Community Engagement Practices at Research Centers in U.S. Minority Institutions: Priority Populations and Innovative Approaches to Advancing Health Disparities Research

This paper details U.S. Research Centers in Minority Institutions (RCMI) Community Engagement Cores (CECs): (1) unique and cross-cutting components, focus areas, specific aims, and target populations; and (2) approaches utilized to build or sustain trust towards community participation in research. A mixed-method data collection approach was employed for this cross-sectional study of current or previously funded RCMIs. A total of 18 of the 25 institutions spanning 13 U.S. states and territories participated. CEC specific aims were to support community engaged research (94%); to translate and disseminate research findings (88%); to develop partnerships (82%); and to build capacity around community research (71%). Four open-ended questions, qualitative analysis, and comparison of the categories led to the emergence of two supporting themes: (1) establishing trust between the community-academic collaborators and within the community and (2) building collaborative relationships. An overarching theme, building community together through trust and meaningful collaborations, emerged from the supporting themes and subthemes. The RCMI institutions and their CECs serve as models to circumvent the historical and current challenges to research in communities disproportionately affected by health disparities. Lessons learned from these cores may help other institutions who want to build community trust in and capacities for research that addresses community-related health concerns.

Extended-spectrum beta-lactamases in enterobacteriaceae in Buenos Aires, Argentina, public hospitals

Resistance to extended-spectrum cephalosporins is often associated with plasmid encoded extended spectrum beta-lactamases (ESBL). In order to evaluate the prevalence and diversity of ESBLs in enterobacteria in our city, a 1-month-period survey was carried out from April to May 2000. Extended-spectrum-cephalosporin-resistant strains, isolated from inpatient clinical specimens other than stools, were collected among 17 participating hospitals. From a total of 427 enterobacterial strains that were collected during this period, 39 were extended-spectrum cephalosporin resistant. The National Committee for Clinical Laboratory Standards' Screening and Confirmatory Tests for ESBL production were performed using cefotaxime and ceftazidime; cefepime and cefepime-clavulanic acid-containing disks were included. beta-Lactamases were characterized by isoelectric focusing and PCR amplification using specific primers. Three different ESBLs were detected: SHV-related (4 isolates), PER-2-type (9 isolates), and CTX-M-2-related (26 isolates). Sequencing of the corresponding genes confirmed CTX-M-2 in 19 of 21 and CTX-M-31 (an allelic variant) in the remaining 2 of 21. CTX-M-2 (or its variant) was detected in all Escherichia coli, Enterobacter aerogenes, Serratia marcescens, Proteus mirabilis, and Providencia stuartii strains, while PER-2 was detected in Enterobacter cloacae, E. aerogenes, and Klebsiella pneumoniae; SHV-related ESBL were found only in K. pneumoniae. These results clearly show that CTX-M-2 is the most prevalent ESBL produced by enterobacterial species isolated from public hospitals in Buenos Aires.

Insecticide resistance studies on Blattella germanica (Dictyoptera:Blattellidae) from Cuba

We studied the levels of resistance to seven insecticides: malathion, chlorpyrifos, pirimiphos-methyl, propoxur, cypermethrin, deltamethrin, and lambda-cyhalothrin in nine strains of Blattella germanica (Linnaeus, 1717) collected from sites in Santiago de Cuba and Havana City. The strains from Santiago de Cuba, generally had high levels of resistance to malathion, cypermethrin, deltamethrin, and lambda-cyhalothrin, but only low levels of resistance to pirimiphos-methyl, chlorpyrifos, and propoxur. In the strains from Havana City we found a moderate resistance to the organophosphate insecticides, resistance to the pyrethroids (except for three strains that showed susceptibility to lambda-cyhalothrin), and susceptibility to the carbamate insecticide (propoxur).

Exaggerated neurogenic inflammation and substance P receptor upregulation in RSV-infected weanling rats

