Preventative strategies for low anterior resection syndrome.

BACKGROUND: A common and debilitating complication of low anterior resection for rectal cancer is low anterior resection syndrome (LARS). As a multifactorial entity, LARS is poorly understood and challenging to treat. Despite this, prevention strategies are commonly overlooked. Our aim was to review the pathophysiology of LARS and explore current evidence on the efficacy and feasibility of prophylactic techniques. METHODS: A literature review was performed between [1st January 2000 to 1st October 2023] for studies which investigated preventative interventions for LARS. Mechanisms by which LARS develop are described, followed by a review of prophylactic strategies to prevent LARS. Medline, Cochrane, and PubMed databases were searched, 189 articles screened, 8 duplicates removed and 18 studies reviewed. RESULTS: Colonic dysmotility, anal sphincter dysfunction and neorectal dysfunction all contribute to the development of LARS, with the complex mechanism of defecation interrupted by surgery. Transanal irrigation (TAI) and pelvic floor rehabilitation (PFR) have shown benefits in preventing LARS, but may be limited by patient compliance. Intraoperative nerve monitoring (IONM) and robotic-assisted surgery have shown some promise in surgically preventing LARS. Nerve stimulation and other novel strategies currently used in treatment of LARS have yet to be investigated in their roles prophylactically. CONCLUSIONS: To date, there is a limited evidence base for all preventative strategies including IONM, RAS, PFP and TAI. These strategies are limited by either access (IONM, RAS and PFP) or acceptability (PFP and TAI), which are both key to the success of any intervention. The results of ongoing trials will serve to assess acceptability, while technological advancement may improve access to some of the aforementioned strategies.

PROSPECT guideline for tonsillectomy: systematic review and procedure-specific postoperative pain management recommendations.

Tonsillectomy is one of the most frequently performed surgical procedures; however, pain management remains challenging. Procedure-specific efficacy as well as specific risks of treatment options should guide selection of pain management protocols based on evidence and should optimise analgesia without harm. The aims of this systematic review were to evaluate the available literature and develop recommendations for optimal pain management after tonsillectomy. A systematic review utilising preferred reporting items for systematic reviews and meta-analysis guidelines with procedure-specific postoperative pain management (PROSPECT) methodology was undertaken. Randomised controlled trials published in the English language up to November 2019 assessing postoperative pain using analgesic, anaesthetic or surgical interventions were identified. Out of the 719 potentially eligible studies identified, 226 randomised controlled trials met the inclusion criteria, excluding the studies examining surgical techniques. Pre-operative and intra-operative interventions that improved postoperative pain were paracetamol; non-steroidal anti-inflammatory drugs; intravenous dexamethasone; ketamine (only assessed in children); gabapentinoids; dexmedetomidine; honey; and acupuncture. Inconsistent evidence was found for local anaesthetic infiltration; antibiotics; and magnesium sulphate. Limited evidence was found for clonidine. The analgesic regimen for tonsillectomy should include paracetamol; non-steroidal anti-inflammatory drugs; and intravenous dexamethasone, with opioids as rescue analgesics. Analgesic adjuncts such as intra-operative and postoperative acupuncture as well as postoperative honey are also recommended. Ketamine (only for children); dexmedetomidine; or gabapentinoids may be considered when some of the first-line analgesics are contra-indicated. Further randomised controlled trials are required to define risk and combination of drugs most effective for postoperative pain relief after tonsillectomy.

Articular surface mounted navigated total knee arthroplasty improves the reliability of component alignment.

