Short-Term Changes in Vasectomy Consults and Procedures Following Dobbs v Jackson Women's Health Organization

INTRODUCTION

On June 24, 2022, the US Supreme Court issued its decision on Dobbs v Jackson Women's Health Organization (Dobbs). This decision had major implications on female reproductive choices, but also had potential implications on their male counterparts. We sought to determine the association of Dobbs with the number and characteristics of men seeking vasectomy.

METHODS

A retrospective review was performed to determine the number of vasectomy consults and procedures completed at a single Michigan health system in the 6 months following Dobbs (June 24, 2022-December 24, 2022) vs the same 6-month time frame between 2019 and 2021. Another retrospective review was conducted in the 3 months following Dobbs (June 24, 2022-September 24, 2022) vs the same days in 2021 to determine the number of vasectomy consults completed and to evaluate for differences in the characteristics of these men.

RESULTS

In the 6 months after Dobbs, there was a 150% and 160% increase in vasectomy consults and procedures completed, respectively, compared to a similar time frame in 2019 to 2021. In the 3 months after Dobbs, there was a 225% increase in new vasectomy consults compared to a similar time frame in 2021. There were no differences in the age, race, religion, median household income, or insurance type of men seeking vasectomy consult pre- vs post-Dobbs. Partnerless men (odds ratio 3.66) and those without children (odds ratio 2.85) were more likely than married men and those with 3 or more children, respectively, to seek vasectomy consult post-Dobbs.

CONCLUSIONS

Dobbs was associated with a marked increase in vasectomy consultations and procedures at our institution in the state of Michigan. Future studies are needed to determine the long-term implications of Dobbs on vasectomy practices and determine if vasectomy practices differ by states and their respective abortion laws.

Outcomes of Prolonged Open Abdomen in Children

INTRODUCTION

We sought to better characterize outcomes in pediatric patients requiring open abdomen for instability with ongoing resuscitation, second look surgery, or left in discontinuity or congenital or acquired loss of domain that may lead to prolonged open abdomen (POA) or difficulties in successful abdominal wall closure.

METHODS

We performed a single-institution retrospective review of patients aged less or equal to 18 years who presented to our institution from 2015 to 2022. We defined POA as requiring three or more surgeries prior to abdominal wall closure. Descriptive statistics were performed using median and interquartile range.

RESULTS

Median age was 15 years (interquartile range 0-6 years), 46% female, and 69% White. Survival rate was 93% for the entire cohort. The most common indication for open abdomen was second look/discontinuity 22/41 (54%). The most common temporary abdominal wall closure was wound vac (43%). Fifty eight percent patients achieved primary tissue closure, the remaining required mesh. Of the 42 patients, 25 required POA. They had increasing rate of secondary infections at 56% compared to 44% (P = 0.17). The groups were further divided into indications for open abdomen including ongoing resuscitation, second look/discontinuity, and loss of domain with similar outcomes.

CONCLUSIONS

In the largest series of long-term outcomes in pediatric patients with an open abdomen, we found that a majority of children were able to be primarily closed without mesh despite the number of surgeries required. Further studies require a protocolized approach to improve the long-term outcomes of these patients.

Implementation of Standardized Educational Material in Outpatient Pediatric Surgery: A Pilot Study

INTRODUCTION

Caregiver health literacy is affected by both personal knowledge and education provided by clinicians. Literature on implementation of educational materials into pediatric surgical clinical practice is scarce. We developed plain-language picture-based educational material and implemented it in a pediatric surgery clinic. We assessed both caregiver and clinician satisfaction before and after implementation.

METHODS

Picture-based educational material was developed for epigastric/umbilical/inguinal hernias/hydroceles, gastrostomy/gastrojejunostomy tube creation, and soft tissue masses and implemented in an academic pediatric surgery clinic. Pediatric surgeons (n = 12), clinic nurses (n = 4), and physician extenders (n = 2) were surveyed before and after a 4-week pilot implementation period. In parallel, parents of children (0-18 y) completed a 19-item postpre electronic survey capturing demographics, self-professed level of prior knowledge, and opinions regarding the material. Descriptive statistics were performed.

RESULTS

Clinician response rate was 88% (pre) and 72% (post). Preimplementation, clinicians overwhelmingly reported repetitive parental counseling, need to redraw diagrams, and anticipation of improvement in workflow with standardized materials. Postimplementation, most clinicians felt the material was easy to use (76%), beneficial (77%), and perceived satisfaction in parents they were counseling (77%). Caregiver response rate was 100%. The majority reported their understanding improved after reviewing the material, found the material easy to understand and helpful, were more comfortable managing their child's condition, and recommended continued use of the material during visits.