Respiratory syncytial virus (RSV) infection in adult rats causes exaggerated inflammation after sensory nerve stimulation in the extrapulmonary, but not in the intrapulmonary airways. The goal of this study was to analyze neurogenic inflammation in weanling F-344 rats infected with RSV 18 +/- 2 d after birth. Five days after RSV inoculation, the extravasation of Evans blue-labeled albumin after nerve stimulation was significantly greater in the intrapulmonary airways of RSV-infected weanling rats than in pathogen-free control rats. In contrast, no difference was found in the extrapulmonary airways. The level of messenger RNA (mRNA) encoding the substance P (SP) receptor (neurokinin 1 [NK1]) increased fourfold in RSV-infected lungs, whereas mRNA encoding the VIPR1 receptor for the antiinflammatory vasoactive intestinal peptide (VIP) increased to a much lesser degree. mRNAs encoding the other neurokinin (NK2) and VIP (VIPR2) receptors were not affected by the virus. Selective inhibition of the NK1 receptor abolished neurogenic inflammation in RSV-infected intrapulmonary airways. Also, neurogenic inflammation and NK1 receptor upregulation in infected lungs were inhibited by prophylaxis with a monoclonal antibody against RSV. These data suggest that RSV lower respiratory tract infection makes the intrapulmonary airways of young rats abnormally susceptible to the proinflammatory effects of SP by selectively upregulating the expression of NK1 receptors.

A humanized monoclonal antibody against respiratory syncytial virus (palivizumab) inhibits RSV-induced neurogenic-mediated inflammation in rat airways

Respiratory syncytial virus (RSV) is the most important respiratory pathogen in infancy and early childhood and may predispose to subsequent lower respiratory tract illness. Recent data indicate that RSV up-regulates the substance P receptor, making the airways abnormally susceptible to the proinflammatory effects of this peptide released from sensory nerves. The present study was designed to determine whether the administration of RSV antibodies prevents the potentiation of neurogenic inflammation in rat airways. Five days after inoculation, sensory nerve-mediated extravasation of Evans blue-labeled albumin was significantly greater in the airways of RSV-infected rats than in pathogen-free controls. Polyclonal immune globulin enriched for RSV-neutralizing antibodies (RSVIG) reduced neurogenic extravasation when injected 24 h before intranasal inoculation of the virus but not when injected before endotracheal inoculation. A humanized MAb against RSV fusion protein (palivizumab) was twice as potent as RSVIG when given before intranasal inoculation and also caused significant inhibition after endotracheal inoculation. Furthermore, palivizumab inhibited neurogenic inflammation in RSV-infected rats when given 72 h after virus inoculation. These data suggest that palivizumab protects the respiratory tract from RSV-induced inflammation when given before or in the early phase of the viral infection. The administration of palivizumab to high-risk infants may limit the severity of the acute airway inflammation and may protect against subsequent lower respiratory tract illness.

RACK1, a protein kinase C anchoring protein, coordinates the binding of activated protein kinase C and select pleckstrin homology domains in vitro

The pleckstrin homology (PH) domain, identified in numerous signaling proteins including the beta-adrenergic receptor kinase (betaARK), was found to bind to various phospholipids as well as the beta subunit of heterotrimeric G proteins (Gbeta) [Touhara, K., et al. (1994) J. Biol. Chem. 269, 10217-10220]. Several PH domain-containing proteins are also substrates of protein kinase C (PKC). Because RACK1, an anchoring protein for activated PKC, is homologous to Gbeta (both contain seven repeats of the WD-40 motif), we determined (i) whether a direct interaction between various PH domains and RACK1 occurs and (ii) the effect of PKC on this interaction. We found that recombinant PH domains of several proteins exhibited differential binding to RACK1. Activated PKC and the PH domain of beta-spectrin or dynamin-1 concomitantly bound to RACK1. Although PH domains bind acidic phospholipids, the interaction between various PH domains and RACK1 was not dependent on the phospholipid activators of PKC, phosphatidylserine and 1, 2-diacylglycerol. Binding of these PH domains to RACK1 was also not affected by either inositol 1,4,5-triphosphate (IP(3)) or phosphatidylinositol 4,5-bisphosphate (PIP(2)). Our in vitro data suggest that RACK1 binds selective PH domains, and that PKC regulates this interaction. We propose that, in vivo, RACK1 may colocalize the kinase with its PH domain-containing substrates.

Respiratory syncytial virus upregulates expression of the substance P receptor in rat lungs

Respiratory syncytial virus (RSV) is a major respiratory pathogen in infants. The first goal of this study was to determine whether the infection following endotracheal inoculation of RSV in Fischer 344 rats results in increased inflammatory responses to substance P (SP) either released by capsaicin from sensory nerves or injected into the circulation. Five days after inoculation, the extravasation of Evans blue-labeled albumin after capsaicin or SP was significantly greater in RSV-infected airways than in pathogen-free controls. The peptide-degrading activity of the regulatory enzyme neutral endopeptidase was unaffected by RSV. However, SP(NK(1)) receptor mRNA levels increased fivefold in RSV-infected lungs, and the density of SP binding sites in the bronchial mucosa increased threefold. These data suggest that RSV makes the airways abnormally susceptible to the proinflammatory effects of SP by upregulating SP(NK(1)) receptor gene expression, thereby increasing the density of these receptors on target cells. This effect may contribute to the inflammatory reaction to the virus and could be a target for the therapy of RSV disease and its sequelae.

