Re-Envisioning the Culture of Undergraduate Biology Education to Foster Black Student Success: A Clarion Call.

The purpose of this paper is to present an argument for why there is a need to re-envision the underlying culture of undergraduate biology education to ensure the success, retention, and matriculation of Black students. The basis of this argument is the continued noted challenges with retaining Black students in the biological sciences coupled with existing research that implicates science contexts (i.e., the cultural norms, values, and beliefs manifesting through policies and practices) as being the primary source of the challenges experienced by Black students that lead to their attrition. In presenting this argument, we introduce the Re-Envisioning Culture Network, a multigenerational, interdisciplinary network comprised of higher education administrators, faculty, staff, Black undergraduate students majoring in biology, Black cultural artists, community leaders, and STEM professionals to work together to curate and generate resources and tools that will facilitate change. In introducing the REC Network and disseminating its mission and ongoing endeavors, we generate a clarion call for educators, researchers, STEM professionals, students, and the broader community to join us in this endeavor in fostering transformative change.

Magnetic resonance imaging T1 indices of the brain as biomarkers of inhaled manganese exposure.

Excessive exposure to manganese (Mn) is linked to its accumulation in the brain and adverse neurological effects. Paramagnetic properties of Mn allow the use of magnetic resonance imaging (MRI) techniques to identify it in biological tissues. A critical review was conducted to evaluate whether MRI techniques could be used as a diagnostic tool to detect brain Mn accumulation as a quantitative biomarker of inhaled exposure. A comprehensive search was conducted in MEDLINE, EMBASE, and PubMed to identify potentially relevant studies published prior to 9 May 2022. Two reviewers independently screened identified references using a two-stage process. Of the 6452 unique references identified, 36 articles were retained for data abstraction. Eligible studies used T1-weighted MRI techniques and reported direct or indirect T1 measures to characterize Mn accumulation in the brain. Findings demonstrate that, in subjects exposed to high levels of Mn, deposition in the brain is widespread, accumulating both within and outside the basal ganglia. Available evidence indicates that T1 MRI techniques can be used to distinguish Mn-exposed individuals from unexposed. Additionally, T1 MRI may be useful for semi-quantitative evaluation of inhaled Mn exposure, particularly when interpreted along with other exposure indices. T1 MRI measures appear to have a nonlinear relationship to Mn exposure duration, with R1 signal only increasing after critical thresholds. The strength of the association varied depending on the regions of interest imaged and the method of exposure measurement. Overall, available evidence suggests potential for future clinical and risk assessment applications of MRI as a diagnostic tool.

Biomarkers for occupational manganese exposure.

Long-term inhalation exposure to manganese (Mn) metal or its inorganic compounds can result in manganism or subclinical neurofunctional deficits. Studies have described affected workers in Mn dioxide mining, Mn-containing ore crushing and milling facilities, manufacturing of dry-cell batteries, Mn steel and alloy production plants, and in welders. The objective of this study was to critically review existing evidence on the reliability of potential biomarkers of Mn exposure, specifically the relationship between inhalation exposure to Mn particulates in different occupational settings and Mn concentrations in blood and other biological fluids and tissues, with a particular focus on whole blood as a potentially useful medium for measuring internal tissue dose. We also examined available evidence on the relationship between Mn levels in blood and adverse clinical and subclinical neurotoxic outcomes. Three bibliographic databases were searched for relevant studies and identified references were screened by two independent reviewers. Of the 6338 unique references identified, 76 articles were retained for data abstraction. Findings indicate that the relationships between Mn in blood and both external Mn exposure indices and neurofunctional impairments are limited and inconsistent. Different sources of exposure to Mn compounds, heterogeneity in the methodological approaches, and inadequate reporting of essential information limited direct comparison of the reported findings. Among the Mn-exposure biomarkers considered in this review - including biomarkers in blood, plasma, serum, erythrocytes, urine, bone, toenails, fingernails, hair, saliva - biomarkers in whole blood may provide to be most useful in Mn biomonitoring and risk assessment.

