Avoiding misclassification of acute kidney injury: Timing is everything

Accurate detection of acute kidney injury (AKI) in clinical trials is important. Using a 'baseline' creatinine from trial enrolment may not be ideal for understanding a participant's true baseline kidney function. We aimed to determine if a 'pre-trial baseline creatinine' resulted in comparable creatinine concentrations to a 'trial baseline creatinine', and how the timing of baseline creatinine affected the incidence of AKI in the Combination Antibiotic therapy for MEthicillin Resistant Staphylococcus aureus (CAMERA2) randomised trial. Study sites retrospectively collected a pre-trial baseline creatinine from up to 1 year before CAMERA2 trial enrolment ideally when the patient was medically stable. Baseline creatinine from CAMERA2 (the 'trial baseline creatinine'), was the highest creatinine measurement in the 24 h preceding trial randomisation. We used Wilcoxon sign rank test to compare pre-trial and trial baseline creatinine concentrations. We included 217 patients. The median pre-trial baseline creatinine was significantly lower than the median trial baseline creatinine (82 μmol/L [IQR 65-104 μmol/L] versus 86 μmol/L [IQR 66-152 μmol/L] p = <0.001). Using pre-trial baseline creatinine, 48 of 217 patients (22%) met criteria for an AKI at CAMERA2 enrolment and only 5 of these patients met criteria for an AKI using the CAMERA2 study protocol (using baseline creatinine from trial entry). Using a baseline creatinine from the time of trial enrolment failed to detect many patients with AKI. Trial protocols should consider the optimal timing of baseline creatinine and the limitations of using a baseline creatinine during an acute illness.

Improving palliative and supportive care in advanced cirrhosis: the HepatoCare model of integrated collaborative care

BACKGROUND

Patients with advanced cirrhosis experience an unpredictable disease trajectory but are infrequently referred to palliative care (PC) services and rarely undertake advance care planning (ACP).

AIM

We assessed whether a novel model of care increased provision of meaningful PC in advanced cirrhosis compared with standard of care (SOC).

METHODS

Thirty consecutive hepatology clinic outpatients with advanced cirrhosis, meeting one or more cirrhosis-related PC referral criteria, consented to treatment in the HepatoCare clinic (PC physician, specialist liver nurse, pharmacist) in parallel with usual specialist hepatology care. A control cohort of 30 consecutive outpatients with advanced cirrhosis undergoing SOC treatment was retrospectively identified for comparison. The primary outcome was provision of meaningful PC using HepatoCare versus SOC. Additional clinical outcomes were assessed over 12 months or until death and significant differences were identified.

RESULTS

The intervention and control cohorts had similarly advanced cirrhosis (mean Child-Pugh scores 8.7 vs 8.2, P = 0.46; mean model for end-stage liver disease scores 14.4 vs 14.6, P = 0.88) but a lower 12-month mortality rate (33% HepatoCare vs 67% SOC; P = 0.02). The intervention cohort experienced higher uptake of formal ACP (100% vs 25% for the control cohort) and outpatient PC referral (100% vs 40%), and were more likely to die at home or in a PC bed/hospice (80% vs 30%). The majority of the HepatoCare cohort (81%) had medications safely deprescribed and experienced fewer unplanned admission days (470 vs 794).

CONCLUSIONS

HepatoCare is a novel multidisciplinary model of care that integrates effective PC and specialist hepatology management to improve outcomes in advanced cirrhosis.

Early oral antibiotic switch in Staphylococcus aureus bacteraemia: The Staphylococcus aureus Network Adaptive Platform (SNAP) Trial Early Oral Switch Protocol

BACKGROUND

Staphylococcus aureus bloodstream infection (bacteraemia) is traditionally treated with at least two weeks of IV antibiotics in adults, 3-7 days in children, and often longer for those with complicated disease. The current practice of treating S. aureus bacteraemia (SAB) with prolonged IV antibiotics (rather than oral antibiotics) is based on historical observational research and expert opinion. Prolonged IV antibiotic therapy has significant disadvantages for patients and healthcare systems, and there is growing interest in whether a switch to oral antibiotics following an initial period of IV therapy is a safe alternative for clinically stable patients.

PROTOCOL

The early oral switch (EOS) domain of the S. aureus Network Adaptive Platform (SNAP) trial will assess early switch to oral antibiotics compared with continued IV treatment in clinically stable patients with SAB. The primary endpoint is 90-day all-cause mortality. Hospitalised SAB patients are assessed at platform day 7 +/- 2 (uncomplicated SAB) and day 14 +/-2 (complicated SAB) to determine their eligibility for randomisation to EOS (intervention) or continued IV treatment (current standard of care).