Multivisceral transplantation for megacystis microcolon intestinal hypoperistalsis syndrome

BACKGROUND

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare autosomal recessive disorder causing a functional neonatal bowel obstruction. Its etiopathogenesis is not fully understood. The prognosis is poor in the majority of cases; most patients die before the age of 6 months. In this report, we describe our experience with three patients with MMIHS in whom multivisceral transplantation was performed.

METHODS

Three patients with MMIHS underwent multivisceral transplantation. All patients were females with a history of long-term total parenteral nutrition (TPN) with TPN-related cholestatic liver disease.

RESULTS

Patient 1 died 17 months after transplantation because of aspiration after revision of her feeding gastrostomy. At the time of death, the graft was functioning and the patient was completely off TPN. Patient 2 is alive 17 months after transplant. She is a fully functional, active 2-year-old and has also recently begun oral feeding after intensive rehabilitation. Patient 3 died on day 44 of multisystem failure.

CONCLUSIONS

This is the first report in the literature of multivisceral transplantation for MMIHS. Although one of the three patients died 44 days after surgery from multiorgan system failure, the other two patients had long-term survival after transplant and both grew well on enteral feeding alone. One patient died 17 months from a non-transplant-related complication, while the other is living at home off of TPN, with almost complete dietary rehabilitation 17 months after transplant. Our case reports suggest that multivisceral transplantation is a valuable therapeutic option for patients affected by MMIHS with TPN-induced liver failure.

Characterization of the binding and phosphorylation of cardiac calsequestrin by epsilon protein kinase C

In this study, we report the cloning of the rat cardiac isoform of calsequestrin on the basis of its interaction with an epsilonprotein kinase C-unique sequence (epsilonV1) derived form the epsilonprotein kinase C regulatory domain. Calsequestrin binds activated epsilonprotein kinase C holoenzyme better than the inactive enzyme and nearly three times better than other protein kinase C isozymes. The interaction between epsilonprotein kinase C and calsequestrin is mediated by sequences in both the regulatory and kinase domains of the epsilonprotein kinase C. Finally, we show that calsequestrin is an epsilonprotein kinase C substrate in vitro and protein kinase C phosphorylation of calsequestrin leads to a decreased binding of epsilonprotein kinase C to calsequestrin.

Infantile hypertrophic cardiomyopathy of glycogenosis type IX: isolated cardiac phosphorylase kinase deficiency

Glycogen storage disease confined to the heart due to cardiac phosphorylase kinase deficiency causes a fatal infantile cardiomyopathy. Cardiomegaly can be detected in utero and is progressive. Electrocardiographic and echocardiographic findings are characteristic but not specific; these include large QRS complexes, short PR interval, and a hypertrophic nonobstructive pattern. Conclusive diagnosis requires biochemical analysis of myocardium, which may not be possible premortem due to the amount of tissue required. Pathologic examination of a standard cardiac biopsy can provide a presumptive diagnosis. There is no current treatment except a heart transplant. Infants succumb to heart failure and/or respiratory compromise due to pulmonary compression. This is a rare entity; only three cases have been reported to our knowledge. We report two additional cases.

Activation of epsilon protein kinase C correlates with a cardioprotective effect of regular ethanol consumption

In addition to decreasing the incidence of myocardial infarction, recent epidemiological data suggest that regular alcohol consumption improves survival after myocardial infarction. We recently found that chronic ethanol exposure induces long-term protection against cardiac ischemia-reperfusion injury, which improves myocardial recovery after infarction. Furthermore, this cardioprotection by ethanol is mediated through myocyte adenosine A1 receptors. We now determine the role of protein kinase C (PKC) in ethanol's protective effect against ischemia-reperfusion injury. Using perfused hearts of ethanol-fed guinea pigs, we find that improved contractile recovery and creatine kinase release after ischemia-reperfusion are abolished by PKC inhibition with chelerythrine. Western blot analysis and immunofluorescence localization demonstrate that regular ethanol consumption causes sustained translocation (activation) of epsilonPKC, but not delta or alphaPKC. This same isozyme is directly implicated in ischemic preconditioning's protection against ischemia-reperfusion injury. Our findings suggest (i) that regular ethanol consumption induces long-term cardioprotection through sustained translocation of epsilonPKC and (ii) that PKC activity is necessary at the time of ischemia to mediate ethanol's protective effect against ischemia-reperfusion injury. Studying this selective effect of ethanol on epsilonPKC activation may lead to new therapies to protect against ischemia-reperfusion injury in the heart and other organ systems.

