree of magnification in a predictable fashion.

Craniosynostosis, microcephaly, hydrancephaly, humero-radial synostosis, and thumb aplasia: a new syndrome?

We describe a growth-retarded newborn infant with craniosynostosis, microcephaly, hydrancephaly, oligodactyly, humero-radial synostosis, and normal chromosomes. The combination of anomalies has hitherto been unreported and we consider this to be a "new" syndrome.

Hepatic helical CT: effect of reduction of iodine dose of intravenous contrast material on hepatic contrast enhancement

PURPOSE

To evaluate the effect of a reduction in iodine dose by altering volume and/or concentration of contrast material on hepatic contrast enhancement (HCE) values during hepatic helical computed tomography (CT).

MATERIALS AND METHODS

One hundred eleven patients were randomized into four contrast material protocols according to concentration (in milligrams of iodine per milliliter)/volume (in milliliters)/grams of iodine: group 1, ioversol, 320/150/48; group 2, ioversol, 320/100/32; group 3, iohexol, 300/150/45; group 4, ioversol, 300/100/30. Helical CT protocols were identical for the four groups. Time-attenuation curves were constructed; the mean HCE, contrast enhancement index (CEI), and optimal liver scanning interval (OLSI) were calculated; and the results were compared statistically. RESULTS;: Time-attenuation curves, mean HCE, CEI, and OLSI of groups 1 and 3 were significantly superior to those for groups 2 and 4. Decrease in volume from 150 to 100 mliters decreased mean HCE by 27%, CEI by 69%, and OLSI from 80%-100% to 0%-43% at threshold levels of 40-60 HU.

CONCLUSION

Decrease in iodine dose from 45-48 g to 30-32 g significantly decreases all HCE values, which potentially decreases detection of focal hypovascular hepatic lesions.

Multiple sclerosis lesions of the auditory pons are not silent

To understand the relationship between brainstem lesions and auditory neurology in patients with multiple sclerosis, we compared behavioural, electrophysiological and imaging data in 38 patients with probable or definite multiple sclerosis and normal or near normal hearing. Behavioural measures included (i) general hearing tests (audiogram, speech discrimination) and (ii) hearing tests likely to be critically dependent upon brainstem processing (masking level difference, interaural time and level discrimination). Brainstem auditory evoked potentials provided the electrophysiological data. Multiplanar high-resolution MRI of the brainstem provided the anatomical data. Interaural time discrimination for high-frequency sounds was by far the most sensitive of all tests with abnormalities in 71% of all subjects. Whenever any other test was abnormal this test was always abnormal. Interaural time discrimination for low-frequency sounds and evoked potentials were closely related and next most sensitive with abnormalities in approximately 40% of all subjects. Interaural level discrimination and masking level difference were least sensitive with abnormalities in < 10% of subjects. Speech discrimination scores correlated significantly with the masking level differences, as well as with interaural time discrimination for high-frequency sounds. Pontine lesions were found in five of the 16 patients, in whom an objective method for detecting magnetic resonance lesions could be applied. All four with lesions involving the pontine auditory pathway had marked abnormalities in interaural time discrimination and evoked potentials. None of the other 12 had evoked potentials abnormalities. We conclude that neurological tests requiring precise neural timing can reveal behavioural deficits for multiple sclerosis lesions of the auditory pons that are otherwise 'silent'. Of all neurological systems the auditory system at the level of the pons is probably the most sensitive to multiple sclerosis lesions, because of its exceptional dependence upon neural timing in the microsecond range and the lack of redundancy in the encoding of high-frequency sounds. Precise neural timing may be critical for some aspects of speech processing.

Effects of multiple sclerosis brainstem lesions on sound lateralization and brainstem auditory evoked potentials