DISCUSSION

Recruitment is occurring to the EOS domain of the SNAP trial. As of August 2023, 21% of all SNAP participants had been randomised to the EOS domain, a total of 264 participants across 77 centres, with an aim to recruit at least 1000 participants. We describe challenges and facilitators to enrolment in this domain to aid those planning similar trials.

Optimal drug therapy for Staphylococcus aureus bacteraemia in adults

PURPOSE OF REVIEW

Staphylococcus aureus is a significant human pathogen, causing a variety of infections, from skin and soft tissue infections to endocarditis, bone and joint infections and deep tissue abscesses. Mortality from S. aureus bacteraemia remains high, without major therapeutic advances in recent decades.

RECENT FINDINGS

In recent years, optimized dosing of antibiotics is increasingly being recognized as a cornerstone of management for severe infections including S. aureus bacteraemia. This comprehensive review details the pharmacokinetics/pharmacodynamics (PK/PD) targets for commonly used antistaphylococcal antibiotics and the doses predicted to achieve them in clinical practice. Recent advances in dosing of teicoplanin and use of cefazolin in CNS infections and findings from combination therapy studies are discussed. Drug exposure relationships related to toxicity are also detailed.

SUMMARY

This review details the different PK/PD targets for drugs used to treat S. aureus bacteraemia and how to apply them in various scenarios. The drug doses that achieve them, and the risks of toxicity are also provided.

Longer-term Mortality and Kidney Outcomes of Participants in the Combination Antibiotics for Methicillin-Resistant Staphylococcus aureus (CAMERA2) Trial: A Post Hoc Analysis

Background

The Combination Antibiotic Therapy for Methicillin-Resistant Staphylococcus aureus (CAMERA2) trial ceased recruitment in July 2018, noting that a higher proportion of patients in the intervention arm (combination therapy) developed acute kidney injury (AKI) compared to the standard therapy (monotherapy) arm. We analyzed the long-term outcomes of participants in CAMERA2 to understand the impact of combination antibiotic therapy and AKI.

Methods

Trial sites obtained additional follow-up data. The primary outcome was all-cause mortality, censored at death or the date of last known follow-up. Secondary outcomes included kidney failure or a reduction in kidney function (a 40% reduction in estimated glomerular filtration rate to <60 mL/minute/1.73 m²). To determine independent predictors of mortality in this cohort, adjusted hazard ratios were calculated using a Cox proportional hazards regression model.

Results

This post hoc analysis included extended follow-up data for 260 patients. Overall, 123 of 260 (47%) of participants died, with a median population survival estimate of 3.4 years (235 deaths per 1000 person-years). Fifty-five patients died within 90 days after CAMERA2 trial randomization; another 68 deaths occurred after day 90. Using univariable Cox proportional hazards regression, mortality was not associated with either the assigned treatment arm in CAMERA2 (hazard ratio [HR], 0.84 [95% confidence interval [CI], .59-1.19]; P = .33) or experiencing an AKI (HR at 1 year, 1.04 [95% CI, .64-1.68]; P = .88).

Conclusions

In this cohort of patients hospitalized with methicillin-resistant S aureus bacteremia, we found no association between either treatment arm of the CAMERA2 trial or AKI (using CAMERA2 trial definition) and longer-term mortality.

Beta-Lactam Dose Optimisation in the Intensive Care Unit: Targets, Therapeutic Drug Monitoring and Toxicity

Beta-lactams are an important family of antibiotics used to treat infections and are commonly used in critically ill patients. Optimal use of these drugs in the intensive care unit (ICU) is important because of the serious complications from sepsis. Target beta-lactam antibiotic exposures may be chosen using fundamental principles of beta-lactam activity derived from pre-clinical and clinical studies, although the debate regarding optimal beta-lactam exposure targets is ongoing. Attainment of target exposures in the ICU requires overcoming significant pharmacokinetic (PK) and pharmacodynamic (PD) challenges. For beta-lactam drugs, the use of therapeutic drug monitoring (TDM) to confirm if the desired exposure targets are achieved has shown promise, but further data are required to determine if improvement in infection-related outcomes can be achieved. Additionally, beta-lactam TDM may be useful where a relationship exists between supratherapeutic antibiotic exposure and drug adverse effects. An ideal beta-lactam TDM service should endeavor to efficiently sample and report results in identified at-risk patients in a timely manner. Consensus beta-lactam PK/PD targets associated with optimal patient outcomes are lacking and should be a focus for future research.

