Integrated Genomic and Social Network Analyses of Severe Acute Respiratory Syndrome Coronavirus 2 Transmission in the Healthcare Setting

BACKGROUND

Infection prevention (IP) measures are designed to mitigate the transmission of pathogens in healthcare. Using large-scale viral genomic and social network analyses, we determined if IP measures used during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic were adequate in protecting healthcare workers (HCWs) and patients from acquiring SARS-CoV-2.

METHODS

We performed retrospective cross-sectional analyses of viral genomics from all available SARS-CoV-2 viral samples collected at UC San Diego Health and social network analysis using the electronic medical record to derive temporospatial overlap of infections among related viromes and supplemented with contact tracing data. The outcome measure was any instance of healthcare transmission, defined as cases with closely related viral genomes and epidemiological connection within the healthcare setting during the infection window. Between November 2020 through January 2022, 12 933 viral genomes were obtained from 35 666 patients and HCWs.

RESULTS

Among 5112 SARS-CoV-2 viral samples sequenced from the second and third waves of SARS-CoV-2 (pre-Omicron), 291 pairs were derived from persons with a plausible healthcare overlap. Of these, 34 pairs (12%) were phylogenetically linked: 19 attributable to household and 14 to healthcare transmission. During the Omicron wave, 2106 contact pairs among 7821 sequences resulted in 120 (6%) related pairs among 32 clusters, of which 10 were consistent with healthcare transmission. Transmission was more likely to occur in shared spaces in the older hospital compared with the newer hospital (2.54 vs 0.63 transmission events per 1000 admissions, P < .001).

CONCLUSIONS

IP strategies were effective at identifying and preventing healthcare SARS-CoV-2 transmission.

Real world effectiveness of tixagevimab/cilgavimab (Evusheld) in the Omicron era

BACKGROUND

Pre-exposure prophylaxis for COVID-19 with tixagevimab/cilgavimab (T/C) received Emergency Use Authorization (EUA) based on results of a clinical trial conducted prior to the emergence of the Omicron variant. The clinical effectiveness of T/C has not been well described in the Omicron era. We examined the incidence of symptomatic illness and hospitalizations among T/C recipients when Omicron accounted for virtually all local cases.

METHODS

Through retrospective electronic medical record chart review, we identified patients who received T/C between January 1 -July 31, 2022 within our quaternary referral health system. We determined the incidence of symptomatic COVID-19 infections and hospitalizations due to or presumed to be caused by early Omicron variants before and after receiving T/C (pre-T/C and post-T/C). Chi square and Mann-Whitney Wilcoxon two-sample tests were used to examine differences between the characteristics of those who got COVID-19 before or after T/C prophylaxis, and rate ratios (RR) and 95% confidence intervals (CI) were calculated to assess differences in hospitalization rates for the two groups.

RESULTS

Of 1295 T/C recipients, 105 (8.1%) developed symptomatic COVID-19 infection before receiving T/C, and 102 (7.9%) developed symptomatic disease after receiving it. Of the 105 patients who developed symptomatic infection pre-T/C, 26 (24.8%) were hospitalized, compared with six of the 102 patients (5.9%) who were diagnosed with COVID-19 post-T/C (RR = 0.24; 95% CI = 0.10-0.55; p = 0.0002). Seven of the 105 (6.7%) patients infected pre-T/C, but none of the 102 infected post-T/C required ICU care. No COVID-related deaths occurred in either group. The majority of COVID-19 cases among those infected pre-T/C treatment occurred during the Omicron BA.1 surge, while the majority of post-T/C cases occurred when Omicron BA.5 was predominant. In both groups, having at least one dose of vaccine strongly protected against hospitalization (pre-T/C group RR = 0.31, 95% CI = 0.17-0.57, p = 0.02; post-T/C group RR = 0.15; 95% CI = 0.03-0.94; p = 0.04).

CONCLUSION

We identified COVID-19 infections after T/C prophylaxis. Among patients who received T/C at our institution, COVID-19 Omicron cases occurring after T/C were one-fourth as likely to require hospitalization compared to those with Omicron prior to T/C. However, due to the presence of changing vaccine coverage, multiple therapies, and changing variants, the effectiveness of T/C in the Omicron era remains difficult to assess.

