Structure-function relationships of TMJ lateral capsule-ligament complex

The human temporomandibular joint (TMJ) lateral capsule ligament (LCL) complex is debated as a fibrous capsule with distinct ligaments or ligamentous thickening, necessitating further evaluation of the complex and its role in TMJ anatomy and mechanics. This study explores the ultrastructural arrangement, biomechanical tensile properties, and biochemical composition of the human LCL complex including region-specific differences to explore the presence of a distinct temporomandibular ligament and sex-specific differences to inform evaluations of potential etiological mechanisms. LCL complex ultrastructural arrangement, biomechanical properties, and biochemical composition were determined using cadaveric samples. Statistical modeling assessed sex- and region-specific effects on LCL complex tissue properties. Collagen fiber coherency, collagen fiber bundle size, and elastin fiber count did not differ between sexes, but females trended higher in elastin fiber count. LCL complex water and sGAG content did not differ between sexes or regions, but collagen content was higher in the anterior region (311.0 ± 185.6 μg/mg) compared to the posterior region (221.0 ± 124.9 μg/mg) (p = 0.045) across sexes and in males (339.6 ± 170.6 μg/mg) compared to females (204.5 ± 130.7 μg/mg) (p = 0.006) across regions. Anterior failure stress (1.1 ± 0.7 MPa) was larger than posterior failure stress (0.6 ± 0.4 MPa) (p = 0.024). Regional differences confirm the presence of a mechanically and compositionally distinct temporomandibular ligament. Baseline sex-specific differences are critical for etiological investigations of sex disparities in TMJ disorders. These results have important biomechanical and clinical ramifications, providing critical baseline tissue material properties, informing the development of TMJ musculoskeletal models, and identifying new areas for etiologic investigations for temporomandibular disorders.

Regional variation in composition and antimicrobial activity of US propolis against Paenibacillus larvae and Ascosphaera apis

Propolis is a substance derived from antimicrobial plant resins that honey bees use in the construction of their nests. Propolis use in the hive is an important component of honey bee social immunity and confers a number of positive physiological benefits to bees. The benefits that bees derive from resins are mostly due to their antimicrobial properties, but it is unknown how the diversity of antimicrobial activities among resins might impact bee health. In our previous work, we found that resins from different North American Populus spp. differed in their ability to inhibit in vitro growth of the bee bacterial pathogen Paenibacillus larvae. The goal of our current work was to characterize the antimicrobial activity of propolis from 12 climatically diverse regions across the US against the bee pathogens P. larvae and Ascosphaera apis and compare the metabolite profiles among those samples using LC-MS-based metabolomic methods. Samples differed greatly in their ability to inhibit both bacterial and fungal growth in vitro, but propolis from Nevada, Texas, and California displayed high activity against both pathogens. Interestingly, propolis from Georgia, New York, Louisiana, and Minnesota were active against A. apis, but not very active against P. larvae. Metabolomic analysis of regional propolis samples revealed that each sample was compositionally distinct, and LC-FTMS profiles from each sample contained a unique number of shared and exclusive peaks. Propolis from Aspen, CO, Tuscon, AZ, and Raleigh, NC, contained relatively large numbers of exclusive peaks, which may indicate that these samples originated from relatively unique botanical sources. This is the first study to characterize how the diversity of bee preferred resinous plants in the US may affect bee health, and could guide future studies on the therapeutic potential of propolis for bees.

Abstract P3-08-01: Cognitive impairment and cortical network dysfunction following chemotherapy

A common complaint of cancer patients is the experience of cognitive difficulty during and after chemotherapy. However, the mechanisms through which this occurs are still unknown. We hypothesized that chemotherapy-induced cognitive impairment may result from dysfunction in large-scale brain networks, particularly those involved in attentional control. These networks are evident when measuring task-based brain activity during attention-demanding tasks, but can also be studied using resting state functional connectivity magnetic resonance imaging (rs-fcMRI). In rs-fcMRI, connectivity between brain regions is measured using data collected while participants lie awake in the magnet with their eyes open, but performing no task. It reliably distinguishes known sensory, motor, and executive networks based on connectivity patterns. These data complement information about structural (white matter) connectivity obtained using diffusion tensor imaging (DTI).