Sotrovimab use in young pediatric patients at high-risk of progression to severe COVID-19 disease

This retrospective analysis describes the administration of sotrovimab in 32 children (22 aged 12 to 16 years old; 10 aged 1-11 years old) who were at high risk of deterioration to severe COVID-19 disease. We provide dosing suggestions and demonstrate the feasibility of sotrovimab use in the younger pediatric population (<12 years old and <40 kg).

Risk Factors for Nephrotoxicity in Methicillin-Resistant Staphylococcus aureus Bacteraemia: A Post Hoc Analysis of the CAMERA2 Trial

BACKGROUND

Clinical risk factors for nephrotoxicity in Staphylococcus aureus bacteraemia remain largely undetermined, despite its common occurrence and clinical significance. In an international, multicentre, prospective clinical trial (CAMERA2), which compared standard therapy (vancomycin monotherapy) to combination therapy (adding an anti-staphylococcal beta-lactam) for methicillin-resistant S. aureus bacteraemia, significantly more people in the combination therapy arm experienced acute kidney injury compared with those in the monotherapy arm (23% vs 6%).

OBJECTIVE

The aim of this post hoc analysis was to explore in greater depth the risk factors for acute kidney injury from the CAMERA2 trial.

METHODS

Among participants of the CAMERA2 trial, demographic-related, infection-related and treatment-related risk factors were assessed for their relationship with acute kidney injury by univariable and multivariable logistic regression. Acute kidney injury was defined by a modified-KDIGO (Kidney Disease: Improving Global Outcomes) criteria (not including urinary output).

RESULTS

Of the 266 participants included, age (p = 0.04), randomisation to combination therapy (p = 0.002), vancomycin area under the concentration-time curve (p = 0.03) and receipt of (flu)cloxacillin as the companion beta-lactam (p < 0.001) were significantly associated with acute kidney injury. On a multivariable analysis, concurrent use of (flu)cloxacillin increased the risk of acute kidney injury over four times compared with the use of cefazolin or no beta-lactam. The association of vancomycin area under the concentration-time curve with acute kidney injury also persisted in the multivariable model.

CONCLUSIONS

For participants receiving vancomycin for S. aureus bacteraemia, use of (flu)cloxacillin and increased vancomycin area under the concentration-time curve were risk factors for acute kidney injury. These represent potentially modifiable risk factors for nephrotoxicity and highlight the importance of avoiding the use of concurrent nephrotoxins.

Study protocol: Australasian Registry of Severe Cutaneous Adverse Reactions (AUS-SCAR)

INTRODUCTION

Severe cutaneous adverse reactions (SCAR) are a group of T cell-mediated hypersensitivities associated with significant morbidity, mortality and hospital costs. Clinical phenotypes include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalised exanthematous pustulosis (AGEP). In this Australasian, multicentre, prospective registry, we plan to examine the clinical presentation, drug causality, genomic predictors, potential diagnostic approaches, treatments and long-term outcomes of SCAR in Australia and New Zealand.

METHODS AND ANALYSIS

Adult and adolescent patients with SCAR including SJS, TEN, DRESS, AGEP and another T cell-mediated hypersensitivity, generalised bullous fixed drug eruption, will be prospectively recruited. A waiver of consent has been granted for some sites to retrospectively include cases which result in early mortality. DNA will be collected for all prospective cases. Blood, blister fluid and skin biopsy sampling is optional and subject to patient consent and site capacity. To develop culprit drug identification and prevention, genomic testing will be performed to confirm human leukocyte antigen (HLA) type and ex vivo testing will be performed via interferon-γ release enzyme linked immunospot assay using collected peripheral blood mononuclear cells. The long-term outcomes of SCAR will be investigated with a 12-month quality of life survey and examination of prescribing and mortality data.

ETHICS AND DISSEMINATION

This study was reviewed and approved by the Austin Health Human Research Ethics Committee (HREC/50791/Austin-19). Results will be published in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12619000241134).