Deep Dive into the Long Haul: Analysis of Symptom Clusters and Risk Factors for Post-Acute Sequelae of COVID-19 to Inform Clinical Care

Long COVID is a chronic condition characterized by symptoms such as fatigue, dyspnea, and cognitive impairment that persist or relapse months after an acute infection with the SARS-CoV-2 virus. Many distinct symptoms have been attributed to Long COVID; however, little is known about the potential clustering of these symptoms and risk factors that may predispose patients to certain clusters. In this study, an electronic survey was sent to patients in the UC San Diego Health (UCSDH) system who tested positive for COVID-19, querying if patients were experiencing symptoms consistent with Long COVID. Based on survey results, along with patient demographics reported in the electronic health record (EHR), linear and logistic regression models were used to examine putative risk factors, and exploratory factor analysis was performed to determine symptom clusters. Among 999 survey respondents, increased odds of Long COVID (n = 421; 42%) and greater Long COVID symptom burden were associated with female sex (OR = 1.73, 99% CI: 1.16-2.58; β = 0.48, 0.22-0.75), COVID-19 hospitalization (OR = 4.51, 2.50-8.43; β = 0.48, 0.17-0.78), and poorer pre-COVID self-rated health (OR = 0.75, 0.57-0.97; β = -0.19, -0.32--0.07). Over one-fifth of Long COVID patients screened positive for depression and/or anxiety, the latter of which was associated with younger age (OR = 0.96, 0.94-0.99). Factor analysis of 16 self-reported symptoms suggested five symptom clusters-gastrointestinal (GI), musculoskeletal (MSK), neurocognitive (NC), airway (AW), and cardiopulmonary (CP), with older age (β = 0.21, 0.11-0.30) and mixed race (β = 0.27, 0.04-0.51) being associated with greater MSK symptom burden. Greater NC symptom burden was associated with increased odds of depression (OR = 5.86, 2.71-13.8) and anxiety (OR = 2.83, 1.36-6.14). These results can inform clinicians in identifying patients at increased risk for Long COVID-related medical issues, particularly neurocognitive symptoms and symptom clusters, as well as informing health systems to manage operational expectations on a population-health level.

Population-based evaluation of post-acute COVID-19 chronic sequelae in patients who tested positive for SARS-CoV-2

The true incidence and comprehensive characteristics of Long Coronavirus Disease-19 (COVID-19) are currently unknown. This is the first population-based outreach study of Long COVID within an entire health system, conducted to determine operational needs to care for patients with Long COVID.

Microbial Metabolite 3-Indolepropionic Acid Mediates Immunosuppression

The microbial-derived metabolite, 3-indolepropionic acid (3-IPA), has been intensely studied since its origins were discovered in 2009; however, 3-IPA's role in immunosuppression has had limited attention. Untargeted metabolomic analyses of T-cell exhaustion and immunosuppression, represented by dysfunctional under-responsive CD8⁺ T cells, reveal a potential role of 3-IPA in these responses. T-cell exhaustion was examined via infection of two genetically related mouse strains, DBA/1J and DBA/2J, with lymphocytic choriomeningitis virus (LCMV) Clone 13 (Cl13). The different mouse strains produced disparate outcomes driven by their T-cell responses. Infected DBA/2J presented with exhausted T cells and persistent infection, and DBA/1J mice died one week after infection from cytotoxic T lymphocytes (CTLs)-mediated pulmonary failure. Metabolomics revealed over 70 metabolites were altered between the DBA/1J and DBA/2J models over the course of the infection, most of them in mice with a fatal outcome. Cognitive-driven prioritization combined with statistical significance and fold change were used to prioritize the metabolites. 3-IPA, a tryptophan-derived metabolite, was identified as a high-priority candidate for testing. To test its activity 3-IPA was added to the drinking water of the mouse models during LCMV Cl13 infection, with the results showing that 3-IPA allowed the mice to survive longer. This negative immune-modulation effect might be of interest for the modulation of CTL responses in events such as autoimmune diseases, type I diabetes or even COVID-19. Moreover, 3-IPA's bacterial origin raises the possibility of targeting the microbiome to enhance CTL responses in diseases such as cancer and chronic infection.