Here we report a case-control study of women with a history of triple negative breast cancer (BrCa) who completed standard adjuvant chemotherapy within two years of study entry. The cases (n = 15) were defined as women who reported cognitive impairment by the Cognitive Failures Questionnaire and controls (n = 13) were women who did not report cognitive impairment. All participants eligible for MRI investigation underwent rs-fcMRI and DTI on a Siemens 3T TIM Trio scanner. DTI parameters measured included Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD), and Axial Diffusivity.

The study was conducted in its entirety at Washington University in St. Louis School of Medicine. Institutional review board approval was obtained prior to recruitment. The mean age of cases was 53.1 years and controls 51.6 years; all were diagnosed with invasive ductal or lobular BrCa.

For each participant, we extracted the timecourse of brain activity for regions of interest in frontoparietal and cingularopercular control systems, measured indirectly via blood oxygenation level dependent (BOLD) contrast, from the MRI scans, and additional regions of interest distributed across the brain. We excluded scans that showed motion artifact. Pairwise connectivity was calculated using Pearson correlation between all regions of interest; we also used these regions in seed-based analyses. We compared the strength of rs-fcMRI-defined network connections between the two groups and used nonparametric permutation tests to calculate statistical significance.

We found significant changes within several regions of the frontoparietal attention network, such that patients reporting greater cognitive difficulty showed weaker neural connectivity. In addition, DTI analyses revealed different patterns of anatomical connectivity between groups, including reduced FA (p<0.03) and increased MD and RD (p<0.02), both of which have been shown to be signatures of brain change in demyelinating disease.

Together our results suggest that standard therapeutic levels of chemotherapy for BrCa patients may result in structural and functional connectivity alterations in the brain networks supporting executive attention, which in turn may be a contributing factor in cognitive difficulty.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-08-01.

Involvement of Jak2 tyrosine phosphorylation in Bcr-Abl transformation

We have previously reported that the Jak2 tyrosine kinase but not Jak1 is tyrosine phosphorylated in the absence of IL-3 in Bcr-Abl positive M3.16 cells, which are rendered IL-3 independent by BCR-ABL gene expression. We have explored the involvement of Jak2 tyrosine phosphorylation in Bcr-Abl oncogenic effects. Our results indicate that Jak2 became tyrosine-phosphorylated in a number of cell lines expressing Bcr-Abl, when maintained in medium lacking IL-3, whereas Bcr-Abl negative cells lacked Jak2 tyrosine phosphorylation. Jak2 was poorly tyrosine-phosphorylated in cells expressing the SH2 deletion mutant of Bcr-Abl compared to either wild-type Bcr-Abl or its SH3 deletion mutant. Moreover, tyrosine phosphorylation of Jak2 by Bcr-Abl was inhibited by the Abl tyrosine kinase inhibitor, STI 571, in a dose-dependent manner. This inhibition of Bcr-Abl kinase by the drug did not interfere with the ability of Jak2 and Bcr-Abl to form a complex. Studies with deletion mutants of Bcr-Abl indicated that the C-terminal domain of Abl within Bcr-Abl was involved in complex formation with Jak2. Similarly, GST-Abl pull-down assays confirmed the strong binding to Jak2 by the C-terminus of Abl. Jak2 peptide substrate studies indicated that the Bcr-Abl and Abl tyrosine kinases specifically phosphorylated Y1007 of Jak2 but only poorly phosphorylated Y1008. Phosphorylation of Y1007 of Jak2 is known to be critical for its tyrosine kinase activation. Tyrosine residue 1007 of Jak2 was phosphorylated in 32Dp210 cells as measured by Western blotting with a phosphotyrosine 1007 sequence-specific antibody. A kinase-inactive Jak2 mutant blocked the colony forming ability of K562 cells. Tumor formation of K562 cells in nude mice was similarly inhibited by this kinase-inactive Jak2 mutant. This inhibition was independent of Stat5 tyrosine phosphorylation. Furthermore, tyrosine-phosphorylated Jak2 was detected in blood cells from CML patients in blast crisis but not in a normal marrow sample. In summary, these findings provide strong evidence that the Jak2 tyrosine kinase is a critical factor in Bcr-Abl malignant transformation.