CONCLUSIONS

Results indicate clinician satisfaction and willingness to use standardized educational material during outpatient visits, as well as caregiver satisfaction and self-reported improved understanding. These findings support further development and use of standardized educational material for pediatric surgical conditions and procedures.

Applying Best Practice to Converting Blood Collection Tube Suppliers: Overcoming Laboratory Supply Shortages

Introduction/Objective

Changing blood tube suppliers is a complex process that requires systematic validation. It can serve to expand a laboratory’s options during a supply shortage, and can lead to cost savings. Just prior to the pandemic, our laboratory underwent a large-scale conversion of blood tube suppliers after successful validation of serum, plasma, and whole blood tubes for blood bank, chemistry, immunology, hematology, coagulation, molecular diagnostics, and flow cytometry.

Methods/Case Report

First, we designed a patient consent form for collecting extra blood samples. Per CLSI standards, validation of blood tubes is needed for each testing methodology but not for each analyte. Hence, we selected high-impact assays to represent each testing methodology used by our instrument platforms. We designed comparison studies to test the new blood tubes for result accuracy, precision and specimen stability that covered an assay’s reportable range. Allowable error limits were set based on Westgard and CAP guidelines. Spiked specimens were used when positive patient samples were not feasible. We also took the opportunity to optimize the blood tube sizes, e.g., converting the lavender-top tubes from 2 ml (vendor A) to 3 ml (vendor B). We then confirmed with our reference labs the acceptability of the new vendor’s products, and administered an electronic survey to solicit staff feedback. Finally, we coordinated supply chain, formulary changes and test catalog updates.

Results (if a Case Study enter NA)

Data analyses showed 100% acceptable performance of the new supplier’s blood tubes. The survey showed that our phlebotomists supported the new products, citing their ease of use and good vacuum. Our hematology technologists provided favorable feedback on the larger lavender-top tubes that reduced the number of insufficient samples. On the economic front, this supplier conversion has yielded a 26% cost savings.

Conclusion

To our knowledge, our study is the most comprehensive of all blood collection device comparison analyses published. Our validation strategies that were designed to comply with best practice standards have led to our confidence in the interchangeability of the new and old blood tube products. This initiative serves to elucidate a protocol to add vendor options that can be replicated by other laboratories to mitigate blood tube supply shortages and backorders. It has helped us control supply costs without compromising quality.

Evaluation of the performance of breast cancer cell line–derived multigene predictors of chemotherapy response in multiple clinical trials

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Background: While various multi-gene predictors (MGPs) of chemotherapy response have been developed based on cancer patient primary tissues or cancer cell-lines, the accuracy and consistency of these predictors remain a concern in clinical validation studies. In this study we developed four unique MGPs for chemotherapy response from breast cancer cell lines and performed a systematic evaluation of the performance of these MGPs using data from five distinct clinical trials.

Methods: Forty-six immortalized breast cancer cell-lines were exposed to various concentrations of drug combinations [paclitaxel, 5-fluorouracil, doxorubicin, cyclophosphamide (TFAC); 5-fluorouracil, doxorubicin, cyclophosphamide (FAC); 5-fluorouracil, epirubicin, cyclophosphamide (FEC) and epirubicin, cyclophosphamide (EC)] using an in vitro chemosensitivity assay. Utilizing publicly available breast cancer cell-line microarray data, genes highly associated with in vitro chemosensitivity were selected as candidate MGPs. Five independent and publicly available clinical trials were used for validation. In three of these clinical trials patients were treated by TFAC, while EC, FAC or FEC were used in the other two trials. All five studies involved neoadjuvant chemotherapy treatment, and pathologic complete response (pCR) was used as the endpoint. The association of MGPs with pCR was assessed using receiver-operator curve (ROC) analysis and area under the ROC (AUC) was used to evaluate the performance of prediction.

Results: In five independent clinical trials, the MGPs predicted patient pCR to EC, FAC/FEC and three TFAC treatments with an AUC of, 0.671, 0.632, 0.735, 0.738 and 0.647 respectively.

Conclusions: In the five independent clinical trials in which patients were treated by various chemotherapy agents, the performance of MGPs is promising. These results demonstrate the feasibility of using breast cancer cell-line derived MGPs to predict breast cancer patients’ chemotherapy responses.

