Savi Scout Localization for Extrapelvic Endometriosis Resection

BACKGROUND Endometriosis is a common cause of chronic pelvic pain among women globally. Pharmacological therapy for endometriosis includes non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives, while surgical therapy often involves either laparoscopic excision and ablation of endometriosis implants or open surgery. Surgical therapy is one of the mainstays of treatment especially for extrapelvic endometriomas. However, little guidance exists for the treatment of non-palpable or intermittently palpable lesions of this nature. CASE REPORT A 33-year-old woman with a previous cesarean section presented with complaints of intermittent discomfort in the area between her umbilicus and the surgical incision, for the previous 7 years, that worsened during her menstrual cycle. A 3×3-cm area of fullness was only intermittently palpable during various clinic visits, but was visualizable on computed tomography and magnetic resonance imaging. Given the lesion's varying palpability, a Savi Scout radar localization device was placed into the lesion pre-operatively to aid with surgical resection. The mass was excised, pathologic examination revealed endometrial tissue, and the patient had an uncomplicated postoperative course with resolution of her symptoms. CONCLUSIONS Surgical removal of extrapelvic endometrioma lesions can be made difficult by varying levels of palpability or localizability due to a patient's menstrual cycle. The Savi Scout, most commonly used in breast mass localization, is a useful tool in guiding surgical excision of non-palpable or intermittently palpable extrapelvic endometrioma lesions.

Lung imaging patterns in connective tissue disease-associated interstitial lung disease impact prognosis and immunosuppression response

OBJECTIVES

Interstitial lung disease (ILD) in connective tissue diseases (CTD) have highly variable morphology. We aimed to identify imaging features and their impact on ILD progression, mortality and immunosuppression response.

METHODS

Patients with CTD-ILD had high-resolution chest computed tomography (HRCT) reviewed by expert radiologists blinded to clinical data for overall imaging pattern (usual interstitial pneumonia [UIP]; non-specific interstitial pneumonia [NSIP]; organizing pneumonia [OP]; fibrotic hypersensitivity pneumonitis [fHP]; and other). Transplant-free survival and change in percent-predicted forced vital capacity (FVC) were compared using Cox and linear mixed effects models adjusted for age, sex, smoking, and baseline FVC. FVC decline after immunosuppression was compared with pre-treatment.

RESULTS

Of 645 CTD-ILD patients, the frequent CTDs were systemic sclerosis (n = 215), rheumatoid arthritis (n = 127), and inflammatory myopathies (n = 100). NSIP was the most common pattern (54%), followed by UIP (20%), fHP (9%), and OP (5%). Compared with UIP, FVC decline was slower for NSIP (1.1%/year, 95%CI 0.2, 1.9) and OP (3.5%/year, 95%CI 2.0, 4.9), and mortality was lower for NSIP (HR 0.65, 95%CI 0.45, 0.93) and OP (HR 0.18, 95%CI 0.05, 0.57), but higher in fHP (HR 1.58, 95%CI 1.01, 2.40). The extent of fibrosis also predicted FVC decline and mortality. After immunosuppression, FVC decline was slower compared with pre-treatment in NSIP (by 2.1%/year, 95%CI 1.4, 2.8), with no change for UIP or fHP.

CONCLUSION

Multiple radiologic patterns are possible in CTD-ILD, including a fHP pattern. NSIP and OP were associated with better outcomes and response to immunosuppression, while fHP had worse survival compared with UIP.

Integration and Application of Radiologic Patterns From Clinical Practice Guidelines on Idiopathic Pulmonary Fibrosis and Fibrotic Hypersensitivity Pneumonitis

BACKGROUND

Clinical practice guidelines separately describe radiologic patterns of usual interstitial pneumonia (UIP) and fibrotic hypersensitivity pneumonitis (fHP), without direction on whether or how to apply these approaches concurrently within a single patient.