Prevalence of SARS-CoV-2 infection in Baja California, Mexico: Findings from a community-based survey in February 2021 in the Mexico-United States border

Between March 2020 and February 2021, the state of Baja California, Mexico, which borders the United States, registered 46,118 confirmed cases of COVID-19 with a mortality rate of 238.2 deaths per 100,000 residents. Given limited access to testing, the population prevalence of SARS-CoV-2 infection is unknown. The objective of this study is to estimate the seroprevalence and real time polymerase chain reaction (RT-PCR) prevalence of SARS-CoV-2 infection in the three most populous cities of Baja California prior to scale-up of a national COVID-19 vaccination campaign. Probabilistic three-stage clustered sampling was used to conduct a population-based household survey of residents five years and older in the three cities. RT-PCR testing was performed on nasopharyngeal swabs and SARS-CoV-2 seropositivity was determined by IgG antibody testing using fingerstick blood samples. An interviewer-administered questionnaire assessed participants' knowledge, attitudes, and preventive practices regarding COVID-19. In total, 1,126 individuals (unweighted sample) were surveyed across the three cities. Overall prevalence of SARS-CoV-2 infection by RT-PCR was 7.8% (95% CI 5.5-11.0) and IgG seroprevalence was 21.1% (95% CI 17.4-25.2). There was no association between border crossing in the past 6 months and SARS-CoV-2 prevalence (unadjusted OR 0.40, 95%CI 0.12-1.30). While face mask use and frequent hand washing were common among participants, quarantine or social isolation at home to prevent infection was not. Regarding vaccination willingness, 30.4% (95% CI 24.4-3 7.1) of participants said they were very unlikely to get vaccinated. Given the high prevalence of active SARS-CoV-2 infection in Baja California at the end of the first year of the pandemic, combined with its low seroprevalence and the considerable proportion of vaccine hesitancy, this important area along the Mexico-United States border faces major challenges in terms of health literacy and vaccine uptake, which need to be further explored, along with its implications for border restrictions in future epidemics.

4th Generation HIV screening in the emergency department: net profit or loss for hospitals?

ABSTRACTThe objective of this study was to determine hospital costs and revenue of universal opt-out HIV ED screening. An electronic medical record (EMR)-directed, automated ED screening program was instituted at an academic medical center in San Diego, California. A base model calculated net income in US dollars for the hospital by comparing annual testing costs with reimbursements using payor mixes and cost variables. To account for differences in payor mixes, testing costs, and reimbursement rates across hospitals in the US, we performed a probabilistic sensitivity analysis. The base model included a total of 12,513 annual 4th generation HIV tests with the following payor mix: 18% Medicare, 9% MediCal, 28% commercial and 8% self-payers, with the remainder being capitated contracts. The base model resulted in a net profit for the hospital. In the probabilistic sensitivity analysis, universal 4th generation HIV screening resulted in a net profit for the hospital in 81.9% of simulations. Universal 4th generation opt-out HIV screening in EDs resulted in a net profit to an academic hospital. Sensitivity analysis indicated that ED HIV screening results in a net-profit for the majority of simulations, with higher proportions of self-payers being the major predictor of a net loss.

Designing a critical care solution using in-person and telemedicine approaches in the US-Mexico border area during COVID-19

Background

UC San Diego Health System (UCSDHS) is the largest academic medical center and integrated care network in US-Mexico border area of California contiguous to the Northern Baja region of Mexico. The COVID-19 pandemic compelled several UCSDHS and local communities to create awareness around best methods to promote regional health in this economically, socially, and politically important border area.

Purpose

To improve understanding of optimal strategies to execute critical care collaborative programs between academic and community health centers facing public health emergencies during the COVID-19 pandemic, based on the experience of UCSDHS and several community hospitals (one US, two Mexican) in the US-Mexico border region.

Methods

After taking several preparatory steps, we developed a two-phase program that included 1) in-person activities to perform needs assessments, hands-on training and education, and morale building and 2) creation of a telemedicine-based (Tele-ICU) service for direct patient management and/or educational coaching experiences.

Findings.

A clinical and educational program between academic and community border hospitals was feasible, effective, and well received.

Conclusion

We offer several policy-oriented recommendations steps for academic and community healthcare programs to build educational, collaborative partnerships to address COVID-19 and other cross-cultural, international public health emergencies.

437. Asymptomatic Healthcare Worker COVID-19 Testing Program

Background

The SARS-CoV-2 pandemic remains a major threat worldwide. Healthcare workers (HCWs) are particularly impacted by the COVID-19 pandemic with high infection rates reported from HCWs in hard-hit regions^2,3, raising concerns about nosocomial infections and the effectiveness of personal protective equipment in protecting HCWs. Asymptomatic infection is estimated 17.9% to 33.3%⁴ and is a common source of transmission⁵.

We designed a HCW testing program to address patient and employee concerns about exposures in the healthcare setting at our 808-bed health system. During the time of employee testing, the mean (range) number of inpatients with a diagnosis of COVID was 30 (22–38) of a mean (range) daily census of 560 (492–602) (approximately 5.4%).