Nitrotyrosine, inducible nitric oxide synthase (iNOS), and endothelial nitric oxide synthase (eNOS) are increased in thyroid tumors from children and adolescents.

Nitric oxide (NO) is a reactive cell signal that controls vascular tone and is generated by inducible (iNOS), endothelial (eNOS) and neuronal (nNOS) NO synthase (NOS). We hypothesized that NO could be important for growth of thyroid tumors and tested this hypothesis, by staining 41 papillary thyroid carcinoma (PTC), 9 follicular thyroid carcinoma (FTC), and 15 benign thyroid lesions for iNOS, eNOS and nitrotyrosine (N-TYR). Staining intensity was determined by 2 blinded, independent examiners, and quantified from grade 1 (absent) to grade 4 (intense). Average N-TYR staining of benign adenomas (2.5+/-0.42, p=0.009), PTC (3.10+/-0.12, p=0.001), FTC (2.44+/-0.30, p=0.001), and autoimmune lesions (3.25+/-0.48, p=0.019) were greater than that of multinodular goiter (1.0 for all 3) and surrounding normal thyroid (1.1+/-0.1). Average iNOS staining of benign adenomas (2.6+/-0.37), PTC (2.7+/-0.16), FTC (2.4+/-0.26) and autoimmune lesions (3.5+/-0.29) were all greater than that of surrounding normal thyroid (1.1+/-0.1, p<0.008), but there were too few multinodular goiters to achieve a significant difference (no.=2, 3.0+/-1.0). Average eNOS staining of benign adenomas (2.9+/-0.40), multinodular goiters (3.5+/-0.5), PTC (3.24+/-0.18), FTC (3.5+/-0.50), and autoimmune lesions (2.8+/-0.6) were also greater than that of surrounding normal thyroid (mean=1.4+/-0.2, p<0.001). N-TYR staining correlated with that of vascular endothelial growth factor (VEGF, r=0.36, p=0.007) and the number of lymphocytes/high power field (r=0.39, p=0.004). Recurrent disease developed only from carcinoma with moderate-intense N-TYR staining, but there were too few recurrent tumors to achieve statistical significance (p=0.08). We conclude that NO is produced by benign adenomas, PTC and FTC suggesting that NO could be important in vascularization of thyroid tumors and autoimmune thyroid diseases.

A primary culture of guinea pig gallbladder epithelial cells that is responsive to secretagogues.

We have developed a cell culture of guinea pig gallbladder epithelial cells with which to study ion transport. When grown on permeable supports, the cultured epithelia developed a transepithelial resistance (R(t)) of approximately 500 Omega. cm(2). The epithelial cell origin of the cell culture was further confirmed by immunocytochemical localization of cytokeratin. Ionomycin and forskolin increased transepithelial voltage and short-circuit current (I(sc)) and decreased R(t). The response to ionomycin was transient, whereas that to forskolin was sustained. Both were attenuated by replacement of Cl(-) and/or HCO(3)(-). Mucosal addition of the anion transport inhibitors DIDS or diphenylamine-2-carboxylic acid (DPC) blocked the response to ionomycin. The response to forskolin was blocked by DPC but not by DIDS. Ionomycin, but not forskolin, increased intracellular Ca(2+) concentration in fura 2-loaded cells. PGE(2), histamine, vasoactive intestinal polypeptide, and secretin elicited a sustained increase in I(sc). Responses to ATP and CCK were transient. Thus cultured guinea pig gallbladder epithelia display the range of responses observed in the native tissue and are an appropriate model for studies of ion transport in gallbladder and intestinal epithelia.

Rat strain minimally influences anesthetic and convulsant requirements of inhaled compounds in rats.