RESEARCH QUESTION

How can we integrate guideline-defined radiologic patterns to diagnose interstitial lung disease (ILD) and what are the pitfalls associated with described patterns that require reassessment in future guidelines?

STUDY DESIGN AND METHODS

Patients from the Canadian Registry for Pulmonary Fibrosis underwent detailed reevaluation in standardized multidisciplinary discussion. CT scan features were quantified by chest radiologists masked to clinical data, and guideline-defined patterns were assigned. Clinical data then were provided to the radiologist and an ILD clinician, who jointly determined the leading diagnosis.

RESULTS

Clinical-radiologic diagnosis in 1,593 patients was idiopathic pulmonary fibrosis (IPF) in 26%, fHP in 12%, connective tissue disease-associated ILD (CTD-ILD) in 34%, idiopathic pneumonia with autoimmune features in 12%, and unclassifiable ILD in 10%. Typical and probable UIP patterns corresponded to a diagnosis of IPF in 66% and 57% of patients, respectively. Typical fHP pattern corresponded to an fHP clinical diagnosis in 65% of patients, whereas compatible fHP was nonspecific and associated with CTD-ILD or IPAF in 48% of patients. No pattern ruled out CTD-ILD. Gas trapping affecting > 5% of lung parenchyma on expiratory imaging was an important feature broadly separating compatible and typical fHP from other patterns (sensitivity, 0.77; specificity, 0.91).

INTERPRETATION

An integrated approach to guideline-defined UIP and fHP patterns is feasible and supports > 5% gas trapping as an important branch point. Typical or probable UIP and typical fHP patterns have moderate predictive values for a corresponding diagnosis of IPF and fHP, although occasionally confounded by CTD-ILD; compatible fHP is nonspecific.

Perceived Neighborhood Racial Composition and Depressive Symptoms Among Black Americans Across Adulthood: Evaluating the Role of Psychosocial Risks and Resources

Objectives: To evaluate the relationships between perceived neighborhood racial composition (PNRC), psychosocial risks and resources, and depressive symptoms among young (ages 22-35), middle-aged (ages 36-49), and older (ages 50+) Black Americans. Methods: Full sample and age-stratified linear regression models estimated the PNRC-depressive symptoms association and the extent to which it persisted after accounting for psychosocial risks (i.e., neighborhood disorder, other social stressors) and resources (i.e., mastery, social support, racial identity) among 627 Black Americans in the Nashville Stress and Health Study. Results: Living in racially integrated and predominately White neighborhoods was associated with elevated depressive symptoms. While psychosocial risks and resources explained a substantial portion of these associations, patterns varied across age groups. Discussion: PNRC impacts depressive symptoms among Black Americans by shaping psychosocial risks and resources. Findings underscore interconnections between contextual and psychosocial factors, as well as the distinct mental health significance of these processes across stages of adulthood.

"Family Is the Beginning but Not the End": Intergenerational LGBTQ Chosen Family, Social Support, and Health in a Vietnamese American Community Organization

Homophobia and anti-LGBTQ (Lesbian, Gay, Bisexual, Transgender, and Queer) discrimination within ethnic communities can negatively impact the health of LGBTQ people. The formation of chosen families has been a source of social support that may have health benefits for LGBTQ people. This ethnographic study explores how participation in a LGBTQ Vietnamese American community organization reveals the salience of chosen family in informing individual members' perceptions of their health and well-being. Fifteen members were interviewed and over 30 were included in a 6-month participant-observation period. Three themes emerged: 1) queering family and kinship, 2) Vietnamese motherhood and the social reproduction of the family, 3) social ties and community connectedness as relational dimensions of health. Findings suggest that specific ethnic social support via chosen family formations for LGBTQ Vietnamese Americans can shape individuals' sense of self, sense of belonging, purpose in life, and consequently perceptions of well-being.