The double-tuck model: a new animal model of arterial thrombosis

PURPOSE

To develop an animal model of a fibrin- and platelet-rich intraluminal arterial thrombus with abnormal mural substrate to simulate in situ thrombosis of human atherosclerotic arteries.

MATERIALS AND METHODS

Parallel studies of the crush-thrombin model (CT) and double-tuck model (DT) were performed and evaluated with use of angiography and histologic analysis. Ten Yorkshire swine (1-6 months; 20-30 kg; 10 females) underwent right femoral and carotid cutdowns performed after administration of general anesthesia (4 mL intravenous thiopental sodium, isoflurane 2% in 1 L of oxygen). After angiography, the CT model was created in the left carotid artery and the DT model was performed in the right carotid artery. Angiograms were obtained at 20 minutes (n = 1), at 1 hour (n = 3), at 2 hours (n = 4), and at 3 hours (n = 2) before sacrifice. After sacrifice, histologic specimens were stained with hematoxylin-eosin (H-E stain) and phosphotungstic acid hematoxylin for fibrin. The specimens were examined for endothelial irregularity and adhesion, platelet aggregation, fibrin layering, vessel wall injury, and adventitial hemorrhage. The findings were quantified as 0 = absent, 1+ = slight, 2+ = moderate, and 3+ = severe.

RESULTS

Angiographic results were similar. However, histologic analysis of the CT model showed severe damage to the arterial wall with dissection in nine of 10 animals. In the DT model, no dissection was found (n = 10). Endothelial irregularity was found in six of 10 arteries treated with the CT method, as compared with nine of 10 arteries prepared with the DT model; endothelial adhesion was found in five DT arteries and in four CT arteries. Platelet aggregation was present equally in both methods. A fibrin- and platelet-rich thrombus was created in five of 10 examined arteries by both methods.

CONCLUSIONS

The DT model creates endothelial irregularity leading to formation of a platelet- and fibrin-rich thrombus, adherent to the vessel wall without damage to the media. This contrasts with the CT method, which created medial dissection in nine of 10 arteries. One hour is the minimum time required to produce a good quality thrombus; 2 hours is the optimum time. The DT model is proposed as a useful tool in the development of new devices, drugs, and biotechnologic advances.

Estrogen as a psychotherapeutic agent

This article provides information on the effects of estrogen as a psychotherapeutic agent. Estrogen has a positive effect on several neurotransmitter systems that are assumed to be involved in regulation of affect, behavior, and cognition. Clinical studies suggest that an important cause of nonresponsiveness to antidepressants in postmenopausal women may be inadequate hormone replacement. Potential uses of estrogen as a mood stabilizer or mood enhancer also are described in this article. In the area of behavior, estrogen regulates aggressivity, sexual drive, impulsivity, and hostility. In terms of cognition, evidence suggests the importance of estrogen in the prevention and treatment of Alzheimer's-type dementia. At the end of the article, future research directions are discussed.

Treatment of depression in late life

Depression is a common problem in older patients and a significant contributor to morbidity and mortality in this population. The identification and treatment of depression is more complex in older patients because of difficulty in diagnosis, coexisting illnesses, and concurrent drug therapy. In addition, a variety of medical conditions and drugs can cause depression. Treatment often has to be modified in consideration of other illnesses, medications, and the reduced ability of the elderly to metabolize drugs. Duration of treatment may be longer than with young patients because older adults may respond more slowly to antidepressants.