Abstract P3-08-02: Pharmacogenomic Predictors of Patient Response to Chemotherapy Derived from Breast Cancer Cell Lines Combining Knowledge-Based and Data-Driven Methods

Background: Responses of breast cancer patients to chemotherapy treatments vary considerably, and population treatment response rates remain low. To improve patient outcomes, genomic profiles have been used to identify patients who would benefit from specific treatments. Several studies have used cancer cell lines to develop pharmacogenomic predictors by identifying genes associated with drug response. However, pharmacogenomic predictors derived by this data-driven approach may not readily elucidate the underlying mechanisms associated with drug responses, because the identified predictors by computational methods may not directly associate with drug responses considering the complex genetic regulatory network. To overcome this issue, we proposed a strategy to integrate data-driven methods with biological knowledge-based approaches to identify genomic predictors. We then applied this approach to breast cancer cell lines to identify genomic predictors of paclitaxel-5-fluorouracil-doxorubicin-cyclophosphamide (TFAC), the identified predictors are then evaluated by their ability to predict the clinical outcome of the breast cancer patients who are treated by TFAC. Material: Thirty immortalized breast cancer cell lines were exposed to various concentrations of TFAC using a chemosensitivity assay. Area under the dose-response curves was calculated to measure chemoresponses. Gene expression profiles of the 30 cell lines, the expression profiles as well as the pathologic complete response (pCR) information of 133 breast cancer patients treated by TFAC were publicly available. Methods: We performed pathway enrichment analysis in breast cancer cell lines to assess the association between drug response and curated gene sets predefined by molecular signature database. Pathways with p-value less than 0.01 were considered enriched. The genes from the enriched pathways whose expression values were highly correlated with drug sensitivity were selected as the pharmacogenomic predictors. To validate these predictors, the performances of their prediction for patients’ pCR were evaluated using principle component regression method.

Results: Using pathway enrichment analysis, 17 pathways were identified to be related to TFAC drug response. These pathways are related to different biological functions, including breast cancer ER status and BRCA type, immune response, differentiation, and drug response. Using supervised principal component regression, 59 genes involved in at least one of these 17 pathways were selected as genomic predictors. The prediction accuracy of patient pCR was 0.70, sensitivity was 0.71, and specificity was 0.70. Conclusion: By combining knowledge-based and data-driven methods, we have identified 59 genes from breast cancer cell lines as pharmacogenomic predictors of drug response to TFAC. These results support the viability of using breast cancer cell lines to predict breast cancer patient response to chemotherapy. Further functional study of these pharmacogenomic predictors will extend our understanding of individual drug response and facilitate personalized treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-08-02.

Abstract P2-09-10: Feasibility Assessment of Pharmacogenomic Predictors Developed from Breast Cancer Cell Lines To Predict Breast Cancer Patient Pathological Response in Neoadjuvant Chemotherapy

Background: Studies of developing pharmacogenomic predictors from cancer cell lines to predict cancer patient clinical response and outcome to chemotherapy have yielded both positive and negative results. The variability in these results may arise from the noise inherent of microarray technology as well as the small sample size of in cell line studies. Therefore, it is greatly needed to evaluate the feasibility of using cell lines to develop pharmacogenomic predictors of patient pathological response. Material and Methods: Thirty breast cancer cell lines were exposed to 10 concentrations of paclitaxel-5-fluorouracil-doxorubicin-cyclophosphamide (TFAC) to measure in vitro chemosensitivity. Two independent and publicly available microarray datasets (Hoeflich and Neve) on these breast cancer cell lines together with the chemosensitivity results were used to identify pharmacogenomic predictors from each dataset. Two independent clinical trials (Hess and Popovici) with publically available data, having 130 and 100 patients respectively, were used as test sets to validate the accuracy of the pharmacogenomic predictors. All patients received TFAC as neoadjuvant therapy and the gene expression profiles of patients were assessed before receiving chemotherapy treatment. The patient's pathological complete response (pCR) was determined after treatment to evaluate the chemotherapy efficacy.

The pharmacogenomic predictors developed from each of the cell line studies were evaluated for their ability to predict patient pCR in each of the clinical trials using the supervised principle component regression method.

Results: The pharmacogenomic predictors identified from the Hoeflich and Neve cell line data (training sets) predicted pCR of the patients in the two clinical trials (test sets) with 64%-68% accuracy, 70%-87% sensitivity, and 60%-67% specificity when 100 genes were selected as pharmacogenomic predictors (Table 1).