Exploring the Role of Traumatic Event Exposure in Tobacco Dependence Treatment Outcomes Among African Americans

African Americans are more likely to die from tobacco-related diseases and less likely to quit smoking than their white counterparts. Evidence of greater prevalence of posttraumatic stress disorder (PTSD) among African Americans underscores the importance of studying the effects of traumatic event exposure on tobacco dependence treatment outcomes in this group. In this secondary analysis of data from a previously completed randomized control trial, we examined the effects of traumatic event exposure (e.g., serious accident) on tobacco dependence treatment outcomes, as well its moderating effects on the effectiveness of an adapted smoking cessation treatment, in a sample (n = 169) of African American smokers in New York City. Traumatic event exposure did not have a significant impact on tobacco treatment outcomes and did not moderate the relationship between treatment type and outcomes in this sample. While results may be driven by unique sample characteristics, they may also indicate that an average level of traumatic event exposure does not significantly impact tobacco treatment outcomes among African Americans. Future research should examine the effects of higher levels of traumatic event exposure on treatment outcomes, as well as investigating the factors underlying trauma-exposed individuals' difficulties with reducing/quitting smoking in a larger, more diverse African American sample.

Plasma concentrations resulting from continuous infusion of meropenem in a community-based outpatient program: A case series

PURPOSE

Traditionally meropenem has been considered too unstable in solution for continuous infusion. However, in the era of increasing antimicrobial resistance, use of meropenem is becoming more frequently required, and the ability to facilitate its administration via community-based programs would be beneficial. There are some reassuring data about meropenem stability in solution, but data about actual drug exposure in patients and subsequent clinical outcomes are lacking.

SUMMARY

Here we present a case series of 4 patients at a single tertiary center who received meropenem via continuous infusion coordinated through an outpatient parenteral antimicrobial treatment (OPAT) program. We provide plasma drug concentrations achieved and report on the patients' clinical progress. All patients achieved drug concentrations of at least 2 times the minimum inhibitory concentration (MIC) while receiving meropenem via continuous infusion and had resolution of their infectious complications. No adverse effects of meropenem continuous infusion were noted.

CONCLUSION

Meropenem continuous infusion along with therapeutic drug monitoring was used successfully in a community-based program. Due to interpatient pharmacokinetic variability, we consider meropenem concentration monitoring compulsory during continuous-infusion meropenem therapy.

The MOBILISE study: utilisation of ambulatory pumps in the inpatient setting to administer continuous antibiotic infusions-a randomised controlled trial

In the inpatient setting, antibiotics are generally administered via bedside pumps with multiple daily dosing. Utilisation of a continuous antibiotic infusion (CAI) instead might have patient and nursing satisfaction, workflow efficiencies and infection control benefits. We aimed to study the utilisation of CAI in the inpatient setting for routine antibiotic administration. Patients receiving a peripherally inserted central venous catheter (PICC) for antibiotic administration were screened for the study. The patients were randomised to either (1) standard pump and intermittent antibiotic administration (IAA) or (2) CAI via an ambulatory pump. An accelerometer placed on the ankle was used to assess patient activity. Nursing and patient satisfaction surveys were also carried out. Forty patients met the study criteria for enrolment with 21 patients being enrolled in the CAI arm of the study. One hundred and five days of accelerometer recordings were available for analysis. The geometric mean activity was 45 min/day in the standard arm and 64 min/day in the CAI arm. This represented a 42% (95% CI: -14 to 133%, p = 0.16) difference in activity between the two groups. Nursing staff reported that they spent less time throughout their shift attending the antibiotic line or pump in patients who were in the CAI arm of the study (p < 0.001). In addition, patients in this arm of the study were more likely to recommend this method of administration of antibiotics to a family member (p =0.0001). The MOBILISE study showed nursing and patient satisfaction when CAI were utilised in the inpatient setting. A statistically non-significant difference in mobility was seen. The trial was registered (28/03/2018) with the Australia New Zealand Clinical Trials Registry (ACTRN12618000452291).

Contemporaneous management of ampicillin infusions in the outpatient setting through the use of therapeutic drug monitoring

The use of ampicillin in the outpatient setting has traditionally been avoided because of the short half-life and instability in solution of this drug. However, recent in vitro data and two case series support the safe and effective administration of ampicillin by continuous infusion in the community. Therapeutic drug monitoring (TDM) of beta-lactam antibiotics can be used to optimise antibiotic exposure and ensure adequate clinical responses. A case series is presented of patients receiving ampicillin via prolonged infusion in the outpatient setting, with TDM to ensure adequate plasma antibiotic levels were achieved. Three patients who received ampicillin by continuous infusion under the Outpatient Parenteral Antimicrobial Therapy (OPAT) program are described, including details of antibiotic dose and steady-state plasma drug concentration as measured by high-performance liquid chromatography. All three patients had an infection with ampicillin-susceptible Enterococcus faecalis; one patient had post-partum endometritis, one had urosepsis and one had a complex polymicrobial bone and joint infection. Adequate plasma drug levels were achieved in all patients. Management of the antibiotic temperature and infusion times, and appropriate timing of drug levels in the community were required. Two patients achieved clinical cure, while the third required further surgical debridement and antibiotic therapy. TDM in this setting enabled the contemporaneous management and dose alteration of ampicillin. Ampicillin may be a safe and effective drug when administered by continuous infusion with appropriate TDM in the community setting.