PURPOSE: The primary aim was to compare the early knee-specific functional outcome after articular surface mounted (ASM) navigation with non-navigated TKA. The secondary aims were to compare general physical and mental health improvement, patient satisfaction, and reliability of component alignment in the sagittal and coronal planes between ASM navigated TKA with that of non-navigated TKA. METHODS: Prospective functional outcome and radiographic data were collect for 123 patients undergoing ASM navigation and 172 patients undergoing non-navigated TKA by a high volume single surgeon. Pre-operative and one-year Oxford knee score (OKS) and short form (SF-) 12 scores were collected. Patient satisfaction was also assessed at one year. Implant position was assessed on post-operative radiographs (alpha, beta, gamma, and sigma angles) by a blinded observer. RESULTS: There was no significant difference for improvement in OKS, SF-12 physical or mental components, or satisfaction between the groups one year following surgery. The non-navigation group was significantly more likely to have outliers (greater than 3 degrees) in femoral varus/valgus coronal alignment [odds ratio (OR) 4.5, 95% confidence interval (CI) 1.0-20.7, p = 0.049] and for posterior tibial slope (OR 8.3, 95% CI 1.1-65.0, p = 0.03). CONCLUSIONS: ASM navigation significantly reduces the number of outliers for the femoral and tibial components when compared to conventional non-navigation alignment. However, the short-term functional outcome is not influenced by the surgical technique used. If the surgeon wants to reduce their number of outliers, then ASM navigation should be considered but the overall functional outcome in the short term is not influenced. LEVEL OF EVIDENCE: III Therapeutic investigation, retrospective cohort study.

Upper airway obstruction assessment: Peak inspiratory flow and clinical COPD Questionnaire.

OBJECTIVES: Spirometric evaluation of upper airway obstruction (UAO) is not commonly performed by Otolaryngologists. In addition, functional evaluation of UAO by flow-volume loops (FVL) is not available in all clinical settings. More recently, peak inspiratory flow (PIF) has proven to be a useful tool to monitor UAO at the patient's bedside. The aim of this work is to assess the role of PIF measured with a simple flow metre (In-Check method) as a standardised, simple, non-invasive tool in quantifying chronic and subacute UAO in a routine clinical practice. In addition, a Clinical COPD Questionnaire (CCQ), previously validated to assess the psychophysical status in patients with laryngotracheal stenosis, was utilised to evaluate respiratory function in UAO. DESIGN: Prospective cohort study. SETTINGS: University teaching hospital. PARTICIPANTS: Seventy 2 subjects, an UAO group of 26 patients and a control group of 46 healthy subjects. MAIN OUTCOME MEASURES: The ability of PIF values to discriminate between the UAO group and the control group was assessed using a ROC curve. A Spearman rank correlation was used to test the relationship between PIF measurements and the global CCQ score. Additionally, an analysis of CCQ at domain and items levels was performed. RESULTS: Peak inspiratory flow values were accurate, with an area under the ROC curve (AUC) of 0.98 (P < .05) for differentiating the control group from the UAO group. A threshold PIF value of 170 L/min was found for diagnosing UAO. An inconclusive negative trend was found (r = -.19; P = .35) between PIF values and CCQ global score. Concerning CCQ, the symptoms domain was the most affected by UAO, higher than mental domains (P < .001) as well as functional domains (P < .01). Exertional dyspnoea and cough were the items that obtained the highest disturbed scores. CONCLUSIONS: Peak inspiratory flow is a non-invasive, quantitative parameter to evaluate the severity of UAO. Testing can be easily performed in a routine clinical setting, with a non-expensive hand-held device, and could help medical follow-up programmes and prevent emergency situations. However, FVL may be necessary for further assessment of UAO diseases. The CCQ confirms that exertional dyspnoea is the main symptom of UAO, but cough remains a common symptom.

Intravenous acetaminophen for the treatment of intrapartum fever and resolution of fetal tachycardia: a novel use for an old medication.

This case series demonstrates a potential new role for the use of intravenous (IV) acetaminophen. The authors reviewed two cases, whereby patients that developed intrapartum fever leading to fetal tachycardia were effectively treated with IV acetaminophen, leading to rapid reduction of maternal temperature and resolution of fetal tachycardia. Both patients had an uncomplicated vaginal delivery of healthy neonates. Intravenous acetaminophen, with its increased bioavailability and more rapid onset of action, may have benefit in the intrapartum setting by reducing adverse neonatal and maternal outcomes associated with febrile morbidity.