Conclusions: The four independent prediction results generated in this study demonstrate the feasibility of using breast cancer cell lines to identify pharmacogenomic predictors of response to chemotherapy treatment for breast cancer patients. Future studies will examine the use of drug responses from primary cultures of patient tumors to develop pharmacogenomic predictors of breast cancer patient responses to chemotherapy treatment.

Table 1. Prediction of breast cancer patients’ pCR by pharmacogenomic predictors derived from breast cancer cell lines.

Prediction of Response to Paclitaxel by ChemoFx assay Correlates with Estrogen Receptor Status and Changes in Apoptosis Pathway in Human Breast Cancers

Background: Paclitaxel belongs to the taxane family of therapeutics, which have emerged as critically important drugs for breast cancer treatment. In addition to inhibiting cell growth by interfering with microtubule disassembly, its mechanism of action also includes induction of apoptosis. Recent studies suggest that besides being a key predictor for endocrine therapy response, Estrogen Receptor (ER) status also influences sensitivity of breast cancer to paclitaxel, with ER negative tumors being more responsive to the drug.Methods: The ChemoFx live cell chemoresponse assay was performed on 25 breast cancer cell lines (10 ER+ and 15 ER-). These cells were treated with a range of 10 doses of paclitaxel for 72 hours before DAPI staining of nuclei and counting. AUC (Area Under Curve) values were calculated and additional statistical analysis was performed on the resulting dose-response curves. Differential gene expression analysis was conducted to compare ER+ (n=82) and ER- (n=51) breast cancer patients using a public Microarray database. In addition, 2 of the 25 breast cancer cell lines, T47D (ER+) and SKBR3 (ER-), were treated with paclitaxel, lysed, and analyzed with Western blotting to detect cleaved caspase-3 and cleaved PARP expression, with beta-actin employed as a normal control.Results: The ChemoFx assay results revealed that none of the ER+ cells were categorized as R (responsive) to paclitaxel, with seven NR (non-responsive) and one IR (intermediate responsive). On the contrary, of the 15 ER- cell lines, three were categorized as R, only four were categorized as NR, and eight were categorized as IR. Statistical analysis suggested that paclitaxel responsiveness based on ChemoFx assay correlates with ER status (Chi-square test, p<0.05), with ER- breast tumors being more responsive to paclitaxel. Microarray analysis revealed differential expressions of genes implicated in the apoptosis pathway (q< 0.05) in ER+ and ER- breast cancers. Western blot analysis showed that paclitaxel induced cleaved caspase-3 and cleaved PARP expressions, both of which are indicators of activation of apoptosis, in SKBR3 cells (ER-), but not in T47D cells (ER+).Conclusions: ER status appears to predict in part, the response of breast cancer cells to paclitaxel as determined by the ChemoFx assay. ER-negative breast cancer cells are more likely to be responsive, which is consistent with established clinical findings. Our assay also distinguishes between NR/IR and R to paclitaxel within the ER- population. Similar ChemoFx assays are being performed on primary cultures from ER+ and ER- breast cancer patient specimens. Results from RNA microarray and Western blot analyses indicate that differences in gene expression in the apoptosis pathway, and in activation of apoptosis pathway, namely changes in expressions of cleaved PARP and cleaved caspase-3 in response to paclitaxel, may explain differences in the responsiveness of ER+ and ER- breast cancers to paclitaxel. This also suggests a potential role of cleaved PARP and cleaved caspase-3 as biomarkers in addition to ER for prediction of paclitaxel responsiveness in breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2028.

Recruiting and selecting generalist-oriented students at Pennsylvania State University College of Medicine

The authors describe the strategies developed at the Pennsylvania State University College of Medicine, as part of The Robert Wood Johnson Foundation's Generalist Physician Initiative, to increase the proportion of graduating medical students entering generalist disciplines. These strategies included modifying the admission process to involve more primary care faculty so that students with identified potential for primary care would make up at least half of each entering class, and partnering with selected colleges and universities in Pennsylvania to increase the number of applicants with the potential for primary care. They describe partnering and outreach programs--Primary Care Day, off-campus cluster meetings, and the Primary Care Scholars Program for college seniors--and present promising information about the results.

Excess coffee consumption in simulated complex work settings: detriment or facilitation of performance?

Twenty-four managers who normally consume between 400 and 1,000 mg of caffeine per day participated in all-day quasi-experimental simulations. In a crossover, doubleblind design, they made complex managerial decisions either on treatment with their typical daily dose of caffeine or on treatment with 400 mg of caffeine in excess of daily consumption. The effect of caffeine treatment on various validated performance indicators was investigated. The impact of excess caffeine consumption was mild. Increased caffeine facilitated speed of response to incoming information but decreased utilization of opportunity. No significance was obtained for other measures of managerial effectiveness (such as activity, breadth, strategy, and emergency response).