Declining soil transmitted helminth detections in an Australian tropical region

Soil-transmitted helminths (STHs), are recognised neglected tropical diseases and have been endemic in patients in tropical Northern Australia. We reviewed the temporal trends in detections of STHs and Hymenolepis nana in faecal samples from Northern Territory (NT) Government Health facilities, representing patients with acute illnesses and comorbidities between 2008 and 2018. Ascaris lumbricoides is not detected in patients in the NT. The number of faecal samples examined yearly was relatively constant with a median of 4458 (range 4246-4933). Faecal samples from patients under the age of 5 years declined by 45% over the 11 years of the study. Detections of Trichuris trichiura, Strongyloides spp., and hookworm ova fell significantly by 89% (p<0.001), 71% (p<0.001), and 43% (p<0.01), respectively, over the 11 years. Detections of H. nana declined by 33% absolutely, but not significantly, when assessed relative to the reduction in faecal samples from patients under the age of 5 years. The marked reduction in STH numbers coincided with a 10-fold increase in NT dispensing of ivermectin, predominantly used for scabies control, in widely geographically spaced locations throughout the NT, over the 11 years of the study. Our data support previous findings of the beneficial collateral effects of ivermectin therapy. Ivermectin is not recognised as having anti-cestode activity, hence the continued presence of H. nana endemically in the NT, suggests declines in STHs are not related to other changes in health hardware or existing mass drug administration programs. The reduction in T. trichiura detections may not be explained by this association, as unlike Strongyloides spp., the anti-helminthic effect of ivermectin has been less marked.

Opsin co-expression in Limulus photoreceptors: differential regulation by light and a circadian clock

A long-standing concept in vision science has held that a single photoreceptor expresses a single type of opsin, the protein component of visual pigment. However, the number of examples in the literature of photoreceptors from vertebrates and invertebrates that break this rule is increasing. Here, we describe a newly discovered Limulus opsin, Limulus opsin5, which is significantly different from previously characterized Limulus opsins, opsins1 and 2. We show that opsin5 is co-expressed with opsins1 and 2 in Limulus lateral and ventral eye photoreceptors and provide the first evidence that the expression of co-expressed opsins can be differentially regulated. We show that the relative levels of opsin5 and opsin1 and 2 in the rhabdom change with a diurnal rhythm and that their relative levels are also influenced by the animal's central circadian clock. An analysis of the sequence of opsin5 suggests it is sensitive to visible light (400-700 nm) but that its spectral properties may be different from that of opsins1 and 2. Changes in the relative levels of these opsins may underlie some of the dramatic day-night changes in Limulus photoreceptor function and may produce a diurnal change in their spectral sensitivity.

Cyclic AMP: a mitogenic signal for Swiss 3T3 cells

Addition of cholera toxin (100 ng/ml) to quiescent cultures of Swiss 3T3 cells acts synergistically with serum (2-4%), insulin, phorbol esters, epidermal growth factor, and fibroblast-derived growth factor to stimulate DNA synthesis. In the presence of insulin, cholera toxin caused a dose-dependent increase in cumulative [3H]thymidine incorporation into acid-insoluble material and in the intracellular cyclic AMP (cAMP) level. The dose--response curves for the two processes were similar. Furthermore, addition of 1-methyl-3-isobutylxanthine (15--500 microM) or of 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (5--100 microM), both of which are potent inhibitors of cyclic nucleotide phosphodiesterase which are potent inhibitors of cyclic nucleotide phosphodiesterase activity, stimulated DNA synthesis and increased cAMP levels in Swiss 3T3 cells. These compounds strikingly potentiated the effect of cholera toxin on DNA synthesis and on cAMP levels. When quiescent Swiss 3T3 cells were exposed to cholera toxin (100 ng/ml) and insulin at 10 micrograms/ml (4- to 7-fold increase in cAMP level) or to these agents and 1-methyl-3-isobutyl xanthine at 50 microM (35-fold increase in cAMP level), DNA synthesis began after a lag of 16 hr. These results indicate that cAMP acts as a mitogenic signal for Swiss 3T3 cells and differ from the widely held view that cyclic AMP inhibits the proliferation of fibroblast cells.