Gene delivery to the spinal cord using MRI-guided focused ultrasound.

Non-invasive gene delivery across the blood-spinal cord barrier (BSCB) remains a challenge for treatment of spinal cord injury and disease. Here, we demonstrate the use of magnetic resonance image-guided focused ultrasound (MRIgFUS) to mediate non-surgical gene delivery to the spinal cord using self-complementary adeno-associated virus serotype 9 (scAAV9). scAAV9 encoding green fluorescent protein (GFP) was injected intravenously in rats at three dosages: 4 × 10(8), 2 × 10(9) and 7 × 10(9) vector genomes per gram (VG g(-1)). MRIgFUS allowed for transient, targeted permeabilization of the BSCB through the interaction of focused ultrasound (FUS) with systemically injected Definity lipid-shelled microbubbles. Viral delivery at 2 × 10(9) and 7 × 10(9) VG g(-1) leads to robust GFP expression in FUS-targeted regions of the spinal cord. At a dose of 2 × 10(9) VG g(-1), GFP expression was found in 36% of oligodendrocytes, and in 87% of neurons in FUS-treated areas. FUS applications to the spinal cord could address a long-term goal of gene therapy: delivering vectors from the circulation to diseased areas in a non-invasive manner.

Colonoscopy after spinal cord injury: a case-control study.

DESIGN: An age- and gender-matched case-control study. OBJECTIVE: To compare colonoscopy after spinal cord injury (SCI) with the general population in terms of indications, bowel preparation, technical success and disease detection. SETTING: Victoria, Australia. METHODS: Consecutive SCI colonoscopies between January 1998 and February 2013 were compared with a randomly selected age- and gender-matched control group. Injury level, indication for procedure and demographics were collected. Outcome measures included quality of bowel preparation, completion rates, procedural duration and benign and malignant disease detection. RESULTS: A total of 440 colonoscopies were assessed, comprising 148 SCI patients and 292 age- and gender-matched controls. Both the groups were of similar age (54.7 years vs 54.5 years, P=0.906) and comprised predominantly males (87.1% vs 86.3%, P=0.919). SCI colonoscopies were more often performed to investigate abnormalities (85.1% vs 58.2%, P<0.001) than for screening or surveillance (18.2% vs 40.8%, P<0.001). Unsatisfactory bowel preparation was recorded more often in the SCI group (36.0% vs 13.0%, P<0.001) and completion rates were lower (75.7% vs 93.1%, P<0.001). Overall disease detection was lower in the SCI group (45.3% vs 59.6%, P<0.006). The polyp detection rate was lower for SCI (11.4% vs 25.3%, P=0.001). The rate of diagnosis of malignancy was equivalent (2.7% vs 3.0%, P=0.904). CONCLUSION: SCI patients have the same risk of malignancy as the general population and are less likely to undergo screening colonoscopy. Colonoscopy is then limited by poor bowel preparation and lower completion rates with a subsequent lower polyp detection rate.

Role of endoplasmic reticulum stress induction by the plant toxin, persin, in overcoming resistance to the apoptotic effects of tamoxifen in human breast cancer cells.

BACKGROUND: Persin is a plant toxin that displays synergistic cytotoxicity with tamoxifen in human breast cancer cell lines. Here, we examined the ability of persin to circumvent tamoxifen resistance and delineated the intracellular signalling pathways involved. METHODS: The induction of apoptosis in tamoxifen-resistant and -sensitive breast cancer cells was measured by flow cytometry following treatment with persin±tamoxifen. Markers of endoplasmic reticulum stress (ERS) were analysed following treatment, and their causal role in mediating persin-induced apoptosis was determined using chemical inhibitors and RNA interference. RESULTS: Cells that were resistant to an apoptotic concentration of tamoxifen maintained an apoptotic response to persin. Persin-induced apoptosis was associated with an increase in markers of ERS, that is, CHOP expression and XBP-1 splicing and was decreased by CHOP siRNA. The CASP-4 inhibitor Z-YVAD-FMK markedly inhibited persin-induced apoptosis in both tamoxifen-sensitive and -resistant cells. CONCLUSION: The cytotoxic effects of persin are CASP-4 dependent and mediated by CHOP-dependent and -independent ERS signalling cascades. Increased ERS signalling contributes to persin-induced reversal of tamoxifen resistance.