Alcohol hangover and managerial effectiveness

Twenty-one male managers who normally drink moderate amounts of alcohol participated in a placebo-controlled, double-blind, cross-over experiment. Subjects consumed either placebo or alcoholic drinks to attain a breath alcohol level of 0.10 during the evening before participation in Strategic Management Simulations. By the time of arrival at the simultaion laboratory on the following morning, breath alcohol levels were measured at 0.00. Questionnaire responses indicated considerable hangover discomfort. Responses to semantic differential evaluative scales suggested that research participants evaluated their own managerial performance in the simulation setting as impaired. However, multiple (validated) measures of decision-making performance obtained in the simulation task did not show any deterioration of functioning. Previous research had shown considerable performance decrements in the same task setting, while blood/breath alcohol levels ranged from 0.05 through 0.10%. Apparently, complex decision-making competence by persons who normally consume moderate amounts of alcohol may not be impaired by hangover caused by intoxication during the previous evening that remains at or below a blood alcohol level of 0.10.

Effects of caffeine deprivation on complex human functioning

Twenty-five managers who reported an average daily caffeine consumption of 575 mg participated in two complex simulations. A double-blind cross-over design was employed to assess the effects of normal caffeine consumption versus caffeine deprivation upon seven validated measures of managerial effectiveness. Data from a Caffeine Withdrawal Questionnaire indicated discomfort upon deprivation. Systolic blood pressure increased during "normal" caffeine consumption levels but fell quickly and remained lower during deprivation. Several measures of managerial performance indicated decreased effectiveness upon caffeine deprivation. In contrast to prior research from simpler task settings, cognitive effectiveness (during complex task performance) was diminished. However, a measure of strategic performance which requires a relatively high level of cognitive effort showed no impact of caffeine deprivation.

Alcohol and managerial performance

Effects of alcohol intoxication at .05 and .10 breath alcohol concentration upon a number of validated indicators of managerial performance were investigated in a double-blind crossover placebo-controlled simulation design. Managers (N = 48) spent 2 days handling quasi-experimental (partially event-controlled) tasks that permitted realistic managerial decision making under both "normal" and "emergency" conditions. The data showed that speed and frequency of managerial action were affected by alcohol at the .10 but not the .05 level. Strategy and planning deteriorated at both levels. Limited improvement of performance was observed for one simpler component of managerial functioning at the lower intoxication level, possibly due to myopia and/or a motivated "strain" toward better performance induced by the perception of impairment.

Effects of alcohol intoxication on risk taking, strategy, and error rate in visuomotor performance

Adult men (N = 44) participated for 2 days (alcohol vs. placebo treatment) in a double-blind, crossover experiment. Performance on the Digit Symbol Substitution Task (DSST) and a visuomotor (VM) task was measured 4 times each day. On the alcohol-treatment day, data were obtained once during ascending breath alcohol levels (BALs), once during maximal BALs (0.05 or 0.10), and twice during descending BALs. Data were collected at the same time points on the placebo-treatment day. Limited evidence for acute tolerance was obtained with the DSST, but error rates on the VM task were higher during maximal and descending BALs. Error rates remained near placebo values, and participants displayed slightly greater caution, while BALs were ascending. Strategy scores on the VM task exceeded placebo scores during maximal intoxication. Data interpretation is focused on individuals in higher level (e.g., professional) positions.

Linkage between cooperative oxygenation and subunit assembly of cobaltous human hemoglobin