Magnetic resonance (MR) imaging, brainstem auditory evoked potentials (BAEPs), and tests of interaural time and level discrimination were performed on sixteen subjects with multiple sclerosis (MS). Objective criteria were used to define MR lesions. Of the eleven subjects in whom no pontine lesions were detected and the one subject who had pontine lesions that did not encroach upon the auditory pathways, all had normal BAEPs and interaural level discrimination, although a few had abnormal interaural time discrimination. Of four subjects with lesions involving the pontine auditory pathway, all had both abnormal BAEPs and abnormal interaural time discrimination; one also had abnormal interaural level discrimination. Analysis of the data suggest the following: waves I and II are generated peripheral to the middle of the ventral acoustic stria (VAS); wave III is generated ipsilaterally in the region of the rostral VAS, caudal superior olivary complex (SOC) and trapezoid body (TB); and waves V and L are generated contralaterally, rostral to the SOC-TB. The region of the ipsilateral rostral SOC-TB is implicated as part of the pathway involved in the generation of waves V and L. Interaural time discrimination of both high and low frequency stimuli were affected by all brainstem lesions that encroached on auditory pathways. A unilateral lesion in the region of the LL affected interaural time discrimination for low-frequency stimuli less severely than bilateral lesions of the LL or a unilateral lesion of the VAS. The only interaural level discrimination abnormality occurred for a subject with a unilateral lesion involving the entire rostral VAS. It appears that detailed analysis of lesion locations coupled with electrophysiological and psychophysical data holds promise for testing hypotheses concerning the function of various human auditory brainstem structures.

Binaural auditory processing in multiple sclerosis subjects

In order to relate human auditory processing to physiological and anatomical experimental animal data, we have examined the interrelationships between behavioral, electrophysiological and anatomical data obtained from human subjects with focal brainstem lesions. Thirty-eight subjects with multiple sclerosis were studied with tests of interaural time and level discrimination (just noticeable differences or jnds), brainstem auditory evoked potentials and magnetic resonance (MR) imaging. Interaural testing used two types of stimuli, high-pass (> 4000 Hz) and low-pass (< 1000 Hz) noise bursts. Abnormal time jnds (Tjnd) were far more common than abnormal level jnds (70% vs 11%); especially for the high-pass (Hp) noise (70% abnormal vs 40% abnormal for low-pass (Lp) noise). The HpTjnd could be abnormal with no other abnormalities; however, whenever the BAEPs, LpTjnd and/or level jnds were abnormal HpTjnd was always abnormal. Abnormal wave III amplitude was associated with abnormalities in both time jnds, but abnormal wave III latency with only abnormal HpTjnds. Abnormal wave V amplitude, when unilateral, was associated with a major HpTjnd abnormality, and, when bilateral, with both HpTjnd and LpTjnd major abnormalities. Sixteen of the subjects had their MR scans obtained with a uniform protocol and could be analyzed with objective criteria. In all four subjects with lesions involving the pontine auditory pathway, the BAEPs and both time jnds were abnormal. Of the twelve subjects with no lesions involving the pontine auditory pathway, all had normal BAEPs and level jnds, ten had normal LpTjnds, but only five had normal HpTjnds. We conclude that interaural time discrimination is closely related to the BAEPs and is dependent upon the stimulus spectrum. Redundant encoding of low-frequency sounds in the discharge patterns of auditory neurons, may explain why the HpTjnd is a better indicator of neural desynchrony than the LpTjnd. Encroachment of MS lesions upon the pontine auditory pathway always is associated with abnormal BAEPs and abnormal interaural time discrimination but may have normal interaural level discrimination. Our data provide one of the most direct demonstrations in humans of relationships among auditory performance, evoked potentials and anatomy. We present a model showing that many of these interrelationships can be readily interpreted using ideas developed from work on animals, even though these relationships could not have been predicted with confidence beforehand. This work provides a clear advance in our understanding of human auditory processing and should serve as a basis for future studies.

Genes for human vitamin K-dependent plasma proteins C and S are located on chromosomes 2 and 3, respectively

cDNAs encoding human proteins C and S have been used to screen a panel of mouse-human somatic cell hybrids to determine the chromosomal location of their respective genes. The gene for human protein C is located on chromosome 2, whereas that for protein S is located on chromosome 3. Analysis of human genomic DNA restriction endonuclease fragmentation patterns suggests that the human protein S gene is greater than 40 kb in size and contains a minimum of 11 introns.

Mechanisms for binocular depth sensitivity along the vertical meridian of the visual field

By removing the visual cortex unilaterally, and recording along the intact 17/18 border, we have investigated the influence of the corpus callosum on the tuning curves for stimulus disparity of cat cortical neurons. Responses to binocular stimulation were examined to movement in the same (in-phase) and in the opposite direction (antiphase) across the two retinae. In lesioned cats, as in normal cats, units were encountered which showed high sensitivity and narrow tuning for stimulus disparity. In contrast to normal cats, however, lesioned cats showed a reduced proportion of units displaying moderate binocular interactions, as well as a substantial increase in disparity-insensitive cells. The loss of disparity sensitivity after decortication was associated with a reduced incidence of both selectivity for the direction of stimulus motion and binocular activation. No large differences between the preparations were seen, however, in the ocular dominance of the total populations of cells. Differences between the normal and lesioned cats were found in binocular responses to in-phase but not to antiphase stimulation motion. Tuning curves in lesioned cats showed reduced binocular inhibition but no changes in binocular facilitation. Our findings indicate that callosal input contributes to unit disparity sensitivity by enhancing direction-selective binocular inhibition. The corpus callosum generates disparity sensitivity in a population of units in the superficial cortical layers which may play a particular role in the perception of stereoscopic depth.