Melittin stimulates Na entry, Na-K pump activity and DNA synthesis in quiescent cultures of mouse cells

Melittin, an amphipatic polypeptide, increases several fold the activity of Na-K pump in quiescent Swiss 3T3 cells. As with other growth factors, melittin increases the activity of the pump by increasing Na entry into the cell. In contrast, other early responses are not elicited by the toxin. At concentrations that promote ion fluxes, melittin stimulates DNA synthesis in quiescent mouse cells acting synergistically with insulin, epidermal growth factor and with the growth factor released by SV40 BHK cells. In contrast, melittin does not interact synergistically with either phorbol esters of vasopressin. The cellular effects of melittin are consistent with the proposal that ion fluxes signal the initiation of mitogenesis in quiescent cells.

Antitubulin agents enhance the stimulation of DNA synthesis by polypeptide growth factors in 3T3 mouse fibroblasts

Colchicine and other antitubulin agents markedly enhanced the stimulation of DNA synthesis by combinations of various growth factors such as epidermal growth factor, insulin, fibroblast-derived growth factor, and vasopressin in serum-free cultures of several quiescent 3T3 mouse fibroblast cell lines. Enhancing effects were observed based on continuous incorporation of [3H]thymidine into DNA as well as by autoradiographic labeling of cell nuclei. The concentration of colchicine and podophyllotoxin required to produce half-maximal enhancement of DNA synthesis stimulated by epidermal growth factor and insulin was 25-50 nM. Lumicolchicine did not produce enhancing effects. The disassembly of microtubules resulting from the action of colchicine, Colcemid, and vinblastine did not inhibit the stimulation of DNA synthesis in quiescent Swiss 3T3 fibroblasts by fetal bovine serum. We conclude that the cytoplasmic microtubule network in 3T3 mouse fibroblasts does not exert a positive regulatory function in the initiation of DNA synthesis but rather can produce a constraint on the initial action of the peptide growth factors in serum-free media.

Vasopressin stimulation of mouse 3T3 cell growth

Vasopressin is shown to be a potent mitogen for Swiss 3T3 cells. The hormone (1--10 ng/ml) causes a striking shift of the dose--response curve for the effect of serum on thymidine incorporation by cultures of 3T3 cells arrested in the G1/G0 phase of the cell cycle. In the absence of added serum, the effect of vasopressin on DNA synthesis is greatly potentiated by insulin, epidermal growth factor, and a factor isolated from medium conditioned by simian virus 40-infected baby hamster kidney cells. The mitogenic effect of vasopressin is dependent on time and hormone concentration. In the presence of insulin, the half-maximal effect elicited by the peptide is obtained at 0.6 ng/ml. [Arg]Vasopressin and [Lys]vasopressin are equally potent. The vasopressins are 10(3)-fold more potent than oxytocin. In the presence of a low (2.5%) concentration of serum, vasopressins stimulate cell proliferation.

Glycolysis in quiescent cultures of 3T3 cells. Stimulation by serum, epidermal growth factor, and insulin in intact cells and persistence of the stimulation after cell homogenization

Addition of serum to quiescent cultures of 3T3 cells rapidly increases lactic acid formation and subsequently stimulates cell division. The stimulation of lactic acid production is seen at high, saturating concentrations of extra-cellular glucose. It is dependent on the time of exposure and on the dose of serum and is not blocked by the addition of cycloheximide, puromycin, or actinomycin D. In contrast, serum only marginally affects glycolysis by rapidly growing 3T6 or SV40-3T3 cells. In addition to serum, epidermal growth factor (0.1 to 10 ng/ml) and insulin (10 to 500 ng/ml) cause a striking stimulation of glycolysis in quiescent 3T3 cells. Neither exogenous cyclic nucleotides nor ouabain effect the glycolytic response, but the presence of Ca2+ markedly influences the activation of glycolysis by epidermal growth factor and by insulin. A novel finding in this study is that homogenates prepared from quiescent cells treated with serum, epidermal growth factor, or insulin show increased glycolysis as compared with homogenates from nonstimulated cultures. This finding will allow further experimental analysis of the cause of increased glycolysis in rapidly proliferating cells.