UNLABELLED: We assessed the effect of rat strain on susceptibility to anesthesia and convulsions produced by inhaled compounds. We determined the minimum alveolar anesthetic concentration (MAC) of desflurane and nitrous oxide, and the convulsive 50% effective dose (ED50) of 1,2-dichlorohexafluorocyclobutane, flurothyl, and difluoromethyl-1-chlorotetrafluoroethyl ether in five strains (three inbred [Long Evans, Sprague-Dawley, and Wistar] and two outbred [Fischer and Brown Norway]). Strain had slight effects on anesthetic potency, the strains with the highest MAC values (Long Evans and Brown Norway) having values < or =28% greater than the strains with the lowest values (Sprague Dawley and Wistar). MAC for nitrous oxide correlated directly with MAC for desflurane as a function of strain. MAC for either desflurane or nitrous oxide correlated inversely with the convulsive ED50 of 1,2-dichlorohexafluorocyclobutane, but correlated poorly (and directly) with the convulsive ED50 of the remaining compounds. Convulsivity varied little as a function of strain (greatest difference 21%) and did not vary consistently as a function of strain. No consistent difference was seen between inbred versus outbred strains. IMPLICATIONS: Rat strain has a minimal effect on the potency of inhaled anesthetics or the convulsant activity of inhaled compounds. It seems that the sites acted on by inhaled compounds to produce anesthesia and convulsions are conserved across common rat strains.

Hip and knee replacement as a relative contraindication to laparoscopic pelvic lymph node dissection.

PURPOSE: We investigated the effect of lower extremity joint prostheses on subsequent laparoscopic pelvic lymph node dissection. MATERIALS AND METHODS: We reviewed the records and pathology studies of 5 patients who underwent laparoscopic pelvic lymph node dissection subsequent to total hip or knee replacement from 1990 through 1995. RESULTS: Four of the 5 laparoscopic operations were complicated, 3 were unsuccessful in obtaining bilateral pelvic lymph nodes and 2 required conversion to an open procedure. Examination of the lymph nodes revealed sinus histiocytosis in the 4 cases in which nodal tissue was removed. CONCLUSIONS: The increased risk of complications in certain patients with lower extremity joint prostheses may contraindicate attempted laparoscopic pelvic lymph node dissection.

Focal microsatellite mutations in relatives with prostatic adenocarcinoma.

Instability of short tandem repeat sequences, microsatellite instability (MI), has been reported to play an important role in the tumorigenesis of various adenocarcinomas, including prostatic adenocarcinoma. Although prostate cancer is not widely recognized as a heriditary cancer, familial clustering is well known. To investigate the frequency of microsatellite instability in familial prostatic adenocarcinomas we analyzed archival tumor tissue from seven paired first degree relatives with prostatic adenocarcinoma. Twelve dinucleotide, nine trinucleotide, six tetranucleotide repeats and the CAG repeat of the androgen receptor gene were screened for MI. Solitary mutations were observed in four separate cases (28.6%) and widespread somatic alterations were not identified. No statistical correlation to pathological characteristics was determined. Our data indicate that microsatellite instability is an uncommon phenomenon in prostatic adenocarcinoma within first degree relatives. Those changes present appear to manifest as focal mutations in contrast to the more global changes seen in MI.

Peptides containing a consensus Ras binding sequence from Raf-1 and theGTPase activating protein NF1 inhibit Ras function.

A key event in Ras-mediated signal transduction and transformation involves Ras interaction with its downstream effector targets. Although substantial evidence has established that the Raf-1 serine/threonine kinase is a critical effector of Ras function, there is increasing evidence that Ras function is mediated through interaction with multiple effectors to trigger Raf-independent signaling pathways. In addition to the two Ras GTPase activating proteins (GAPs; p120- and NF1-GAP), other candidate effectors include activators of the Ras-related Ral proteins (RalGDS and RGL) and phosphatidylinositol 3-kinase. Interaction between Ras and its effectors requires an intact Ras effector domain and involves preferential recognition of active Ras-GTP. Surprisingly, these functionally diverse effectors lack significant sequence homology and no consensus Ras binding sequence has been described. We have now identified a consensus Ras binding sequence shared among a subset of Ras effectors. We have also shown that peptides containing this sequence from Raf-1 (RKTFLKLA) and NF1-GAP (RRFFLDIA) block NF1-GAP stimulation of Ras GTPase activity and Ras-mediated activation of mitogen-activated protein kinases. In summary, the identification of a consensus Ras-GTP binding sequence establishes a structural basis for the ability of diverse effector proteins to interact with Ras-GTP. Furthermore, our demonstration that peptides that contain Ras-GTP binding sequences can block Ras function provides a step toward the development of anti-Ras agents.