Transformation of myeloid leukemia cells to cytokine independence by Bcr-Abl is suppressed by kinase-defective Hck

Bcr-Abl is the constitutively active protein-tyrosine kinase expressed as a result of the Philadelphia translocation in chronic myelogenous leukemia. Bcr-Abl is coupled to many of the same signaling pathways normally regulated by hematopoietic cytokines. Recent work shows that Hck, a member of the Src tyrosine kinase family with myeloid-restricted expression, associates with and is activated by Bcr-Abl. Here we investigated the mechanism of Hck interaction with Bcr-Abl and the requirement for Hck activation in Bcr-Abl transformation signaling. Binding studies demonstrated that the Hck SH3 and SH2 domains are sufficient for interaction with Bcr-Abl in vitro. Hck binding localizes to the Abl SH2, SH3, and kinase domains as well as the distal portion of the C-terminal tail. To address the requirement for endogenous Src family kinase activation in Bcr-Abl signaling, a kinase-defective mutant of Hck was stably expressed in the cytokine-dependent myeloid leukemia cell line DAGM. Kinase-defective Hck dramatically suppressed Bcr-Abl-induced outgrowth of these cells in the absence of cytokine compared with a control cell line expressing beta-galactosidase. In contrast, kinase-defective Hck did not affect cell proliferation in response to interleukin-3, suggesting that the effect is specific for Bcr-Abl. These data show that Hck interacts with Bcr-Abl through a complex mechanism involving kinase-dependent and -independent components and that interaction with Hck or other Src family members is essential for transformation signaling by Bcr-Abl.

Control of myeloid differentiation and survival by Stats

Hematopoiesis involves a complex array of growth factors that regulate the survival and proliferation of immature progenitors, influence differentiation commitment, and modulate end-stage cell functions. This mini-review is focused on the role of Stat activation in the development of myeloid cells in response to hematopoietic cytokines. Much of the evidence implicating Stats in these cellular processes comes from studies of mutant cytokine receptors selectively uncoupled from Stat activation, dominant-inhibitory Stat mutants, and mice with targeted disruptions of Stat genes. Together these approaches provide strong evidence that Stat activation, particularly of Stat3 and Stat5, plays an important role in myeloid differentiation and survival. Oncogene (2000).

Felbamate-associated fatal acute hepatic necrosis

Thirty-six cases of hepatic toxicity associated with felbamate therapy have been collected by the Food and Drug Administration. Five patients died. We describe a case of massive acute hepatic necrosis and death within 40 days of initiation of felbamate therapy for a generalized tonic-clonic seizure disorder. We describe the clinical and histopathologic features.

A comparison of copper vapor and flashlamp pumped dye lasers in the treatment of facial telangiectasia

METHODS

Twelve adult patients with bilateral facial telangiectasias were treated with two yellow light lasers. A section of each involved area was treated with a copper vapor laser and a similar section in the same patient was treated with the flashlamp pumped dye laser.

RESULTS

Both lasers provided satisfactory clearance at 2 and 6 weeks. Treatment was not painless with either laser; however, no patient needed local or general anesthesia. The time taken to treat equivalent areas was similar for both lasers. Postoperative swelling was greater with the flashlamp pumped dye laser than with the copper vapor laser and the time required for healing was longer with the flash-lamp pumped dye laser.

CONCLUSION

The larger purpuric macules produced post-operatively by the flashlamp pumped dye laser were less cosmetically acceptable to patients when compared with the thin linear crusting produced by the copper vapor laser. Scarring or textural changes were not seen with either laser.

Relative frequency of nosocomial pathogens at a university hospital during the decade 1980 to 1989

BACKGROUND

We compared the relative frequency of pathogens isolated from 1985 to 1989 (N = 4358) with those isolated from 1980 to 1984 (N = 5290) in a university hospital to determine trends in the relative importance of pathogens causing nosocomial infection.

METHODS

Our study was based on surveillance data prospectively obtained between 1980 and 1989 from a 600-bed university hospital. Statistically significant trends occurring from 1980 to 1984 to 1985 to 1989 were determined by chi 2 tests with Bonferroni corrections (i.e., p less than [0.05/17]).

RESULTS

Overall an increased frequency of isolation occurred for Candida and other yeasts and for Haemophilus species. A decreased frequency was noted for Proteus species, non-Bacteroides anaerobes, and Serratia species. Comparison of 1985 to 1989 with 1980 to 1984 revealed that the most significant change in nosocomial pathogens was the marked increase in infections with yeast, principally Candida species. Candida and other yeast infections increased 40%, from 7.6% (rank, 5) to 10.6% (rank, 3) of all pathogens isolated. Increases, which occurred in urine, blood, and wound isolates, were especially marked among surgical patients. In addition, a significant increase was noted among blood isolates in the isolation of yeast other than Candida albicans.