Vestibular function after vestibular neuritis.

OBJECTIVE: To measure horizontal semicircular canal function over days, weeks, and months after an acute attack of vestibular neuritis. DESIGN: The video head impulse test (vHIT) was used to measure the eye movement response to small unpredictable passive head turns at intervals after the attack. STUDY SAMPLE: Two patients diagnosed with acute right unilateral vestibular neuritis. RESULTS: There was full restoration of horizontal canal function in one patient (A) as shown by the return of the slow phase eye velocity response to unpredictable head turns, while in the other patient (B) there was little or no recovery of horizontal canal function. Instead this second patient generated covert saccades during head turns. CONCLUSION: Despite the objective evidence of their very different recovery patterns, both patients reported, at the final test, being happy and feeling well recovered, even though in one of the patients there was clear absence of horizontal canal function. The results indicate covert saccades seem a successful way of compensating for loss of horizontal canal function after unilateral vestibular neuritis. Factors other than recovery of the slow phase eye velocity are significant for patient recovery.

Rapid generation of region specific probes by chromosome microdissection and their application.

The strategy presented here to identify unequivocally cryptic chromosomal rearrangements has relevance to both prenatal and postnatal cytogenetic analysis as well as the analysis of tumour-associated chromosome rearrangements. Microdissection and in vitro amplification of specific chromosomal regions are performed, followed by labelling for fluorescent in situ hybridization (FISH) to normal metaphase chromosomes (Micro-FISH). Micro-FISH probes have been used successfully to determine the derivation of chromosome segments unidentifiable by standard chromosome banding analysis. Micro-FISH probes (created in less than 24 hours) now make it possible to identify explicitly the chromosome constitution of virtually all cytologically visible chromosome rearrangements.

Mass screening of rice mutant populations at low CO2 for identification of lowered photorespiration and respiration rates.

Introduction: Identifying rice (Oryza sativa) germplasm with improved efficiency of primary metabolism is of utmost importance in order to increase yields. One such approach can be attained through screening genetically diverse populations under altered environmental conditions. Growth or treatment under low carbon dioxide (CO2) concentrations can be used as a means of revealing altered leaf photorespiration, respiration and other metabolic variants. Methods: We developed a pipeline for very high throughput treatment of gamma- and ethyl methanesulfonate- (EMS) induced mutant populations of IR64 rice seedlings at very low CO2 for 7 days. 1050 seedlings per batch at 5th leaf stage were exposed to 60 ppm CO2 for the first day and 30 ppm for the remaining three days. Following this, putative candidates were identified by measuring chlorophyll depletion using SPAD. Screening results showed a distinct difference between the mutants and the WTs. Results and discussion: The mean chlorophyll loss in WTs ranged from 65% to 11% respectively, whereas in the mutant lines chlorophyll loss ranged from 0 to 100%, suggesting considerable phenotypic variation. Rice mutants with a reduced chlorophyll reduction (<10%) were identified as 'Chlorophyll retention mutants' (CRMs) under low CO2 stress. In total, 1909 mutant lines (14,000 seedlings) were screened for chlorophyll content under 30 ppm CO2, with 26 lines selected for detailed screening. These 26 putative candidates were self-seeded to produce an M5 generation, used to determine the genetic control of the altered response to low CO2. Gas exchange of light and CO2 response revealed that there were significant variations among photosynthetic properties in two selected rice mutants. The CO2 compensation points in the absence of photorespiration and leaf respiration rates were lower than the WTs and anatomical analyses showed that CRM 29 had improved mesophyll cell area. We propose that this approach is useful for generating new material for breeding rice with improved primary metabolism.