Histopathological features and p53 nuclear protein staining as predictors of survival and tumor recurrence in patients with transitional cell carcinoma of the renal pelvis.

PURPOSE: We determine which histopathological features are predictive of recurrence and cause-specific survival in renal pelvic transitional cell carcinoma. MATERIALS AND METHODS: Univariant and multivariant analysis was done on material from 67 patients. RESULTS: Univariate and multivariate analysis identified lamina propria invasion, grade 3 tumors and capillary-lymphatic invasion as predictors of disease-specific survival. Multicentric disease was the sole independent predictor of recurrence. Multicentric disease and lamina propria invasion were independent predictors of recurrence-free survival. Also, p53 over-expression was not statistically associated with any of the studied prognostic factors. CONCLUSIONS: Histopathological features remain the cornerstone of prognostic assessment for renal pelvic transitional cell carcinoma.

Microsatellite instability in adenocarcinoma of the prostate.

Instability of dinucleotide tandem repeat sequences has been reported to play a major role in the carcinogenic pathway of familial colon cancer, as well as a potential role in the carcinogenesis of other sporadic neoplasms. To determine the frequency of short tandem repeat instability in adenocarcinoma of the prostate, we studied 40 tumors that were stratified according to tumor grade. The tissue samples were screened with di-, tri- and tetranucleotide markers spanning a wide range of chromosomal loci, including an androgen receptor gene trinucleotide repeat. Microsatellite instability was observed overall in only one of the 40 (2.5%) prostate adenocarcinomas studied. This replication error-positive tumor demonstrated repeat length alterations at two loci. Five other tumors showed an alteration in microsatellite size at a single locus. These tumors were not considered to have the microsatellite instability phenotype. All changes were identified either within tetranucleotide sequences or within the androgen receptor gene repeat (4 or 20 total markers analyzed). Both repeat length expansions and contractions were identified. The replication error-positive case also included separate metastatic nodal tissue. Additional microsatellite analysis of the metastatic tumor tissue revealed allelic patterns identical with the normal tissue control. Our data indicate that microsatellite instability is rare in prostate adenocarcinoma. Therefore, observation of this low replication error frequency suggests that most prostate carcinomas develop in the absence of widespread accumulation of somatic mutations in short tandem repeat sequences. Additionally, these genetic alterations appear to occur more often in tetranucleotide repeat sequences as well as in an androgen receptor gene trinucleotide repeat.

Two distinct Raf domains mediate interaction with Ras.

A key event for Ras transformation involves the direct physical association between Ras and the Raf-1 kinase. This interaction promotes both Raf translocation to the plasma membrane and activation of Raf kinase activity. Although substantial experimental evidence has demonstrated that Raf residues 51-131 alone are sufficient for Ras binding, conflicting observations have suggested that the Raf cysteine-rich domain (residues 139-184) may also be important for interaction with Ras. To clarify the role of the Raf cysteine-rich domain in Ras-Raf binding, we have compared the ability of two distinct Raf fragments to interact with Ras using both in vitro Ras binding and in vivo Ras inhibition assays. First, we determined that both Raf sequences 2-140 and 139-186 (designated Raf-Cys) showed preferential binding to active, GTP-bound Ras in vitro. Second, we observed that Raf-Cys antagonized oncogenic Ras(Q61L)-mediated transactivation of Ras-responsive elements and focus-forming activity in NIH 3T3 cells and insulin-induced germinal vesicle breakdown in Xenopus laevis oocytes in vivo. This inhibitory activity suggests that Raf-Cys can interact with Ras in vivo. Taken together, these results suggest that Ras interaction with two distinct domains of Raf-1 may be important in Ras-mediated activation of Raf kinase activity.