CONCLUSIONS

We conclude that Candida and other yeasts are being isolated increasingly as causative agents of nosocomial infection.

Aspiration cytologic, ultrastructural, and DNA cytometric findings of solid and papillary tumor of the pancreas

Solid and papillary epithelial neoplasm of the pancreas (SPENP) is a rare lesion characteristically occurring in young women. By contrast with pancreatic ductal adenocarcinomas, SPENP is a slow-growing tumor that rarely metastasizes or is fatal. The current report describes light and electron microscopic and histochemical findings with DNA flow cytometric analyses of two cases of SPENP. The first patient was a 24-year-old woman; the second, a 72-year-old man. Although SPENP is rare in older men, both patients had characteristic radiographic and light microscopic features of SPENP. Ultrastructural evidence of acinar differentiation was seen in the first patient; the second patient had focal neuroendocrine differentiation. Flow cytometric analysis of the first tumor demonstrated diploid-range DNA content with a 5.8% S-phase fraction (SPF). The DNA cytometric analysis of a biopsy specimen from the second tumor revealed diploid-range DNA content with a 6.1% SPF, although subsequent sampling of the resected tumor showed an aneuploid population with a DNA index of 1.8 and SPF of 2.1%.

Aspiration cytologic, ultrastructural, and DNA cytometric findings of solid and papillary tumor of the pancreas

Solid and papillary epithelial neoplasm of the pancreas (SPENP) is a rare lesion characteristically occurring in young women. By contrast with pancreatic ductal adenocarcinomas, SPENP is a slow-growing tumor that rarely metastasizes or is fatal. The current report describes light and electron microscopic and histochemical findings with DNA flow cytometric analyses of two cases of SPENP. The first patient was a 24-year-old woman; the second, a 72-year-old man. Although SPENP is rare in older men, both patients had characteristic radiographic and light microscopic features of SPENP. Ultrastructural evidence of acinar differentiation was seen in the first patient; the second patient had focal neuroendocrine differentiation. Flow cytometric analysis of the first tumor demonstrated diploid-range DNA content with a 5.8% S-phase fraction (SPF). The DNA cytometric analysis of a biopsy specimen from the second tumor revealed diploid-range DNA content with a 6.1% SPF, although subsequent sampling of the resected tumor showed an aneuploid population with a DNA index of 1.8 and SPF of 2.1%.

Nosocomial infection rate as a function of human immunodeficiency virus type 1 status in hemophiliacs

As part of a prospective cohort study initiated in 1983, the human immunodeficiency virus type 1 (HIV-1) status has been periodically determined for patients with clotting disorders (hemophilia A or B, von Willebrand's disease, miscellaneous). The University of North Carolina Hospitals has conducted comprehensive surveillance for nosocomial infections (NI) using modified Centers for Disease Control criteria since 1980 and entered this information in a computerized data base. Cross-matching of our NI data base and hemophiliac/HIV-1 study data base for the time period 1980-1989 revealed that 13 NI occurred in 11 patients during 659 hospitalizations (5,723 hospital days). NI rates per 100 admissions (per 1,000 hospital days) by HIV-1 status were as follows: HIV-1 negative = 0.91 (1.18), HIV-1 positive pre-AIDS = 1.65 (1.84), and AIDS = 6.67 (6.48). NI occurred with a similar frequency in HIV-1 positive pre-AIDS hemophiliacs and HIV-1 negative hemophiliacs (Fisher's exact test, p greater than 0.10). However, NI occurred more frequently in hemophiliacs with AIDS versus HIV-1 positive or negative hemophiliacs (Fisher's exact test, p less than 0.05). We conclude that HIV-1 infection does not appreciably alter the risk of developing a NI, but that patients who have progressed to AIDS are at significantly increased risk of developing a NI per hospital day or per hospitalization.