Methods

This opt-in program offered SARS-CoV-2 testing of asymptomatic HCWs with paired nasopharyngeal or mid-turbinate swab for PCR (Roche) and serum IgG antibody testing (Diazyme). While initially designed as a pilot project in the Emergency Departments and COVID-19 units, it was quickly expanded to a health system-wide initiative.

Results

From April 22 to June 2, PCR testing was performed on 5826 asymptomatic HCWs with four PCR tests resulting positive (0.09%). Of 5589 serologic tests (anti-SARS-CoV-2 IgG) performed, 57 tested positive (1.02 %). All HCW with a positive IgG had a concurrent negative PCR.

Conclusion

In this cross-sectional evaluation, the point prevalence of SARS-CoV-2 IgG in asymptomatic HCWs at UC San Diego was less than 1%, supporting modeling estimations at the San Diego County level of very low levels of community exposure at the time of this testing.

Further analyses of incidence rates and potential risk factors such as employee roles within the healthcare system, community and healthcare exposures, and home zip code are underway.

Asymptomatic HCW testing is a strategy that can provide the perception of additional safety to both the workforce and patients as the health system reopens, while potentially reduce transmission from asymptomatic persons through active case finding and isolation.

Disclosures

Randy Taplitz, MD, Merck (Advisor or Review Panel member)

474. Using telemedicine to provide virtual care for COVID-19 patients at home

Background

In response to the COVID-19 pandemic in San Diego, California, the Infectious Disease Division at the University of California San Diego established a COVID-19 Clinic dedicated solely to managing patients safely in their homes. This strategy was developed in response to: i) concerns regarding transmission of infection in the healthcare setting, ii) avoiding overwhelming the healthcare system with COVID-19 patients, iii) providing patients with expedited access to specialists, and iv) reducing the burden on the emergency department and urgent care.

Methods

The COVID-19 clinic staff is comprised of a dedicated nurse, administrative assistant, and four infectious diseases (ID) physicians who aim to see patients within 24 hours of referral via virtual clinics 5 days a week. An ID physician initially assesses each patient in a direct telemedicine visit and answers their questions, assesses disease severity, provides both symptom management and emotional support, and education about self-isolation and transmission-based precautions. The patients are then triaged to daily nursing phone calls and follow up visits as needed.

Results

Over a period of 12 weeks (March 27 to June 16, 2020), the clinic has seen 179 patients. To assess the impact of the clinic, patients are asked to complete a 6-point verbal patients satisfaction survey after their visit. Of the 133 patients who have completed the survey to date, the vast majority reported high satisfaction with their encounters with the COVID-19 physician, with a mean score of 4.8 or higher on all six questions (on a scale of 1 to 5). When asked “Did you feel comfortable talking to your COVID-19 ID physician?” on a scale of 1 to 5, the average score was 4.9. When asked “Did the physician do a good job answering your questions?” the average was 4.9. Patients reported feeling safer after talking with their physician (mean score 4.8), and felt better educated on how to self-quarantine at home (mean score 4.85) and when to seek care from an emergency room, urgent care or hospital (mean score 4.83).

Conclusion

The UCSD COVID-19 Clinic demonstrates how telemedicine can be utilized in response to a public health crisis by creating a virtual clinic to provide ID care for patients in their homes.

Disclosures

All Authors: No reported disclosures

Endotheliopathy and Platelet Dysfunction as Hallmarks of Fatal Lassa Fever

Lassa fever (LF) causes multisystem disease and has a fatality rate <70%. Severe cases exhibit abnormal coagulation, endothelial barrier disruption, and dysfunctional platelet aggregation but the underlying mechanisms remain poorly understood. In Sierra Leone during 2015-2018, we assessed LF patients' day-of-admission plasma samples for levels of proteins necessary for coagulation, fibrinolysis, and platelet function. P-selectin, soluble endothelial protein C receptor, soluble thrombomodulin, plasminogen activator inhibitor 1, ADAMTS-13, von Willebrand factor, tissue factor, soluble intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 were more elevated in LF patients than in controls. Endothelial protein C receptor, thrombomodulin, intercellular adhesion molecule 1, plasminogen activator inhibitor 1, D-dimer, and hepatocyte growth factor were higher in fatal than nonfatal LF cases. Platelet disaggregation occurred only in samples from fatal LF cases. The impaired homeostasis and platelet dysfunction implicate alterations in the protein C pathway, which might contribute to the loss of endothelial barrier function in fatal infections.