Epstein-Barr virus-associated primary central nervous system lymphoma in a child with the acquired immunodeficiency syndrome. A case report and review of the literature

A 34-month-old black boy who had contracted acquired immunodeficiency syndrome from his mother presented with fever, vomiting, and cough. He was cachectic, hypertonic, and developmentally delayed. A brain computed tomography scan revealed masses in the left frontal horn, subependymal, and periventricular regions; secondary edema; and hydrocephalus. The differential diagnosis was cerebral lymphoma versus toxoplasmosis. The patient had disseminated Mycobacterium avium-intracellulare infection, lymphoid interstitial pneumonitis, as well as Pseudomonas and Klebsiella pneumonia. He died of respiratory insufficiency 53 days after admission. The autopsy confirmed a primary cerebral B-cell lymphoma, large cell type, which was positive for Epstein-Barr virus, latent phase, by in situ hybridization. Primary central nervous system lymphomas are rare in children, in contrast to adults. To our knowledge, only five well-documented cases of primary cerebral lymphomas in infants and children with acquired immunodeficiency syndrome have been reported previously. The current study shows that these childhood lymphomas are associated with and presumably caused by Epstein-Barr virus and thus have a pathogenesis similar to that of primary central nervous system lymphomas in adults.

Bilaterally multicentric synchronous Wilms' tumor: successful conservative treatment despite persistence of nephrogenic rests

We report a case of synchronous bilateral Wilms' tumor in a girl with incomplete Beck-with-Wiedemann syndrome and hemihypertrophy. Multiple small tumors were present in both kidneys. The initial diagnostic biopsy showed stage I monophasic blastematous Wilms' tumor of favorable histology, with multiple perilobar nephrogenic rests (nephroblastomatosis). By flow cytometry, tumor was diploid, with an S-phase fraction of 13.9%. Dactinomycin and vincristine were begun as per the National Wilms' Tumor Study IV (18 week course). After 1 month, only a single small lesion was evident, which persisted unchanged. Excisional biopsy 5 months after beginning chemotherapy showed entirely necrotic tumor but apparently unaltered nephrogenic rests. After completing chemotherapy, the child has done well, with normal renal function and no evidence of disease 3 years after diagnosis. Management of stage V Wilms' tumor is tailored to the individual case, being as conservative as possible to spare renal parenchyma. Given the high incidence of coexisting nephrogenic rests in bilateral Wilms' tumor, careful follow-up is required, as these potentially premalignant rests may resist chemotherapy.

Multinodular hyperplastic pannephric nephroblastomatosis with tubular differentiation: a new morphologic variant

We report a case of bilateral nephromegaly detected prenatally with oligohydramnios. Delivered at 35 weeks, this black male infant rapidly developed renal failure, requiring dialysis. He lived 3 1/2 months. The kidneys were three times normal size and diffusely multinodular, with hypoplastic calyces, no corticomedullary demarcation, and no pyramids. Histologically, they revealed hyperplastic embryonal rests composed of tubules and ducts with prominent branching. The nodular rests were intermixed with areas of mature parenchyma, which showed prominent oxalosis. By flow cytometry, rests were diploid, with an S-phase fraction of 25.9%. The proliferation of embryonal collecting system analogs is attributed to excessively rapid and prolonged branching of the ureteric bud, dating from the fourth gestational month or earlier. This unique case may represent a new morphologic variant of universal nephroblastomatosis.

Osseous manifestations of bacillary angiomatosis

We report a case of bacillary angiomatosis in a 32-year-old HIV-positive black Haitian male. Radiologic and pathologic features are presented.

Thrombotic thrombocytopenic purpura as the cause of death in an HIV-positive child

A case of fatal thrombotic thrombocytopenic purpura (TTP) in a pediatric patients with HIV infection is reported. The diagnosis was made at autopsy based on the presence of platelet microthrombi in multiple organs, including the cardiac conduction system. The disease presented atypically with hemorrhagic manifestations, thrombocytopenia, and hemolytic anemia, without significant accompanying neurologic and renal abnormalities. Autoimmune-based thrombocytopenia has been well documented in the presence of HIV infection in both the adult and the pediatric population. We believe this to be the first reported case of TTP in an HIV-positive child.

Bilateral hyperplastic nephromegaly, nephroblastomatosis, and renal dysplasia in a newborn: a variety of universal nephroblastomatosis

A preterm boy was born at 34 weeks. Prenatal ultrasonography showed oligohydramnios, fetal ascites, large kidneys, and small thorax. He died 21 h after birth of respiratory insufficiency. Autopsy revealed Potter's-like facies, hypoplastic lungs, ascites, and bilateral nephromegaly (renal weight almost 10 times normal). The kidneys were finely nodular externally, solid, and cerebriform on cut section. Histologically, they showed a diffusely distorted architecture of jumbled lobules, hyperplasia of cortical-type tissue with inconspicuous proximal tubules, relative hypoplasia of medullary tissue, tubulointerstitial dysplasia, and perilobar nephrogenic rests. The renal features represent a variety of the universal or panlobar (also called pancortical or infantile) type of nephroblastomatosis. To our knowledge, this is only the third such case reported. In the brain, each lateral ventricle contained a yellow gelatinous mass. Histologically, the masses consisted of a pseudomyxoid matrix with delicate fibers and focal adipocyte clusters, all confined within choroid plexus. We consider these lesions fibrolipomatous hamartomas.