The thermodynamic linkage between cooperative oxygenation and dimer-tetramer subunit assembly has been determined for cobaltous human hemoglobin in which iron(II) protoporphyrin IX is replaced by cobalt(II) protoporphyrin IX. The equilibrium parameters of the linkage system were determined by global nonlinear least-squares regression of oxygenation isotherms measured over a range of hemoglobin concentrations together with the deoxygenated dimer-tetramer assembly free energy determined independently from forward and reverse reaction rates. The total cooperative free energy of tetrameric cobalt hemoglobin (over all four binding steps) is found to be 1.84 (+/- 0.13) kcal, compared with the native ferrous hemoglobin value of 6.30 (+/- 0.14) kcal. Detailed investigation of stepwise cooperativity effects shows the following: (1) The largest change occurs at the first ligation step and is determined on model-independent grounds by knowledge of the intermediate subunit assembly free energies. (2) Cooperativity in the shape of the tetrameric isotherm occurs mainly during the middle two steps and is concomitant with the release of quaternary constraints. (3) Although evaluation of the pure tetrameric isotherm portrays identical binding affinity between the last two steps, this apparent noncooperativity is the result of a "hidden" oxygen affinity enhancement at the last step of 0.48 (+/- 0.12) kcal. This quaternary enhancement energy is revealed by the difference in subunit assembly free energies of the triply and fully ligated species and is manifested visually by the oxygenation isotherms at high versus low hemoglobin concentration. (4) Cobaltous hemoglobin dimers exhibit apparent anticooperativity of 0.49 (+/- 0.16) kcal (presumed to arise from heterogeneity of subunit affinities).(ABSTRACT TRUNCATED AT 250 WORDS)

Managing prostatitis in the elderly

Bacterial prostatitis is primarily a disease of elderly men, and it is the most common urinary tract infection seen in this age group. Urosepsis from prostatitis or prostatic abscess occurs less frequently than with urological manipulation, but must always be considered in elderly men with prostatitis. This article focuses on the diagnosis and antibiotic treatment of bacterial prostatitis in the elderly.

Pneumonia syndromes: a clinical approach in the elderly

Important in the pathogenesis of pneumonia in the elderly patient are chronic diseases, including diabetes mellitus, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, and cerebrovascular disease. Also vital are the changes that take place in the immune system and mucociliary clearance mechanisms of the lung. The clinician should be aware of these risk factors, especially since the mortality rate of lower respiratory infections approaches 40% in these elderly patients. Treatment guidelines are included.

Infections in the hospitalized elderly

Nosocomial infections are a particular problem among the elderly. Their cost is high mortality and a bill of $4 billion annually. The routine observation of a few simple aseptic practices will significantly blunt the impact of this health-care concern in our hospitals and nursing homes.

Three-state combinatorial switching in hemoglobin tetramers: comparison between functional energetics and molecular structures

In a previous study on cyanomethemoglobin the 10 tetrameric species (each with a unique combination of ligated and unligated subunits) were found to exhibit three distinct free energies of cooperative interaction. The distribution of these free energies among the partially ligated species is incompatible with a two-state mechanism of molecular switching and requires a minimum of three molecular structures with distinctly different free energies of heme-heme interaction. Ligand-linked transitions between the three cooperativity states were found to be "combinatorial"--i.e., dependent upon changes in both the number and specific configuration of bound ligands. Here we present results from two other chemical systems that mimic intermediate oxygenation states. In these systems the heme iron is replaced by manganese in certain of the subunits. We find the same distribution of cooperative free energies as reported for the cyanomethemoglobin system. These results demonstrate that the three-state combinatorial nature of cooperative switching is neither a special feature of the cyanomet reactions nor of the substitution of manganese for iron, but reflects a fundamental property of hemoglobin. These findings are compared with crystallographic structural results on partially ligated hemoglobins.

The binding of Gold(I) to metallothionein

The binding of gold(I) to metallothionein, MT, has been unambiguously established by the reaction of Na2AuTM with purified horse kidney MT. Zinc was displaced more readily than cadmium although the latter could be displaced using large Au/Cd ratios. The metal exchange reactions were complete within 2 hr of mixing. Further evidence that such reactions might be physiologically significant were obtained by studying in vitro metal displacements in the liver cytol of in vivo metal treated rats: When Na2AuTM was added to the cytosol of rats administered CdCl2 in vivo, zinc, copper and cadmium were displaced in 2/1/1 ratios from the metallothionein fraction. The zinc and cadmium displacement provide direct evidence that the gold was binding to MT. Addition of Cd+2 to liver cytosol of gold-treated rats resulted in displacement of copper and zinc, but not gold, from the MT fractions. When liver MT is prepared from rats exposed to Au or Cd, the Cd/protein ratio increased during the preparation, but the Au/protein ratio decreased. The Mt-bound metals account for 95% of the cytosolic Cd but only 15%-30% of the cytosolic gold in these studies. Thus, the nonspecific binding of gold to MT in vivo should be considered as one aspect in its equilibration among protein binding sites, which include, inter alia, metallothionein. Gold was found to coelute with zinc and cadmium in the MT fraction of rat kidney cytosol, when both Cd and Na2AuTM were administered to the rats. The possible significance of gold binding to MT in the treatment of rheumatoid arthritis--chrysotherapy--is briefly discussed.