1618. Public Health at the United States/Mexico Border: Evaluation of the County of San Diego Health and Human Services Agency’s Health Screening Assessment of Asylum-Seeking Families at the San Diego Rapid Response Network Shelter

Background

Many families arrive at the United States–Mexico border seeking asylum. Jewish Family Service and the San Diego Rapid Response Network operate a shelter in San Diego that provides shelter, food, clothing, legal services and travel coordination for asylum-seeking families. Two local federally qualified health centers provide on-site urgent care.

Methods

In late December 2018, the County of San Diego expanded public health efforts by conducting health screenings of guests upon entry to the shelter with the goal of identifying health issues requiring urgent or emergent evaluation and preventing the spread of communicable disease. University of California San Diego Health physicians contracted by the County of San Diego Health and Human Services Agency (HHSA) nurses and ancillary staff provide daily on-site services to all shelter entrants including: health screening for diseases of public health significance, treatment and/or referral of urgent conditions, and medical clearance for shelter entry or medical isolation as needed. Official tracking of screening outcomes from January 2 to April 24, 2019 were collected using standardized surveys and analyzed for program evaluation and surveillance purposes.

Results

During that time a total of 9,124 asylum-seekers were screened, averaging 81 guests daily, identifying: 42 influenza-like illness, 645 lice, 330 scabies, 8 varicella, and 0 hepatitis A cases. Chest radiography for suspected tuberculosis was performed for 29 guests. Only one chest x-ray was abnormal. Sputum specimens for acid-fast stain (n = 3) and nucleic acid testing (n = 2) were all negative and no tuberculosis cases were diagnosed. Emergency department referrals were made for <1% of guests (n = 90) for conditions including pregnancy complications, asthma, dysentery, hemoptysis and fractures. No deaths or outbreaks of communicable disease occurred.

Conclusion

Coordination among local partner agencies resulted in early identification of communicable and acute health conditions prior to shelter entry allowing evaluation, treatment and off-site isolation, and minimizing stress on the emergency medical services system. This approach provides a successful model for health screening of asylum-seeking families arriving at the United States–Mexico border.

Disclosures

All authors: No reported disclosures.

Universal HIV and Birth Cohort HCV Screening in San Diego Emergency Departments

Universal HIV and HCV screening in emergency departments (ED) can reach populations who are less likely to get tested otherwise. The objective of this analysis was to evaluate universal opt-out HIV and HCV screening in two EDs in San Diego. HIV screening for persons aged 13-64 years (excluding persons known to be HIV+ or reporting HIV testing within last 12 months) was implemented using a 4th generation HIV antigen/antibody assay; HCV screening was offered to persons born between 1945 and 1965. Over a period of 16 months, 12,575 individuals were tested for HIV, resulting in 33 (0.26%) new HIV diagnoses, of whom 30 (90%) were successfully linked to care. Universal screening also identified 74 out-of-care for >12-months HIV+ individuals of whom 50 (68%) were successfully relinked to care. Over a one-month period, HCV antibody tests were conducted in 905 individuals with a seropositivity rate of 9.9% (90/905); 61 seropositives who were newly identified or never treated for HCV had HCV RNA testing, of which 31 (51%) resulted positive (3.4% of all participants, including 18 newly identified RNA positives representing 2% of all participants), and 13/31 individuals (42%) were linked to care. The rate of newly diagnosed HCV infections exceeded the rate of newly diagnosed HIV infections by >7-fold, underlining the importance of HCV screening in EDs.

Actinotignum schaalii Infection: A Clandestine Cause of Sterile Pyuria?

Actinotignum schaalii is an underappreciated cause of urinary tract infections (UTIs) in older adults. The diagnosis may be missed due to difficulty isolating and identifying the organism. Complications can result because the organism is intrinsically resistant to 2 commonly used drugs to treat UTI, as illustrated by this case.

Generalization of aggressive behavior in adolescent delinquent boys

The generalization of conditioned aggressive and nonaggressive responses in a group of six adolescent delinquent boys was investigated. Responses were reinforced in card games where a token reinforcement system with money as a back-up rinforcer was used. Conditioning of responses was rapid. Generalization, measured in terms of frequency of physical contact, was tested in a group game for which no reinforcement was given. Generalization occurred during aggressive contingencies. During nonaggressive contingencies, responses did not return completely to the baseline level.