Fabry disease in unselected patients with TIA or stroke: population-based study.

BACKGROUND: Fabry disease (FD) is an X-linked lysosomal storage disorder frequently associated with cerebrovascular disease. In recent years, the prevalence of FD has been reported to be up to 4% in cryptogenic young stroke patients. However, there have been no population-based studies in unselected patients with transient ischaemic attack (TIA) or stroke across the full range of ages. METHODS: We determined the prevalence of FD mutations in consecutive patients from a population-based study of acute TIA or ischaemic stroke (Oxford Vascular Study). Analysis included amplifying of the α-galactosidase A gene by polymerase chain reaction, denaturing high-performance liquid chromatography (dHPLC) analysis and sequencing using standard automated sequencing protocols [Mutation Surveyor software (Softgenetics)] where the dHPLC indicated a possible mutation. RESULTS: Samples of 1046 consecutive patients (52% women; mean age 73.2 years; 15% age <60 years; 572 stroke; 474 TIA) were tested. No patient had a known gene mutation causing FD, giving an upper 95% confidence interval around the estimated frequency of 0.35% overall and 2.37% in the 154 patients aged under 60 years. However, in 5 (0.48%) samples, a known polymorphism or sequence variation in the gene was identified that can be associated with lower than normal enzyme activity in plasma without causing the full clinical manifestation of FD. CONCLUSIONS: Fabry disease is rare in an unselected group of UK patients with TIA or stroke. Larger studies in unselected younger patients with cryptogenic stroke are required to determine whether routine screening is justified in this group.

Does unilateral utricular dysfunction cause horizontal spontaneous nystagmus?

The presence of spontaneous nystagmus in darkness with a strong horizontal component has been taken to indicate that there is asymmetrical function of the horizontal semicircular canals. If this horizontal spontaneous nystagmus can be suppressed by vision, then it is regarded as due to peripheral horizontal canal dysfunction. However, we report evidence from one patient (61-year-old male), who visited the MSA ENT Clinic, Cassino (FR) Italy, reporting acute, severe vertigo, postural unsteadiness, nausea and vomiting associated with right sudden hearing loss. The patient received instrumental audiovestibular testing to obtain objective measurements of his inner-ear receptors. At the time of the attack, the patient showed spontaneous nystagmus, mainly with horizontal and vertical components (3D infrared video-oculography). Video head-impulse tests of dynamic horizontal canal function showed that the functional status of both horizontal canals was within the normal range. Cervical VEMPs to 500 Hz bone-conducted vibration at Fz showed normal results; ocular VEMPs to the same stimulus showed a reduced n10 amplitude beneath the left eye, corresponding to the right ear. For this reason, the patient was diagnosed as having right unilateral selective utricular macula lesion due to labyrinthitis. There is considerable evidence of convergence of neural input from the otoliths onto horizontal canal neurons in the vestibular nuclei. The firing of such neurons could reflect either asymmetrical horizontal canal function or asymmetrical utricular function. The problem with this patient was not due to asymmetrical horizontal canal function, but only to asymmetrical utricular function, demonstrated by the results of the oVEMP test.

Does intra-abdominal desmoid disease affect patients with an ileal pouch differently than those with an ileorectal anastomosis?

