Fatty Acid Availability Sets Cell Envelope Capacity and Dictates Microbial Cell Size.

Nutrients-and by extension biosynthetic capacity-positively impact cell size in organisms throughout the tree of life. In bacteria, cell size is reduced 3-fold in response to nutrient starvation or accumulation of the alarmone ppGpp, a global inhibitor of biosynthesis. However, whether biosynthetic capacity as a whole determines cell size or whether particular anabolic pathways are more important than others remains an open question. Here we identify fatty acid synthesis as the primary biosynthetic determinant of Escherichia coli size and present evidence supporting a similar role for fatty acids as a positive determinant of size in the Gram-positive bacterium Bacillus subtilis and the single-celled eukaryote Saccharomyces cerevisiae. Altering fatty acid synthesis recapitulated the impact of altering nutrients on cell size and morphology, whereas defects in other biosynthetic pathways had either a negligible or fatty-acid-dependent effect on size. Together, our findings support a novel "outside-in" model in which fatty acid availability sets cell envelope capacity, which in turn dictates cell size. In the absence of ppGpp, limiting fatty acid synthesis leads to cell lysis, supporting a role for ppGpp as a linchpin linking expansion of cytoplasmic volume to the growth of the cell envelope to preserve cellular integrity.

Cornual wedge resection for interstitial pregnancy and postoperative outcome.

INTRODUCTION: Traditionally, interstitial pregnancies were treated with cornual resection or hysterectomy via laparotomy. However, increasingly, interstitial pregnancies are treated with laparoscopic cornuotomy, ie, removal of ectopic pregnancy tissue with preservation of uterine architecture. Although this technique may increase the incidence of persistent and recurrent interstitial pregnancy, it can potentially maintain patient fertility and decrease their risk for future uterine rupture. In a case series of patients with interstitial pregnancies treated with cornual wedge resection, we examined fertility outcomes, rates of subsequent uterine rupture, and rates of persistent or recurrent interstitial pregnancy. MATERIALS AND METHODS: We conducted a retrospective medical record review of cases (n = 29) of cornual wedge resection for interstitial pregnancy, performed between 1992 and 2013 at one hospital. RESULTS: Of the 29 cases, two later presented with uterine rupture; one, who also had a prior wedge resection, was found with scar dehiscence during a subsequent caesarean section. The incidence of subsequent uterine rupture and dehiscence was 30%. There were no cases of persistent ectopic pregnancy or recurrent interstitial pregnancy. Most (71.4%) patients who were trying to conceive achieved subsequent pregnancy. DISCUSSION: There is debate regarding the recommended surgical technique to treat interstitial pregnancies; cornual resection and cornuotomy are both important considerations. Choice of the technique employed continues to require careful consideration.

Time-varying surface electromyography topography as a prognostic tool for chronic low back pain rehabilitation.

BACKGROUND CONTEXT: Nonsurgical rehabilitation therapy is a commonly used strategy to treat chronic low back pain (LBP). The selection of the most appropriate therapeutic options is still a big challenge in clinical practices. Surface electromyography (sEMG) topography has been proposed to be an objective assessment of LBP rehabilitation. The quantitative analysis of dynamic sEMG would provide an objective tool of prognosis for LBP rehabilitation. PURPOSE: To evaluate the prognostic value of quantitative sEMG topographic analysis and to verify the accuracy of the performance of proposed time-varying topographic parameters for identifying the patients who have better response toward the rehabilitation program. STUDY DESIGN: A retrospective study of consecutive patients. PATIENT SAMPLE: Thirty-eight patients with chronic nonspecific LBP and 43 healthy subjects. OUTCOME MEASURES: The accuracy of the time-varying quantitative sEMG topographic analysis for monitoring LBP rehabilitation progress was determined by calculating the corresponding receiver-operating characteristic (ROC) curves. Physiologic measure was the sEMG during lumbar flexion and extension. METHODS: Patients who suffered from chronic nonspecific LBP without the history of back surgery and any medical conditions causing acute exacerbation of LBP during the clinical test were enlisted to perform the clinical test during the 12-week physiotherapy (PT) treatment. Low back pain patients were classified into two groups: "responding" and "nonresponding" based on the clinical assessment. The responding group referred to the LBP patients who began to recover after the PT treatment, whereas the nonresponding group referred to some LBP patients who did not recover or got worse after the treatment. The results of the time-varying analysis in the responding group were compared with those in the nonresponding group. In addition, the accuracy of the analysis was analyzed through ROC curves. RESULTS: The time-varying analysis showed discrepancies in the root-mean-square difference (RMSD) parameters between the responding and nonresponding groups. The relative area (RA) and relative width (RW) of RMSD at flexion and extension in the responding group were significantly lower than those in the nonresponding group (p<.05). The areas under the ROC curve of RA and RW of RMSD at flexion and extension were greater than 0.7 and were statistically significant. CONCLUSIONS: The quantitative time-varying analysis of sEMG topography showed significant difference between the healthy and LBP groups. The discrepancies in quantitative dynamic sEMG topography of LBP group from normal group, in terms of RA and RW of RMSD at flexion and extension, were able to identify those LBP subjects who would respond to a conservative rehabilitation program focused on functional restoration of lumbar muscle.