A Rare Case of Ruptured Appendicitis Secondary to Metastatic Ovarian Cancer

BACKGROUND Patients with advanced stage ovarian cancer typically have vague non-specific abdominal symptoms related to pelvic tumor, metastasis, and ascites. When these patients present with more acute abdominal pain, appendicitis is rarely considered. Acute appendicitis due to metastatic ovarian cancer has been sparsely documented in the medical literature; only twice, to our knowledge. CASE REPORT A 61-year-old woman with a 3-week history of abdominal pain, shortness of breath, and bloating was diagnosed with ovarian cancer after computed tomography (CT) demonstrated a large pelvic cystic and solid mass. Five weeks later she underwent an omental biopsy to determine cell type and potential upstaging of the ovarian cancer to stage IV, as other aggressive cancers such as breast cancer can also involve the pelvis/omentum. Seven hours after her biopsy, she presented with increasing abdominal pain. Post-biopsy complications such as hemorrhage or bowel perforation were initially suspected to be the cause of her abdominal pain. However, CT demonstrated ruptured appendicitis. The patient underwent an appendectomy and histopathologic examination of the specimen revealed infiltration by low-grade ovarian serous carcinoma. CONCLUSIONS Given the low incidence of spontaneous acute appendicitis in this patient's age group, and the lack of any other clinical, surgical, or histopathological evidence to suggest another cause, metastatic disease was ruled to be the likely source of her acute appendicitis. Providers should be aware of appendicitis in a broad differential diagnosis and have a low threshold for ordering abdominal pelvis CT when advanced stage ovarian cancer patients present with acute abdominal pain.

The mental health of Asian American adolescents and young adults amid the rise of anti-Asian racism

Objectives

We describe the perceptions and experiences of anti-Asian racism and violence and depression severity prior to and during the COVID-19 pandemic among a sample of Asian American (AA) adolescents and young adults.

Methods

We used data from the Young Asian American Health Survey (YAAHS), an online-recruited sample of AA adolescents (ages 13-17) and young adults (ages 18-29 years) conducted during May 2021 to March 2022. We presented descriptive statistics examining the univariate distribution and bivariate relationships of depression severity, sociodemographic characteristics, and experiences and perceptions of anti-Asian violence.

Results

Our sample (n = 176) comprised AA adolescents and young adults from 17 Asian ethnicities. A quarter said that the frequency and/or severity of their personal experiences of anti-Asian harassment had increased since the pandemic started. 76% indicated feeling less safe now than before the pandemic. Two-thirds reported that their depressive symptoms have increased since the pandemic started. Participants who reported feeling less safe now than before the pandemic were more likely to report increased personal experiences with anti-Asian harassment and increased depression severity since the pandemic started than those who reported feeling as safe or safer before the pandemic (p < 0.01 for both).

Discussion

Findings illustrate AA adolescent and young adults are experiencing multiple health and social crises stemming from increased anti-Asian racism during the COVID-19 pandemic. We urge policymakers to strengthen data systems that connect racial discrimination and mental health and to institute prevention measures and anti-racist mental health services that are age- and culturally-appropriate for AA adolescent and young adults.

Exosomal-ribosomal proteins-driven heterogeneity of epicardial adipose tissue derived stem cells under ischemia for cardiac regeneration