The yeast hsp70 homologue Ssa is required for translation and interacts with Sis1 and Pab1 on translating ribosomes

The 70-kDa heat shock proteins are molecular chaperones that participate in a variety of cellular functions. This chaperone function is stimulated by interaction with hsp40 proteins. The Saccharomyces cerevisiae gene encoding the essential hsp40 homologue, SIS1, appears to function in translation initiation. Mutations in ribosomal protein L39 (rpl39) complement loss-of-function mutations in SIS1 as well as PAB1 (poly(A)-binding protein), suggesting a functional interaction between these proteins. However, while a direct interaction between Sis1 and Pab1 is not detectable, both of these proteins physically interact with the essential Ssa (and not Ssb) family of hsp70 proteins. This interaction is mediated by the variable C-terminal domain of Ssa. Subcellular fractionations demonstrate that the binding of Ssa to ribosomes is dependent upon its C terminus and that its interaction with Sis1 and Pab1 occurs preferentially on translating ribosomes. Consistent with a function in translation, depletion of Ssa protein produces a general translational defect that appears similar to loss of Sis1 and Pab1 function. This translational effect of Ssa appears mediated, at least in part, by its affect on the interaction of Pab1 with the translation initiation factor, eIF4G, which is dramatically reduced in the absence of functional Ssa protein.

The cyclin box and C-terminus of cyclins A and E specify CDK activation and substrate specificity

The cyclins and their catalytic partners, the Cyclin Dependent Kinases (CDKs), are essential for progression through the cell cycle. Cyclin/kinase complexes containing cyclins A or E are active primarily in late G1 to S phase and both have been shown to phosphorylate histone H1 and the retinoblastoma gene product (pRb) in vitro. Despite these similarities, cyclins A and E display differences in CDK activation and substrate specificity. We find that in vitro, cyclin E/CDK2 and cyclin A/CDK2 phosphorylate histone H1 similarly but only cyclin A/CDK2 phosphorylates lamin B. While both cyclin A and cyclin E bind CDK1 efficiently, only cyclin A activates CDK1 kinase activity. Using chimeric proteins between cyclins A and E we find that both the cyclin box and C-terminus of cyclins A and E are required for CDK binding, activation and targeting of substrate specificity.

G1 cyclins control the retinoblastoma gene product growth regulation activity via upstream mechanisms

Inactivation of the retinoblastoma gene product (pRb) occurs concomitant with the appearance of its hyperphosphorylated form in mid to late G1. Multiple cyclin/CDK complexes are implicated in the cell cycle phosphorylation of pRb. Using in vivo expression systems, we show that cyclins A, E, D1, D2, and D3 each function to phosphorylate and inactivate pRb. In vivo, G1 cyclin/kinase complexes enhance the phosphorylation of pRb, and these effects of cyclin/kinases on pRb can be overcome by the addition of p21, a wide spectrum inhibitor of G1 kinases. Kinases associated with cyclins A, E, and D1 phosporylate pRb indistinguishably in vivo, according to proteolytic maps. Although cyclin D1 has been reported to bind to pRb directly, requiring the pRb-binding motif LXCXE, a mutant D1 lacking the pRb-binding motif remains able to phosphorylate pRb in vivo and in vitro and is also able to reverse the growth-inhibitory properties of pRb in intact cells. Finally, coexpression of G1 cyclins and kinases represses pRb-mediated growth inhibition in Saos-2 cells. The multiplicity of mechanisms for pRb phosphorylation and inactivation suggests that several pathways exist for the regulation of pRb by phosphorylation.

Time-course and steroid specificity of aromatase induction in rat hypothalamus-preoptic area

We studied the time-course and steroid specificity for aromatase induction in the hypothalamus-preoptic area (HPOA) of the adult male rat. Aromatase activity (AA) was measured in tissue homogenates by using a radiometric assay that quantifies the stereospecific production of 3H2O from [1 beta-3H] androstenedione. We found that by 48 h after administration of testosterone, HPOA AA was significantly (p less than 0.01) greater than control values in castrated rats. In contrast, AA was significantly (p less than 0.01) reduced 12 h after castration, and reached its lowest levels by 4 days after castration. Several other steroids, administered in 3-cm Silastic capsules for 7 days, were tested for their capacity to induce hypothalamic AA. In addition to testosterone, only 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 alpha, 17 beta-diol were effective. Neither the stereoisomers of these compounds nor several other steroids, including estradiol, progesterone, and corticosterone, were active. This profile of activity indicates that the induction of HPOA AA is androgen-specific and, together with the demonstrated time-course of induction, lends further support to the hypothesis that androgens regulate AA through a receptor mechanism and the synthesis of new protein.