GTP dysregulation in Bacillus subtilis cells lacking (p)ppGpp results in phenotypic amino acid auxotrophy and failure to adapt to nutrient downshift and regulate biosynthesis genes.

The nucleotide (p)ppGpp inhibits GTP biosynthesis in the Gram-positive bacterium Bacillus subtilis. Here we examined how this regulation allows cells to grow in the absence of amino acids. We showed that B. subtilis cells lacking (p)ppGpp, due to either deletions or point mutations in all three (p)ppGpp synthetase genes, yjbM, ywaC, and relA, strongly require supplementation of leucine, isoleucine, valine, methionine, and threonine and modestly require three additional amino acids. This polyauxotrophy is rescued by reducing GTP levels. Reduction of GTP levels activates transcription of genes responsible for the biosynthesis of the five strongly required amino acids by inactivating the transcription factor CodY, which represses the ybgE, ilvD, ilvBHC-leuABCD, ilvA, ywaA, and hom-thrCB operons, and by a CodY-independent activation of transcription of the ilvA, ywaA, hom-thrCB, and metE operons. Interestingly, providing the eight required amino acids does not allow for colony formation of (p)ppGpp(0) cells when transitioning from amino acid-replete medium to amino acid-limiting medium, and we found that this is due to an additional role that (p)ppGpp plays in protecting cells during nutrient downshifts. We conclude that (p)ppGpp allows adaptation to amino acid limitation by a combined effect of preventing death during metabolic transitions and sustaining growth by activating amino acid biosynthesis. This ability of (p)ppGpp to integrate a general stress response with a targeted reprogramming of gene regulation allows appropriate adaptation and is likely conserved among diverse bacteria.

Comparison of HER2 status by fluorescence in situ hybridization and immunohistochemistry to predict benefit from dose escalation of adjuvant doxorubicin-based therapy in node-positive breast cancer patients.

PURPOSE: HER2 is a clinically important tumor marker in breast cancer; however, there is controversy regarding which method reliably measures HER2 status. We compared three HER2 laboratory methods: immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR), to predict disease-free survival (DFS) and overall survival (OS) after adjuvant doxorubicin-based therapy in node-positive breast cancer patients. METHODS: This is a Cancer and Leukemia Group B (CALGB) study, using 524 tumor blocks collected from breast cancer patients registered to clinical trial CALGB 8541. IHC employed CB11 and AO-11-854 monoclonal antibodies; FISH used PathVysion HER2 DNA Probe kit; PCR utilized differential PCR (D-PCR) methodology. RESULTS: Cases HER2 positive by IHC, FISH and D-PCR were 24%, 17%, and 18%, respectively. FISH and IHC were clearly related (kappa = 64.8%). All three methods demonstrated a similar relationship for DFS and OS. By any method, for patients with HER2-negative tumors, there was little or no effect of dose of adjuvant doxorubicin-based therapy. For patients with HER2-positive tumors, all three methods predicted a benefit from dose-intense (high-dose) compared with low- or moderate-dose adjuvant doxorubicin-based therapy. CONCLUSION: FISH is a reliable method to predict clinical outcome following adjuvant doxorubicin-based therapy for stage II breast cancer patients. There is a moderate level of concordance among the three methods (IHC, FISH, PCR). None of the methods is clearly superior. Although IHC-positive/FISH-positive tumors yielded the greatest interaction with dose of therapy in predicting outcome, no combination of assays tested was statistically superior.