BACKGROUND: Nobody has analyzed the sequelae of desmoids according to the type of surgery that precipitated them. OBJECTIVE: This study aims to determine whether the clinical effects of abdominal desmoids would be worse in patients with restorative proctocolectomy than in patients with ileorectal anastomosis. DESIGN: This is a retrospective, database study. PATIENTS: Included were patients with familial adenomatous polyposis who had undergone proctocolectomy with IPAA or colectomy and ileorectal anastomosis, and subsequently developed an intra-abdominal desmoid tumor. MAIN OUTCOME MEASURES: The primary outcome measures were the clinical course of the desmoids; morbidity, and the requirement for stoma. RESULTS: There were 86 patients: 49 had restorative proctocolectomy and 37 had ileorectal anastomosis. Patient demographics were similar. Average follow-up was 9.8 years (range, 2.7-23.8) and 16.3 years (range, 2.3 - 42.9). Treatment of the desmoids included surgery (64.4% vs 65.6%), medical therapy (69.4% vs 59.5%), chemotherapy (36.2% vs 30.0%), and radiotherapy (4.5% vs 10.0%), and was the same for each group. The overall complication rate of desmoids was similar, approaching 70%. The risk of individual complications was also similar (bleeding (2.0% vs 0.0%), fistula (10.2% vs 13.5%), bowel obstruction (32.7% vs 48.6%), pain (34.7% vs 21.6%), and death related to desmoid tumors (2.0% vs 10.8%)); 38.8% of the restorative proctocolectomy group and 51.4% the ileorectal group had surgery for desmoid tumor complications (P = .21), and 22.4% and 22.2% of patients ultimately had permanent stomas. LIMITATIONS: This study was limited by the relatively small numbers of patients. CONCLUSION: The morbidity associated with desmoid tumors has not been shown to differ, whether they arise after restorative proctocolectomy or ileorectal anastomosis.

Respiration and protein synthesis in Escherichia coli membrane-envelope fragments. I. Oxidative activities with soluble substrates.

This paper describes experiments conducted with membranous and soluble fractions obtained from Escherichia coli that had been grown on succinate, malate, or enriched glucose media. Oxidase and dehydrogenase activities were studied with the following substrates: nicotinamide adenine dinucleotide, reduced form (NADH), nicotinamide adenine dinucleotide phosphate, reduced form (NADPH), succinate, malate, isocitrate, glutamate, pyruvate, and alpha-ketoglutarate. Respiration was virtually insensitive to poisons that are commonly used to inhibit mitochondrial systems, namely, rotenone, antimycin, and azide. Succinate dehydrogenase and NADH, NADPH, and succinate oxidases were primarily membrane-bound whereas malate, isocitrate, and NADH dehydrogenases were predominantly soluble. It was observed that E. coli malate dehydrogenase could be assayed with the dye 2,6-dichlorophenol indophenol, but that porcine malate dehydrogenase activity could not be assayed, even in the presence of E. coli extracts. The characteristics of E. coli NADH dehydrogenase were shown to be markedly different from those of a mammalian enzyme. The enzyme activities for oxidation of Krebs cycle intermediates (malate, succinate, isocitrate) did not appear to be under coordinate genetic control.

Respiration and protein synthesis in Escherichia coli membrane-envelope fragments. II. Effects of fatty acids and albumin on respiration.

Fatty acids inhibited the ability of Escherichia coli membrane-envelope fragments to catalyze the oxidation of succinate and nicotinamide adenine dinucleotide, reduced form (NADH) and also inhibited the response of the Clark oxygen electrode to nonenzymatic oxygen uptake. In all cases, unsaturated fatty acids were much more inhibitory than saturated fatty acids. Albumin afforded complete protection from inhibition in the nonenzymatic oxygen-uptake experiments but only partial protection for the respiratory activities of the membrane fragments. The succinoxidase activity was totally inhibited by bovine serum albumin at concentrations that inhibited succinate dehydrogenase only slightly and NADH oxidase not at all. The E. coli acellular preparation showed no dehydrogenase or oxidase activity for any of the fatty acids under a variety of conditions. These conditions included variations of pH, concentration of fatty acids, and the presence or absence of albumin, CoA, ATP, NAD, cysteine, succinate, and carnitine. It thus appears that E. coli grown in the absence of fatty acid can not use fatty acids as an energy source.

Respiration and protein synthesis in Escherichia coli membrane-envelope fragments. VI. Solubilization and characterization of the electron transport chain.