Manual ventilation bags as a source for bacterial colonization of intubated patients

A group of 14 intensive care unit (ICU) patients were studied to determine if manual ventilation bags (MVB) could serve as a source of bacterial or fungal pathogens that could colonize the respiratory tract of intubated patients. A total of 51 cultures were simultaneously obtained of patient's sputum, the exterior MVB surface, MVB port, and MVB interior (postexhalation valve). Pathogens colonizing or infecting the respiratory tract of intubated ICU patients were frequently simultaneously present on the exterior surface of the MVB and inside the MVB port used to connect the MVB with the endotracheal tube. In addition, coagulase-negative staphylococci and yeast were frequently present on the exterior surface of the MVB. The interior of the MVB was usually sterile. In three instances pathogens were isolated from the MVB before isolation from the patient's sputum. MVB may serve as a source for colonizing the respiratory tract of intubated ICU patients and/or the hands of medical personnel. The exterior surface and port of MVB should be cleaned of visible debris and disinfected at least once a day.

Infantile fibrosarcoma--a misnomer?

Two cases of congenital or infantile fibrosarcoma are described that were incompletely excised at the time of primary excision and have not recurred or metastasized after 3 years. The tumors were composed of densely cellular spindle cells with a high mitotic index. Immunohistochemical stains were positive for vimentin but negative for desmin and S-100. The tumor cells were grown in vitro, and a karyotype was obtained. Both tumors had normal diploid modal karyotypes. In addition, fragments of the primary tumor from both cases were injected subcutaneously into nude mice; neither tumor could be heterotransplanted. The clinical course and biologic features of these two tumors suggest that congenital or infantile sarcoma does not have the properties of a malignant neoplasm, and thus the designation of these tumors as a sarcoma may be a misnomer.

Post-traumatic changes in, and effect of colloid osmotic pressure on the distribution of body water

The aim of this study was to define the post-traumatic changes in body fluid compartments and to evaluate the effect of plasma colloid osmotic pressure (COP) on the partitioning of body fluid between these compartments. Forty-two measurements of plasma volume (green dye), extracellular volume (bromine), and total body water (deuterium) were done in ten traumatized patients (mean Injury Severity Score, ISS, = 34) and 23 similar control studies were done in eight healthy volunteers who were in stable fluid balance. Interstitial volume, intracellular volume, and blood volume were calculated from measured fluid spaces and hematocrit; COP was directly measured. Studies in volunteers on consecutive days indicated good reproducibility, with coefficients of variation equal to 3.5% for COP, 6.3% for plasma volume, 4.5% for extracellular volume, and 4.9% for total body water. COP values extended over the entire range seen clinically, from 10 to 30 mmHg. Interstitial volume was increased by 55% in patients, but intracellular volume was decreased by 10%. We conclude (1) that posttraumatic peripheral edema resulting from hemodilution is located in the interstitial compartment, with no intracellular space expansion; and (2) that interstitial volume, but not intracellular volume, is closely related to plasma COP.

Plaster-associated Bacillus cereus wound infection. A case report

Plaster of Paris and nonsterile cast padding have previously been implicated in wound infections. The observation of three pin site infections with Bacillus cereus following pin placement and plaster fixation of an open forearm fracture led to an epidemiologic investigation. Two hundred sixty-one bacterial cultures were taken from materials in the Steinmann pin application and plaster fixation procedures. B. cereus with a similar antibiogram and biotype as was identified in the pin site cultures was recovered from three of the 22 (14%) plaster-impregnated gauze rolls and six of seven (81%) tapwater samples. The Bacillus sp contamination rate of plaster when dry or wetted with sterile water or tapwater was 58%, 25% and 40% respectively. All cultures of plaster samples were negative after steam or gas sterilization. These results suggest that the patient may have acquired the infection from the plaster-impregnated gauze wetted in tapwater. In this case, the Steinmann pins may have facilitated infection by guiding the plaster-associated bacteria to the pin insertion site. The use of gas sterilized plaster materials should be considered in certain circumstances.

Risk factor analysis among men referred for possible acquired immune deficiency syndrome

Responses to a lifestyle questionnaire among 13 patients with Kaposi's sarcoma and 18 with an opportunistic infection were compared with those of 29 symptom-free referred individuals. Odds ratios (OR) with 95% confidence limits were calculated as an estimate of risk. Significantly elevated odds ratios (P less than 0.05) were found for cigarette smoking (OR = 3.4), marijuana use (OR = 3.7), nitrite use (OR = 5.5), frequenting bathhouses (OR = 7.6), prior syphilis (OR = 3.4), and fist-rectal sexual practices (OR = 3.5). A response gradient for the risk estimates was found for marijuana use (OR = 2.7 for occasional, OR = 4.3 for frequent use); nitrites (OR = 4.0 for occasional; OR = 6.3 for frequent use); and prior syphilis (OR = 2.9 for one to two previous infections and 9.0 for three or more). We believe the evidence is now sufficient to recommend preventive practices which may reduce the male homosexual's risk for developing acquired immune deficiency syndrome, Kaposi's sarcoma, and/or opportunistic infections. These include cessation of cigarette smoking, marijuana use, and nitrite inhalation; reduction in number of anonymous sexual partners to decrease risk of sexually transmitted diseases; and avoidance of fisting.