Extracellular ribosomal proteins secreted in exosomes elicit biological/regenerative responses; however, ribosomal proteins contained in the exosomes of ischemia-challenged epicardial adipose tissue-derived stem cells (EATDS) remain unexplored. This study focuses on the identification of ribosomal proteins in the exosomes of ischemia-challenged EATDS and their sub-populations based on the key ribosomal proteins using single-cell genomics. Exosomes were isolated from control, ischemic (ISC), and reperfused (ISC/R) EATDS harvested from hyperlipidemic microswine, and the proteins were detected using Liquid chromatography with tandem mass spectrometry (LC-MS/MS). One hundred ninety-nine proteins and 177 proteins were detected in ISC and ISC/R groups, respectively with significant fold-change compared to controls. Five ribosomal proteins, RPL10A, 40SRPS18, 40SRPS30, 60SRPL14, and 40SRPSA, were significant owing to their abundance based on LC-MS/MS data. Expression of these proteins, except RPL10A, at transcript and protein levels were lower in ISC group compared to the control. scRNAseq analysis revealed EATDS heterogeneity based on the upregulation of 40SRPSA, 40SRPL18, and 40SRPS18. Pro-inflammatory sub-populations upregulated CCL5, anti-inflammatory sub-population upregulated IL-11, proliferative sub-population upregulated cell cycle and DNA replication mediators, and non-proliferative population downregulated the cell cycle and DNA replication mediators. Overall, the functional role of extracellular ribosomal proteins in driving unique phenotypes of EATDS population offers promise for designing effective translational approaches for myocardial regeneration.

Is Call Karma Real? Resident After-Hours On-Call Imaging at the University of Saskatchewan: An Assessment of Call Volumes Including Inter-Resident Variability

PURPOSE

Quantify resident caseload during call and determine if there are consistent differences in call volumes for individuals or resident subgroups.

METHODS

Accession codes for after-hours computed tomography (CT) cases dictated by residents between July 1, 2012 and January 9, 2017 were reviewed. Case volumes by patient visits and body regions scanned were determined and categorized according to time period, year, and individual resident. Mean shift Relative Value Units (RVUs) were calculated by year. Descriptive statistics, linear mixed modeling, and linear regression determined mean values, differences between residents, associations between independent variables and outcomes, and changes over time. Consistent differences between residents were assessed as a measure of good or bad luck / karma on call.

RESULTS

During this time there were 23,032 patients and 30,766 anatomic regions scanned during 1,652 call shifts among 32 residents. Over the whole period, there were on average 10.6 patients and 14.3 body regions scanned on weekday shifts and 22.3 patients and 29.4 body regions scanned during weekend shifts. Annually, the mean number of patients, body regions, and RVUs scanned per shift increased by an average of 0.2 (1%), 0.4 (2%), and 1.2 (5%) (all p < 0.05) respectively in regression models. There was variability in call experiences, but only 1 resident had a disproportionate number of higher volume calls and fewer lower volume shifts than expected.

CONCLUSIONS

Annual increases in scan volumes were modest. Although residents' experiences varied, little of this was attributable to consistent personal differences, including luck or call karma.

Synchronizing single-shot high-energy iodine photodissociation laser PALS and high-repetition-rate femtosecond Ti:sapphire laser system

A system of precise pulse synchronization between a single-shot large-scale laser exploiting an acousto-optical modulator and a femtosecond high repetition rate laser is reported in this article. This opto-electronical system has been developed for synchronization of the sub-nanosecond kJ-class iodine photodissociation laser system (Prague Asterix Laser System-PALS) with the femtosecond 25-TW Ti:sapphire (Ti:Sa) laser operating at a repetition rate 1 kHz or 10 Hz depending on the required energy level of output pulses. At 1 kHz synchronization regime, a single femtosecond pulse of duration about 45 fs and a small energy less than 1 mJ are exploited as a probe beam for irradiation of a three-frame interferometer, while at 10 Hz repetition rate a single femtosecond pulse with higher energy about 7-10 mJ is exploited as a probe beam for irradiation of a two-channel polaro-interferometer. The synchronization accuracy ±100 ps between the PALS and the Ti:Sa laser pulses has been achieved in both regimes of synchronization. The femtosecond interferograms of laser-produced plasmas obtained by the three-frame interferometer and the femtosecond polarimetric images obtained by the two-frame polaro-interferometer confirm the full usefulness and correct functionality of the proposed method of synchronization.