Membranes obtained from Escherichia coli have been solubilized with deoxycholate. The solubilized dehydrogenases and cytochromes are not sedimented at 105,000 g. These components readily penetrate the "included space" of Sepharose 4B (Pharmacia Fine Chemicals Inc., Uppsala, Sweden) and polyacrylamide gels and have been fractionated on the basis of molecular size. Solubilization destroys nicotinamide adenine dinucleotide, reduced form (NADH) oxidase and D-lactate oxidase activities, but leaves an appreciable part of the original succinoxidase activity intact. Evidence for a succinate dehydrogenase-cytochrome b(1) complex is given. Menadione added to the solubilized preparation does not elicit NADH oxidase activity nor stimulate the existing succinoxidase activity, but does provoke an active D-lactate oxidase activity. This D-lactate oxidase activity, however, does not use cytochromes and is not sensitive to cyanide.

Molecular and biological properties of a macrophage colony-stimulating factor from mouse yolk sacs.

A colony-stimulating factor (M-CSF) has been partially purified and concentrated from mouse yolk sac-conditioned medium (YSCM). M-CSF appeared to preferentially stimulate CBA bone marrow granulocyte-macrophage progenitor cells (GM-CFC) to differentiate to form macrophage colonies in semisolid agar cultures. By comparison, colony-stimulating factor (GM-CSF) from mouse lung-conditioned medium (MLCM) stimulated the formation of granulocytic, mixed granulocytic-macrophage, and pure macrophage colonies. Mixing experiments indicated that both M-CSF and GM-CSF stimulated all of the GM-CFC but that the smaller CFC were more sensitive to GM-CSF and that the larger CFC were more sensitive to M-CSF. Almost all developing "clones" stimulated initially with M-CSF continued to develop when transferred to cultures containing GM-CSF. In the converse situation, only 50% of GM-CSF prestimulated "clones" survived when transferred to cultures containing M-CSF. All clones initially stimulated by M-CSF or transferred to cultures stimulated by M-CSF contained macrophages after 7 days of culture. These results suggest that there is a population of cells (GM-CFC) that are capable of differentiating to form both granulocytes and macrophages, but, once these cells are activated by a specific CSF (e.g. M-CSF), they are committed to a particular differentiation pathway. The pattern of CFC differentiation was not directly related to the rate of proliferation: cultures maximally stimulated by M-CSF produced mostly macrophage colonies, but the presence of small amounts of GM-CSF produced granulocytic cells in 30% of the colonies. Gel filtration, polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, and affinity chromatography with concanavalin A-Sepharose indicated that M-CSF from yolk sacs was a glycoprotein with an apparent molecular weight of 60,000. There was some heterogeneity of the carbohydrate portion of the molecule as evidenced by chromatography on concanavalin A-Sepharose.

Respiration and protein synthesis in Escherichia coli membrane-envelope fragments. IV. Chemical and cytological characterization and biosynthetic capabilities of fragments obtained by mild procedures.

Membrane-envelope fragments have been isolated from Escherichia coli by comparatively mild techniques. The use of DNAase, RNAase, detergents, sonication, lysozyme, and ethylenediaminetetraacetate were avoided in the belief that rather delicate, but metabolically important, associations may exist between the plasma membrane and various cytoplasmic components. The membrane-envelope fragments have been characterized in terms of their content of major chemical components as well as their electron microscope appearance. Fractions containing membrane-envelope fragments were found to possess appreciable DNA- and protein-synthesizing activities. The fragments were rich in membrane content as determined by reduced nicotinamide adenine dinucleotide (NADH) oxidase activity and deficient in soluble components as measured by NADH dehydrogenase activity. The particulate fraction obtained between 20,000 g and 105,000 g and usually considered a ribosomal fraction was rich in membrane content and had a relatively high capacity for DNA synthesis. Envelope fragments sedimenting at 20,000 g attained very high levels of incorporation of amino acids into protein.