Increased recovery of Aspergillus flavus from respiratory specimens during hospital construction

An increase in the recovery of Aspergillus flavus from respiratory specimens occurred among hospitalized patients during a several-month period in 1977. Notably, 86% of the patients with positive culture results were located in an older hospital section adjacent to a building construction site that created great amounts of dust in the hospital's vicinity. Airborne contamination was suspected and results of air sampling showed A. flavus in 80% of old wing patient rooms (average, 8 A. flavus/positive room) compared with only 23% of the contiguous newer wing patient rooms (average, 1 A. flavus/positive room). Inspection of the main mechanical ventilation units in the two hospital sections disclosed numerous defects in the unit in the old wing and a properly functioning unit in the new wing. After repairing the defective unit, a significant reduction in the recovery of A. flavus from clinical and environmental specimens was noted.

Deception among smokers

Subjects in two different clinical trials who had been advised to stop smoking were asked if they had done so. Some 22% of subjects (11 out of 51) in the first trial and 40% (33/82) in the second trial who said they had stopped smoking were found to have raised carboxyhaemoglobin concentrations. Deception appears to be common in people trying to stop smoking.

The covalent coupling of proteins to periodate-oxidized sephadex: a new approach to immunoadsorbent preparation

Proteins were covalently coupled in good yield to periodate-oxidized Sephadex. The reaction was studied in detail with respect to Sephadex type, sodium m-periodate concentration, protein (albumin or immunoglobulin) concentration, time course, temperature dependence, and pH optimum. The complexes were stable and were used successfully for the immunoadsorption of sheep anti-rabbit immunoglobulin antibodies.

Two cAMP-activated protein kinases from bovine thyroid

Two cAMP-activated protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) were purified from bovine thyroid tissue by column chromatography on Sephadex G-200 and DEAE-Sephadex A-25. Maximal stimulation by cAMP of enzyme I was 1.7-fold and of enzyme II was 3.7-fold. The total (basal plus cAMP-activated) specific activities of the purified enzymes I and II were, respectively: 3190 and 6430 protein kinase units (picomoles phosphate transferred per milligram protein per 10 min).The properties of the thyroid protein kinases were found to be similar to those of protein kinases isolated from other tissues. For enzyme I, Km(cAMP) was 20 × 10−8 M, Km(cGMP) was 416 × 10−8 M, and Km(ATP) was 0.02 mM. For enzyme II, Km(cAMP) was 6 × 10−8 M, Km(cGMP) was 250 × 10−8 M, and Km(ATP) was 0.03 mM. For both enzymes, Km(histone) was 1.33 mg/ml, Km(Mg2+) was 2.6 mM, and the pH optimum lay between pH 6.0 and pH 6.5. The cAMP had no effect on the Km values of either I or II for histone, ATP, or Mg2+. The subcellular distribution study indicated that 80% of the total kinase activity was present in the 100 000 × g supernatant fraction.

Control of phosphoenolpyruvate synthesis in guinea-pig mitochondria

1. The synthesis of phosphoenolpyruvate and the O(2) consumption from the tricarboxylic acid-cycle intermediates citrate, alpha-oxoglutarate, malate and succinate by guinea-pig mitochondria were compared. Malate was the most effective of these precursors; there was no synthesis of phosphoenolpyruvate from succinate. 2. The addition of palmitate, acetoacetate and ATP enhanced the synthesis of phosphoenolpyruvate from citrate and alpha-oxoglutarate. Palmitate and ATP increased the O(2) consumption, whereas acetoacetate had no effect on this parameter. 3. Octanoate depressed the synthesis of phosphoenolpyruvate from citrate, alpha-oxoglutarate and malate and increased the O(2) consumption. Pentenoic acid had no effect on phosphoenolpyruvate synthesis from any of the substrates used, although it increased the uptake of O(2). These findings might be relevant to the control of gluconeogenesis in vivo.