Regulation of androgen metabolism and luteinizing hormone-releasing hormone content in discrete hypothalamic and limbic areas of male rhesus macaques

The conversion of androgens to active metabolites by neural tissue is believed to be an essential component in the cellular mechanism of androgen-induced neuroendocrine responses. In this study, we measured the in vitro aromatization and 5 alpha-reduction of androgens in incubations of microdissected brain regions from four intact and five castrated (6 weeks) adult male rhesus monkeys. Individual nuclei were microdissected from 600-microns frozen brain sections and homogenized in a potassium phosphate buffer. Aromatase activity was measured by a radiometric assay that uses the incorporation of tritium from [1 beta-3H]androstenedione into 3H2O as an index of estrogen formation. We estimated 5 alpha-reductase activity by isolating 5 alpha-dihydrotestosterone on two different chromatography systems and measuring the amount of this product formed from [1 alpha,2 alpha-3H]testosterone. We acidified a portion of each homogenate and determined LHRH content by RIA. Between brain nuclei, aromatase activity varied 1500-fold, whereas 5 alpha-reductase activity varied only 3-fold. Both enzyme activities were highest in amygdaloid, medial preoptic, and medial diencephalic nuclei and lowest in the caudate nucleus. Aromatase activities in the supraoptic nucleus, periventricular area, medial preoptic area-anterior hypothalamus, and lateral hypothalamus were significantly (P less than 0.05) lower in castrated males. Castration did not significantly affect 5 alpha-reductase activity, except for an increase in the basolateral amygdala. The highest concentrations of LHRH were in the infundibular nucleus-median eminence and were 30 times greater than amounts measured in preoptic and medial hypothalamic nuclei. The LHRH contents of the infundibular nucleus-median eminence, ventral medial nucleus, and lateral hypothalamus were significantly lower in castrated males (P less than 0.05). In addition, we observed a significant correlation between aromatase activity and LHRH content in the basal hypothalamus of intact males (r = 0.947; P less than 0.05; n = 8), but not in the preoptic-anterior hypothalamus (r = 0.068; P greater than 0.05; n = 10). No correlation was observed between 5 alpha-reductase activity and LHRH content in either area. These data indicate that castration selectively affects androgen metabolism and LHRH content in discrete regions of the brain of male monkeys and suggest that aromatase and 5 alpha-reductase are regulated differentially in the primate brain.

Distribution and regulation of aromatase activity in the rat hypothalamus and limbic system

Conversion of androgen to estrogen in the rat brain is catalyzed by aromatase enzymes. The maximum concentrations of these enzymes are found within the hypothalamus and amygdala, where they appear to play an important role in the process by which androgens affect both behavior and neuroendocrine function. In the present study, we measured the levels of aromatase activity (AA) in 20 nuclei and brain regions of the adult rat brain. Individual nuclei were microdissected from 600-micron frozen sections. Tissues from 3 animals were pooled, and AA was measured by an in vitro radiometric assay that quantifies the stereospecific production of 3H2O from [1 beta-3H]androstenedione as an index of estrogen formation. We report that AA is heterogeneously distributed within the rat brain. The greatest amounts of activity were found in the bed nucleus (n.) of the stria terminalis (700 protein fmol/h . mg) and in the medial (MA) and cortical amygdala (400-600 fmol/h . mg protein) of the male. There was an evident rostral-caudal and medial-lateral gradient in AA throughout the diencephalon. Activity was high in the periventricular preoptic n. and medial preoptic n.; intermediate in the suprachiasmatic preoptic n., anterior hypothalamus, periventricular anterior hypothalamus, and ventromedial n.; and low in the arcuate n.-median eminence, lateral preoptic n., supraoptic n., dorsomedial n., and lateral hypothalamus. Regions devoid of measurable AA included the medial and lateral septum, caudate-putamen, hippocampus, and parietal cortex. In the female, AA was greatest in the MA and cortical amygdala. We found that AA in the MA, stria terminalis n., suprachiasmatic preoptic n., periventricular preoptic in., medial preoptic n., anterior hypothalamus, and ventromedial n. was significantly greater (P less than 0.05) in males than in females. Orchidectomy reduced AA to levels seen in females, and administration of testosterone to castrated males restored AA in these areas. No significant sex differences were observed in any other hypothalamic or amygdaloid nuclei, although AA was increased by testosterone treatment in the periventricular anterior hypothalamus, arcuate n.-median eminence, and lateral hypothalamus. Our results provide a quantitative profile of AA in specific hypothalamic and limbic nuclei of the rat brain as well as information on the control of AA within these discrete regions.