Use of proliferative markers Ki-67 (MIB-1) and proliferating cell nuclear antigen (PC10) in transitional cell carcinoma of the renal pelvis.

Segmental renal resection and improved endourological techniques have resulted in conservative treatment options for transitional cell carcinoma of the renal pelvis. These techniques have increased the need for more objective measures of biological behavior. We applied two immunohistochemical markers of cellular proliferation, proliferating cell nuclear antigen (PCNA; PC10) and Ki-67 (MIB-1), to 58 archival cases of renal pelvic transitional cell carcinomas and correlated the percentage of positive cells to grade, stage, and survival, and to one another; mitotic counts (mitoses/10 high-power fields) were also performed. Expression of PCNA showed a significant difference between grades 1, 2, and 3 tumors (P = 0.05) and between superficial (Ta, T1) and invasive tumors (T2-4) (P = 0.02). There was a significant overlap, however, in the percentage of cells staining between the grades as well as the stages. PCNA staining did not correlate with survival and did not identify a subset of patients with low-stage, low-grade tumors with a poorer prognosis. The Ki-67 score exhibited a stronger correlation with grade (P = 0.001), and there was a trend of increasing Ki-67 expression with higher stage tumors, but this did not reach statistical significance (P = 0.10). Ki-67 showed comparable findings to PCNA with regard to survival and overlap in staining between the grades and stages. Mitotic counts did correlate with grade (P = 0.003) but not stage or survival. This study demonstrates that cellular proliferation, as determined by the immunohistochemical markers, Ki-67 and PCNA, is related to grade and, to a lesser extent, stage, but the use of these markers as measures of biological behavior in clinical practice may be limited.

Anti-myeloperoxidase autoantibodies react with native but not denatured myeloperoxidase.

We wondered whether anti-myeloperoxidase (MPO) autoantibodies (MPO-ANCA) found in patients with systemic vasculitis react with a conformational epitope or epitopes on the MPO molecule. Sera from 15 human MPO-ANCA, and a polyclonal and a monoclonal anti-MPO antibodies were reacted with MPO in native and denatured states. Human MPO-ANCA and mouse monoclonal anti-MPO reacted with native MPO, and a 120-kD band representing the MPO hologenzyme, but not with denatured MPO fragments; however, MPO-ANCA and mouse anti-MPO did not demonstrate competitive inhibition of binding to MPO. Polyclonal rabbit anti-MPO reacted with both native and denatured MPO. All MPO-ANCA tested showed the same patterns of reactivity with native and denatured MPO in dot blot and Western blot analyses. Both polyclonal and monoclonal anti-MPO antibodies inhibited MPO's protein iodination by over 90%, whereas MPO-ANCA IgGs, normal IgGs and disease control IgGs did not. These data suggest that (i) MPO-ANCA interact with a conformational epitope on the MPO molecule; and (ii) MPO-ANCA from different patients have similar reactivity with native versus denatured MPO.

Antibodies against granule proteins activate neutrophils in vitro.

Polymorphonuclear leukocyte (PMN) respiratory burst was stimulated by heterologous antibodies against PMN granule proteins but not by control antibodies. Fluorescence-activated cell sorter (FACS) analysis of activated PMN demonstrated the presence of two primary granule proteins, proteinase 3 (PR-3) and cationic protein 57 (CAP-57) at the membrane surface. The presence of myeloperoxidase (MPO) at the cell surface of primed and unprimed PMN was confirmed by immunoelectron microscopy. Priming doses of recombinant tumor necrosis alpha (rTNF alpha) enhanced the rate of superoxide (O2-) production by these antibodies and increased the amount of surface protein accessible to these antibodies. Anti-neutrophil cytoplasmic autoantibodies (ANCA) with specificities for PMN granule proteins are present in patients with Wegener's granulomatosis, polyarteritis nodosa, and idiopathic and crescentic glomerulonephritis. The demonstration that antibodies against granule proteins activate PMN supports the hypothesis that the vasculitis seen in these diseases is due in part to PMN mediated oxidative injury following PMN stimulation by ANCA.