Abstract P5-10-03: XRAYS (eXamining Relevance of Articles to Young Survivors) program survey of information needs and media use by young breast cancer survivors and young women at high risk for breast cancer

Women age 45 or under with breast cancer, or who are at high risk for breast cancer, have distinct health risks and needs when compared to their older counterparts. Young women with breast cancer or at high risk for breast cancer need evidence-based, high-quality information to help them make informed decisions about their specific health needs. Interpreting media reports on research findings, including determining the study implications for younger women is often challenging. To help women better understand media coverage of new research, Facing Our Risk of Cancer Empowered (FORCE) developed the CDC-funded XRAYS (eXamining Relevance of Articles to Young Survivors) program. To assure that the XRAYS program is responsive to the community's needs, FORCE launched a survey to assess where young women turn for information about breast cancer and to identify their information needs. The survey examines: how frequently women visit various media sources and health- or cancer-related websites for information on breast cancer screening, treatment, surgery, prevention, genetics, or survivorship; how much the women trust these information sources; whether they have ever tried to share media articles with their health care team and how the team received the information; and at what point(s) during the process of screening, diagnosis, treatment, survivorship and/or risk management respondents actively seek out information from the media. FORCE launched the survey nationally through its network of 50 outreach groups, partner organizations that serve young breast cancer survivors, and via a social media campaign targeting women age 45 and under with, or at high risk for breast cancer. The survey was open March 15 - June 30, 2015. We will report results from over 800 women, age 45 or younger, including those with breast cancer, who have previously had breast cancer, or who are at high risk for breast cancer. Analysis will determine response frequencies and whether information needs and utilization correlate with key demographic variables such as race/ethnicity, education, and income level. We will use correlation and multiple regression analysis to assess patterns in the types of information needed and channels where information is sought. These results will ensure XRAYS materials and dissemination efforts are efficient and responsive to the young breast cancer population's needs, and will inform the broader medical, media and patient advocacy communities about the distinct information needs of this group.

Citation Format: Rezende LF, Huynh J, Kramer K, Cranmer M, Schlager L, Pugh-Yi R, Friedman S. XRAYS (eXamining Relevance of Articles to Young Survivors) program survey of information needs and media use by young breast cancer survivors and young women at high risk for breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-10-03.

Impact of HIV-1 Membrane Cholesterol on Cell-Independent Lytic Inactivation and Cellular Infectivity

Peptide triazole thiols (PTTs) have been found previously to bind to HIV-1 Env spike gp120 and cause irreversible virus inactivation by shedding gp120 and lytically releasing luminal capsid protein p24. Since the virions remain visually intact, lysis appears to occur via limited membrane destabilization. To better understand the PTT-triggered membrane transformation involved, we investigated the role of envelope cholesterol on p24 release by measuring the effect of cholesterol depletion using methyl beta-cyclodextrin (MβCD). An unexpected bell-shaped response of PTT-induced lysis to [MβCD] was observed, involving lysis enhancement at low [MβCD] vs loss of function at high [MβCD]. The impact of cholesterol depletion on PTT-induced lysis was reversed by adding exogenous cholesterol and other sterols that support membrane rafts, while sterols that do not support rafts induced only limited reversal. Cholesterol depletion appears to cause a reduced energy barrier to lysis as judged by decreased temperature dependence with MβCD. Enhancement/replenishment responses to [MβCD] also were observed for HIV-1 infectivity, consistent with a similar energy barrier effect in the membrane transformation of virus cell fusion. Overall, the results argue that cholesterol in the HIV-1 envelope is important for balancing virus stability and membrane transformation, and that partial depletion, while increasing infectivity, also makes the virus more fragile. The results also reinforce the argument that the lytic inactivation and infectivity processes are mechanistically related and that membrane transformations occurring during lysis can provide an experimental window to investigate membrane and protein factors important for HIV-1 cell entry.

Activation of μ opioid receptors modulates inflammation in acute experimental colitis

BACKGROUND

μ opioid receptors (μORs) are expressed by neurons and inflammatory cells, and mediate immune response. We tested whether activation of peripheral μORs ameliorates the acute and delayed phase of colitis.