Spondylocostal dysostosis with perinatal death and meningomyelocele

A preterm black girl was born at 35 weeks of gestation to a healthy nonconsanguineous couple. She had a very short trunk with disproportionately long extremities, mild prognathism, low-set ears, thoracolumbar meningomyelocele, and imperforate anus. She died 45 min after birth. Roentgenograms revealed hemivertebrae, block vertebrae, severe thoracic lordosis, absent sacrum, posterior fusion of some ribs with greater distance among them in the anterior thorax, and relatively long extremities. Internal examination showed an intact meningomyelocele extending from the first thoracic vertebra to the lumbosacral region, containing 150 mL of clear fluid. The lungs were severely hypoplastic. Spondylocostal dysostosis encompasses a spectrum of vertebral abnormalities ranging from spina bifida occulta to large meningomyelocele and from mild to severe thoracic deformities that produce pulmonary hypoplasia and respiratory insufficiency. Our case is one of the most severe ever described.

New findings in short rib syndrome

This white infant, born at 37 weeks of gestation, had a large cranium, bilateral anophthalmia, a midline cleft lip and palate, hypoplastic chest with short ribs, slightly protuberant abdomen, short limbs, bilateral single transverse palmar creases, a single umbilical artery, normal female external genitalia, normal (46 XY) chromosomes, and radiographic findings suggesting a short-rib (polydactyly) syndrome type IV (Beemer-Langer). Autopsy showed pulmonary hypoplasia, bilateral renal cystic dysplasia, intrahepatic bile duct cysts with periportal fibrosis, pancreatic cysts, absent internal genitalia, an atrophic optic chiasm, absent optic nerves, a single left anterior cerebral artery, polymicrogyria, and fusion of the frontal lobes, preoptic region, mammillary bodies, and thalami.

Cluster of iniencephaly in Miami

This report details a cluster of 5 cases of iniencephaly with anencephaly and rachischisis occurring over a 4-month period at Jackson Memorial Hospital/University of Miami Medical Center in Miami, Florida. All 5 cases of this rare, lethal, congenital malformation seen in the cluster included diaphragmatic defects with accompanying hernia, omphalocele, small adrenals, renal dysmaturity, gastrointestinal malformations, cleft lip and palate, and hypoplastic lungs. No single causative agent for this cluster was identified. A brief review of the literature regarding categorization of these malformations and as a discussion of the embryological basis for these lesions and possible etiologic factors are included.

cAMP levels in monocytes of heroin addicts

Intravenous heroin addicts have a high intracellular cAMP level in relation to control monocytes. Incubation in vitro with ascorbic acid normalizes the cellular content of cAMP. We discuss the role of cAMP in the pathogenesis of defective monocyte chemotaxis in intravenous heroin addicts.

Growth inhibition by exogenous proline and its metabolism in saltgrass (Distichlis spicata) suspension cultures

The growth of Distichlis spicata suspension cultures in LS medium without NaCl was inhibited 54% by 2 mM proline. In medium containing 260 mM NaCl, 10 mM proline inhibited growth by only 22%. The uptake and metabolism of 10 mM L-[1-(13)C] proline was followed by (13)C NMR and ninhydrin analyses of suspensions cultured in the presence of 0 or 260 mM NaCl. Uptake of 85 to 92% of the exogenous proline occurred within 72 h in all media. In 10 mM proline and no NaCl, cellular proline reached a maximm of 51.5 μmoles/g FW compared to 1.9 μmoles/g FW in suspensions not grown on proline. In medium containing 260 mM NaCl and proline, cellular proline reached 59-65 μmoles/g FW compared to 30-40 μmoles/g FW in controls grown without proline. The (13)C-label in the proline-C1 was either retained in proline or disappeared, presumably released as carbon dioxide, by catabolism through the TCA cycle. Since no metabolite of (13)C-proline was detected by NMR, proline was considered to be the molecule which inhibited the suspension culture growth.