Anti-neutrophil cytoplasmic autoantibodies induce neutrophils to degranulate and produce oxygen radicals in vitro.

Anti-neutrophil cytoplasmic autoantibodies (ANCA) are in the circulation of most patients with pauci-immune necrotizing vasculitis and pauci-immune crescentic glomerulonephritis. The current study demonstrates an effect of these autoantibodies on neutrophil function in vitro. ANCA cause normal human neutrophils to undergo an oxidative burst and degranulate. Both ANCA phenotypes (i.e., cytoplasmic-pattern ANCA and myeloperoxidase-specific ANCA) induce neutrophil activation. ANCA sera and purified immunoglobulins significantly increase the release of reactive oxygen species when compared with controls. ANCA, in a dose-dependent manner, induce the release of primary granule contents. These effects are markedly enhanced by priming neutrophils with tumor necrosis factor. Flow cytometry studies demonstrate the presence of myeloperoxidase on the surface of neutrophils after cytokine priming, indicating that primed neutrophils have ANCA antigens at their surfaces to interact with ANCA. These observations suggest an in vivo pathogenetic role for ANCA. We propose that, in patients with necrotizing vasculitis, ANCA-induced release of toxic oxygen radicals and noxious granule enzymes from cytokine-primed neutrophils could be mediating vascular inflammation.

Ultrastructural localization of tartrate-resistant, purple acid phosphatase in rat osteoclasts by histochemistry and immunocytochemistry.

The intracellular localization of the tartrate-resistant purple acid phosphatase in osteoclasts of developing rat bone has been determined immunocytochemically using an antiserum to the purified bone-derived purple acid phosphatase. The localization of the immunoreactivity was compared with the results of enzyme histochemistry using p-nitrophenylphosphate as substrate and 10 mM tartrate. Both methods revealed the presence of the enzyme in numerous vesicles of various sizes up to 2-3 microns in diameter and in granules. There was no immunoreactivity in the Golgi apparatus, and tartrate completely inhibited the histochemical activity of this organelle. No consistent extracellular activity could be detected, nor was any reaction product observed at the ruffled border. The localization of the tartrate-resistant purple acid phosphatase in osteoclasts is consistent with an intracellular function for this enzyme.

Halogenation and anesthetic potency.

Previous studies have shown that the anesthetic potency of organic compounds increases as a given halogen is replaced with successively larger halogens. These studies often are limited in the accuracy of determination of potency, rarely correlate potency with physical properties, and usually fail to include ether compounds. Because establishing relationships between structure and activity may shed light on anesthetic action, we studied the new anesthetic, I-537 (CHF2-O-CHBr-CF3), relative to two other ether anesthetics, I-653 (CHF2-O-CHF-CF3) and isoflurane (CHF2-O-CHCl-CF3) for both of which MAC and oil/gas partition coefficients are accurately known. The oil/gas partition coefficient of I-537 at 37 degrees C was found to be 245 +/- 6 (mean +/- SD) and the MAC in Sprague-Dawley rats 0.52 +/- 0.07%. Increasing atomic weight of the 1-ethyl halogen (i.e., F in I-653, Cl in isoflurane, and Br in I-537) progressively decreases MAC (increases potency) and increases lipid solubility. Although potency and solubility change by more than 10-fold, the product of MAC and the oil/gas partition coefficient remains essentially constant (120 +/- 11). However, this product is significantly less than that for other inhaled anesthetics, a finding which either challenges the unitary theory of narcosis or suggests that the lipid solvent classically used to model the site of anesthetic action (olive oil) is inappropriate.