METHODS

C57BL/6J mice were treated with 3% dextran sodium sulfate (DSS) in water, 5 days with or without the peripherally acting μOR agonist, [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin (DAMGO) or with DAMGO+μOR antagonist at day 2-5, then euthanized. Other mice received DSS followed by water for 4 weeks, or DSS with DAMGO starting at day 2 of DSS for 2 or 3 weeks followed by water, then euthanized at 4 weeks. Disease activity index (DAI), histological damage, and myeloperoxidase assay (MPO), as index of neutrophil infiltration, were evaluated. Cytokines and μOR mRNAs were measured with RT-PCR, and nuclear factor-kB (NF-kB), the antiapoptotic factor Bcl-xL, and caspase 3 and 7 with Western blot.

KEY RESULTS

DSS induced acute colitis with elevated DAI, tissue damage, apoptosis and increased MPO, cytokines, μOR mRNA, and NF-kB. DAMGO significantly reduced DAI, inflammatory indexes, cytokines, caspases, and NF-kB, and upregulated Bcl-xL, effects prevented by μOR antagonist. In DSS mice plus 4 weeks of water, DAI, NF-kB, and μOR were normal, whereas MPO, histological damage, and cytokines were still elevated; DAMGO did not reduce inflammation, and did not upregulate Bcl-xL.

CONCLUSIONS & INFERENCES

μOR activation ameliorated the acute but not the delayed phase of DSS colitis by reducing cytokines, likely through activation of the antiapoptotic factor, Bcl-xL, and suppression of NF-kB, a potentiator of inflammation.

History of chronic comorbidity and risk of chemotherapy-induced febrile neutropenia in cancer patients not receiving G-CSF prophylaxis

BACKGROUND

Chemotherapy-induced febrile neutropenia (FN) is a clinically important complication that affects patient outcome by delaying chemotherapy doses or reducing dose intensity. Risk of FN depends on chemotherapy- and patient-level factors. We sought to determine the effects of chronic comorbidities on risk of FN.

DESIGN

We conducted a cohort study to examine the association between a variety of chronic comorbidities and risk of FN in patients diagnosed with six types of cancer (non-Hodgkin lymphoma and breast, colorectal, lung, ovary, and gastric cancer) from 2000 to 2009 who were treated with chemotherapy at Kaiser Permanente Southern California, a large managed care organization. We excluded those patients who received primary prophylactic granulocyte colony-stimulating factor. History of comorbidities and FN events were identified using electronic medical records. Cox models adjusting for propensity score, stratified by cancer type, were used to determine the association between comorbid conditions and FN. Models that additionally adjusted for cancer stage, baseline neutrophil count, chemotherapy regimen, and dose reduction were also evaluated.

RESULTS

A total of 19 160 patients with mean age of 60 years were included; 963 (5.0%) developed FN in the first chemotherapy cycle. Chronic obstructive pulmonary disease [hazard ratio (HR) = 1.30 (1.07-1.57)], congestive heart failure [HR = 1.43 (1.00-1.98)], HIV infection [HR = 3.40 (1.90-5.63)], autoimmune disease [HR = 2.01 (1.10-3.33)], peptic ulcer disease [HR = 1.57 (1.05-2.26)], renal disease [HR = 1.60 (1.21-2.09)], and thyroid disorder [HR = 1.32 (1.06-1.64)] were all associated with a significantly increased FN risk.

CONCLUSIONS

These results provide evidence that history of several chronic comorbidities increases risk of FN, which should be considered when managing patients during chemotherapy.

Prevalence of gestational diabetes mellitus among Swampy Cree women in Moose Factory, James Bay

BACKGROUND

Although high rates of gestational diabetes mellitus have been documented in native populations, few studies have examined rates of the disease among native Indians in Canada. The authors conducted a study to estimate the prevalence of gestational diabetes among Swampy Cree women, to identify factors predictive of the occurrence of gestational diabetes, and to identify delivery and infant outcomes related to the presence of the disease.