Experimental induction of estradiol positive feedback in intact male monkeys: absence of inhibition by physiologic concentrations of testosterone

Estradiol benzoate (E2B) induces an increase in serum luteinizing hormone (LH) in gonadectomized macaques of both sexes and in intact females but not males. To determine the interaction of testosterone (T) with E2B, we treated 6 intact male cynomolgus macaques as follows: 1) with E2B alone; 2) E2B after pretreatment with estradiol-17 beta (E2) for 2 wk; and 3) Treatment 2 plus exogenous T along with the E2. In Experiment 4, 6 female cynomolgus macaques were treated with large doses of T for 10 days prior to E2B. Serum levels of T and E2 were quantified by radioimmunoassay; LH by bioassay. In Experiment 1, LH decreased from 5.20 +/- 0.95 micrograms/ml (mean +/- SEM) to 0.47 +/- 0.04 micrograms/ml. In Experiment 2, E2 pretreatment depressed LH and T, and these animals responded to E2B with an increase in LH. Replacement of T (Experiment 3) did not inhibit positive feedback. Intact females treated with T responded to E2B with an increase in LH. These results suggest that a testicular product other than T is involved in the inhibition of the positive feedback response to E2B in intact male macaques, and that E2 pretreatment overcomes this effect.

Small doses of human chorionic gonadotropin prevent estradiol-induced luteolysis

The manner in which exogenous 17 beta-estradiol (E2) induces premature luteolysis in primates is unclear. In an effort to determine whether exogenous luteotropic hormone inhibits E2-induced luteolysis, E2 capsules were implanted subcutaneously in 11 cynomolgus macaques during the early luteal phase; six animals received injections of human chorionic gonadotropin (hCG; 7.5, 10, or 15 IU/day) for 10 days, and the remaining monkeys received saline. Blood was collected once daily for measurement of E2, progesterone, and bioactive luteinizing hormone (LH). Peak progesterone concentrations were between 0.7 and 5.0 ng/ml and declined prematurely in monkeys given E2 plus saline; the luteal phase was 11.5 +/- 0.6 days (mean +/- SE). With E2 plus hCG treatment, serum progesterone continued to increase after E2 capsule placement and reached peak levels of 4.0-13.0 ng/ml; the luteal phase was 15.3 +/- 0.5 days. Therefore, E2-induced luteolysis was overcome by concurrent administration of hCG. These results suggest that exogenous tropic hormone circumvents the inhibitory influence of E2 on luteal function, but the details of the interaction remain unknown.

Effects of progesterone on estrogen-induced gonadotropin release in male rhesus macaques

The effects of progesterone (P) on estrogen (E)-induced gonadotropin release were studied in 10 adult male rhesus macaques castrated more than 2 yr earlier. The intent was to determine whether physiological levels of P (approximately 400 pg/ml) found in the systemic circulation of intact males would block E-induced gonadotropin release and whether the responses of castrated males were similar to those of castrated females with and without pretreatment with 17 beta-estradiol (E2). Different doses of P were administered in Silastic capsules (0.3, 4.0, and 5.0 cm) implanted sc. A 0.3-cm implant maintained serum P levels at about 400 pg/ml (equivalent to physiological levels in intact males); 5.0-cm implants produced serum levels of about 4.0 ng/ml (similar to luteal phase levels in females). In male monkeys treated for approximately 3 weeks with E2, only the highest dose (approximately 4.0 ng/ml) of P blocked FSH induced by estradiol benzoate (E2B). LH was blocked in one third of the animals thus treated. The same P dose was ineffective in blocking E2-induced LH release in spayed females pretreated with E2, but did block FSH release. Gonadectomized males and females not treated beforehand with E2 released LH in response to an E2B challenge, but FSH was not elevated in the peripheral circulation under these experimental conditions. These results suggest that luteal phase levels of P block E2-induced FSH release in gonadectomized males and females. With the same treatment regimens, P blocks E2 action in some males, but all females responded to E2B by releasing LH. These data also suggest that estrogen priming is necessary for FSH, but not LH, release in adult rhesus macaques of both sexes. The prerequisite of E treatment for the induction of positive feedback appears to be associated with the level of gonadotropin suppression before E2B treatment.

The boys in the club

A historical perspective of men in dietetics. The pioneer spirit of Lenna Cooper is exemplified in the gradual emergence of the male dietitian. It was not an easy task for the early female dietitian to accept the concept of male membership. From the acceptance of the first known qualified male dietitian in 1921 and of the first male intern in 1934 to the final acceptance of male dietitians in the U.S. Army in the early 1950s, there is recorded female resistance. As the status of the profession grew, so did men's interest in it.