Ocular dominance and disparity-sensitivity: why there are cells in the visual cortex driven unequally by the two eyes

Tuning curves for stimulus disparity were constructed for units in area 18 and along the 17/18 border of the cat visual cortex (N = 248). Units were activated with stimuli moving in the same (in-phase motion) or in the opposite direction (antiphase motion) across the two retinae. Over 70% of the units encountered showed sensitivity to stimulus disparity. A clear relationship was found between disparity-sensitivity and unit ocular dominance (OD). Contrary to what might have been expected, large binocular interactions were correlated with unilateral OD. Units highly sensitive to stimulus disparity generally showed strong dominance by one eye (OD groups 1, 2, 6 and 7), or responded well only to binocular stimulation, and weakly or not at all through each eye separately ("binocular-only"). Units unselective for stimulus disparity were usually driven well through either eye (OD groups 3, 4 and 5). High disparity-sensitivity was due to both strong binocular inhibition and strong binocular facilitation in units of extreme unilateral OD. Nearly all units of OD groups 1 and 7 showed clear binocular interactions, indicating that there are few "truly monocular" cells in the cat visual cortex.

Localization of human SAA gene(s) to chromosome 11 and detection of DNA polymorphisms

A human serum amyloid A (SAA) cDNA was used as a probe in chromosome mapping studies to detect human SAA gene sequences in DNA isolated from human/mouse somatic cell hybrids. Southern analysis of DNA from 20 hybrid cell lines, including some with translocations of human chromosomes, placed the SAA gene(s) in the p11----pter region of chromosome 11. Screening of human DNA from unrelated individuals by Southern analysis using the SAA cDNA probe revealed restriction fragment polymorphisms for HindIII and PstI. An analysis of the segregation of these polymorphisms with other markers on the short arm of chromosome 11 should more precisely map the SAA gene(s).

A time-based stereoscopic depth mechanism in the visual cortex

We propose a new depth mechanism, operating in the visual cortex, which uses temporal as well as spatial cues. By varying the timing of input to the two eyes, and the position of stimuli on the two receptive fields, we show that both temporal and spatial disparities influence the binocular responses of single cortical cells.

Effects of neonatally induced strabismus on binocular responses in cat area 18

Responses to binocular visual stimulation were compared in cortical area 18 of normal cats and in cats in which one eye was exodeviated by surgery early in postnatal life. In contrast to normal cats where most units (58%) were binocularly activated, relatively few units (10%) in strabismic cats were activated well by stimulation of either eye. Rather individual units were driven mainly via one eye or the other but not both. In addition, there was a tendency for more units to be driven well via the unoperated eye than via the exodeviated eye. Fewer cells preferring vertically oriented than horizontally oriented stimuli were found in area 18 of strabismic cats. This trend was observed for cells driven by either the normal or deviated eye and was especially marked among the small number of binocularly activated cells. Generally binocular responses and binocular interactions were found with stimulation at corresponding retinal points. In a few striking instances, however, the receptive fields of binocular neurons were located on noncorresponding retinal points at loci which would enable the cat to correlate the two images of an external object despite the large divergent strabismus. Quantitative responses to binocular stimuli presented at varied disparities and to stimuli with varied directions of motion in depth were compared in normal and strabismic cats. Despite the large strabismus, a reduced fraction of cortical neurons displayed substantial binocular interactions. In fact, binocular facilitation was as marked in the population of cells studied in strabismic cats as it was in normal animals. The major effect of strabismus was a reduction in the strength of binocular inhibition when units were tested with sideways motion. Disparity-specific responses to motion toward or away from the organism were little affected by strabismus. The degree of binocular facilitation and binocular inhibition among the cell population was similar in normal and strabismic cats. A subpopulation of units encountered in strabismic cats showed strong disparity-specific interactions for motion toward or away from the animal without equivalent modulation for sideways moving stimuli. Units with these properties were not found in normal animals and may, therefore, represent a special adaptation of the strabismic animals.