METHODS

Information on Swampy Cree women who gave birth at Weeneebayko Hospital, Moose Factory, James Bay, Ont., between 1987 and 1995 was obtained from medical charts. Patients with and without gestational diabetes were compared. Logistic regression analysis was used to identify independent predictors of gestational diabetes. Delivery and infant outcomes that occurred secondary to gestational diabetes were also identified by means of logistic regression.

RESULTS

A total of 1401 deliveries occurred at Weeneebayko Hospital over the study period, of which 1298 were included in the study. Gestational diabetes was diagnosed in 110 (8.5% [95% confidence interval (CI) 6.9%-9.9%]) of the 1298 pregnancies. Factors predictive of gestational diabetes were age 35 years or more (relative risk [RR] 4.1, 95% CI 1.5-11.7), a history of gestational diabetes in a previous pregnancy (RR 6.4, 95% CI 3.5-11.7), diastolic blood pressure of 80 mm Hg or higher at the first prenatal visit (RR 1.7, 95% CI 1.1-2.8), weight greater than 80 kg at the first prenatal visit (RR 4.9, 95% CI 1.8-12.9) and having a first-degree relative with diabetes (RR 3.0, 95% CI 1.4-6.1). The only delivery outcome independently associated with the presence of gestational diabetes was an increased likelihood of needing assisted delivery (forceps or vacuum extraction) (RR 2.8, 95% CI 1.1-7.0). Shoulder dystocia was indirectly associated with gestational diabetes owing to increased infant birth weight. Infant outcomes associated with the presence of gestational diabetes were birth weight greater than 4500 g (RR 2.4, 95% CI 1.4-3.8), hyperbilirubinemia (RR 2.9, 95% CI 1.4-6.1), hypoglycemia (RR 7.3, 95% CI 3.7-14.4) and hypocalcemia (RR 8.9, 95% CI 2.3-33.7).

INTERPRETATION

Gestational diabetes occurred in a significant minority of Swampy Cree women and was associated with a number of adverse outcomes.

The role of the non-conserved residue at position 104 of class A beta-lactamases in susceptibility to mechanism-based inhibitors

The role of the non-conserved amino acid residue at position 104 of the class A beta-lactamases, which comprises a highly conserved sequence of amino acids at the active sites of these enzymes, in both the hydrolysis of beta-lactam substrates and inactivation by mechanism-based inhibitors was investigated. Site-directed mutagenesis was performed on the penPC gene encoding the Bacillus cereus 569/H beta-lactamase I to replace Asp104 with the corresponding Staphylococcus aureus PC1 residue Ala104. Kinetic data obtained with the purified Asp104Ala B. cereus 569/H beta-lactamase I was compared to that obtained from the wild-type B. cereus and S. aureus enzymes. Replacement of amino acid residue 104 had little effect on the Michaelis parameters for the hydrolysis of both S- and A-type penicillins. Relative to wild-type enzyme, the Asp104Ala beta-lactamase I had 2-fold higher Km values for benzylpenicillin and methicillin, but negligible difference in Km for ampicillin and oxacillin. However, kcat values were also slightly increased resulting in little change in catalytic efficiency, kcat/Km. In contrast, the Asp104Ala beta-lactamase I became more like the S. aureus enzyme in its response to the mechanism-based inhibitors clavulanic acid and 6-beta-(trifluoromethane sulfonyl)amido-penicillanic acid sulfone with respect to both response to the inhibitors and subsequent enzymatic properties. Based on the known three-dimensional structures of the Bacillus licheniformis 749/C, Escherichia coli TEM and S. aureus PC1 beta-lactamases, a model for the role of the non-conserved residue at position 104 in the process of inactivation by mechanism-based inhibitors is proposed.