Effects of phenylephrine on tissue gas tension, bleeding, infection, and lidocaine absorption

In an attempt to find a vasoconstrictor with less detrimental local and systemic effects than epinephrine, the effects of phenylephrine, a pure alpha agonist, on tissue gas tension, bleeding, infection rates, and lidocaine absorption were studied. All concentrations of phenylephrine significantly reduced tissue PO2 within 10 minutes of injection, and reduction of PO2 was dose-dependent. Phenylephrine 1:10,000 produced significant bacterial growth when simultaneously injected with 6 X 10(6) Staphylococcus aureus. Bacterial growth was insignificant with 1:20,000 phenylephrine and absent with 1:40,000 phenylephrine. Blood loss from a standard wound was significantly reduced at all concentrations of phenylephrine. Lidocaine absorption was significantly reduced with 1:20,000 and 1:40,000 phenylephrine. In a rat model, 1:40,000 phenylephrine significantly reduced blood loss and lidocaine absorption, produced minimal reduction of tissue PO2, and did not enhance bacterial invasion.     

A comprehensive review of epinephrine in the finger: to do or not to do.

The prohibition against the use of local anesthetics with epinephrine for digital blocks or infiltration is an established surgical tradition. The present article provides a comprehensive review of all reported digital necrotic and ischemic complications with epinephrine in the digits in an effort to understand whether the current prohibition is based on documented reports. A comprehensive review of articles showing the successful use of local anesthetic with epinephrine in the digits is presented.A review of Index Medicus from 1880 to 1966 and a computer review of the National Library of Medicine database from 1966 to 2000 were performed using multiple keywords. Selected major textbooks from 1900 to 2000 were also reviewed.A total of 48 cases of digital gangrene after anesthetic blocks (mostly using cocaine or procaine) have been reported in the world literature. Only 21 cases involved the use of epinephrine; 17 involved an unknown concentration based on manual dilution. Multiple other concurrent conditions (hot soaks, tight tourniquets, and infection) existed in these case reports, making it difficult to determine the exact cause of the tissue insult. There have been no case reports of digital gangrene using commercial lidocaine with epinephrine (introduced in 1948). Multiple studies involving thousands of patients support the premise that the use of lidocaine with epinephrine is safe in the digits.An extensive literature review failed to provide consistent evidence that our current preparations of local anesthesia with epinephrine cause digital necrosis, although not all complications are necessarily reported. However, as with all techniques, caution is necessary to balance the risks of this technique with the dangers of mechanical tourniquets and upper extremity block anesthesia.     

Do not use epinephrine in digital blocks: myth or truth?

The purpose of this study was to examine the role for epinephrine augmentation of digital block anesthesia by safely prolonging its duration of action and providing a temporary hemostatic effect. After obtaining approval from the review board of the authors' institution, 60 digital block procedures were performed in a prospective randomized double-blinded study. The digital blocks were performed using the dorsal approach. All anesthetics were delivered to treat either posttraumatic injuries or elective conditions. Of the 60 digital block procedures, 31 were randomized to lidocaine with epinephrine and 29 to plain lidocaine. Of the procedures performed using lidocaine with epinephrine, one patient required an additional injection versus five of the patients who were given plain lidocaine (p = 0.098). The need for control of bleeding required digital tourniquet use in 20 of 29 block procedures with plain lidocaine and in 9 of 31 procedures using lidocaine with epinephrine (p < 0.002). Two patients experienced complications after plain lidocaine blocks, while no complications occurred after lidocaine with epinephrine blocks (p = 0.23). By prolonging lidocaine's duration of action, epinephrine may prevent the need for an additional injection and prolong post-procedure pain relief. This study demonstrated that the temporary hemostatic effect of epinephrine decreased the need for, and thus the potential risk of, using a digital tourniquet (p < 0.002). As the temporary vasoconstrictor effect is reversible, the threat of complication from vasoconstrictor-induced ischemia is theoretical.     

Properties of a local anesthetic receptor in rat brain

Saturable binding of local anesthetics in rat brain homogenates was demonstrated using (14C)-lidocaine and (3H)-bupivacaine. Saturation analyses revealed a single class of binding sites for lidocaine and bupivacaine. A series of drugs with local anesthetic properties inhibited this binding, while drugs without local anesthetic activity did not affect the specific binding. Specific binding of lidocaine and bupivacaine was maximal from pH 8 to 10; the pH versus binding profile was similar to that reported for local anesthetic blocking of peripheral nerve conduction. These characteristics suggest that binding of local anesthetics to this or similar sites mediates their pharmacological activity.     

Simultaneous determination of local anesthetics including ester-type anesthetics in human plasma and urine by gas chromatography–mass spectrometry with solid-phase extraction

The present study describes the simultaneous determination of seven different kinds of local anesthetics and one metabolite by GC–MS with solid-state extraction: Mepivacaine, propitocaine, lidocaine, procaine (an ester-type local anesthetics), cocaine, tetracaine (an ester-type local anesthetics), dibucaine (Dib) and monoethylglycinexylidide (a metabolite of lidocaine) were clearly separated from each other and simultaneously determined by GC–MS using a DB-1 open tubular column. Their recoveries ranged from 73–95% at the target concentrations of 1.00, 10.0 and 100 μg/ml in plasma, urine and water. Coefficients of variation of the recoveries ranged from 2.3–13.1% at these concentrations. The quantitation limits of the method were approximately 100 ng/ml for monoethylglycinexylidide, propitocaine, procaine, cocaine, tetracaine and dibucaine, and 50 ng/ml for lidocaine and mepivacaine. This method was applied to specimens of patients who had been treated with drip infusion of lidocaine, and revealed that simultaneous determination of lidocaine and monoethylglycinexylidide in the blood and urine was possible.     

Cocaine and its derivatives blunt neutrophil functions without influencing phosphorylation of a 47-kilodalton component of the reduced nicotinamide-adenine dinucleotide phosphate oxidase

Cocaine and its derivatives blunted responses of neutrophils (cell/cell aggregation, up-regulation of the receptor for C3bi (CR3, CD11b/CD18), generation of superoxide anion (O2-) and degranulation to various stimuli. The order of potency of these agents was the same as that for local anesthesia: tetracaine greater than bupivacaine greater than cocaine greater than lidocaine. Neutrophil aggregation elicited by the chemoattractant FMLP (10(-7) M) was inhibited by cocaine (10 mM) to 13.6 +/- 6% of control (p less than 0.002); the IC50 was approximately 4 mM. Cocaine and the other local anesthetics not only inhibited the upregulation of CR3 and O2- generation, but also blocked degranulation of cytochalasin B-treated cells. Cocaine (10 mM) reduced beta-glucuronidase and lysozyme secretion to 4.3 +/- 0.7 and 13 +/- 2.2% controls, respectively; its IC50 was 4 mM. Local anesthetics added after ligand/receptor engagement (FMLP) interrupted aggregation and halted generation of O2-. Moreover, local anesthetics rapidly inhibited aggregation, O2- generation, and degranulation elicited by PMA (1 microgram/ml) or the Ca ionophore A23187 (10 microM): the effects of cocaine could therefore not be attributed to unique actions at the FMLP receptor. Peak levels of intracellular Ca2+ ([Ca]i) at 5 to 10 s, and levels of [Ca]i 120 s after FMLP in Fura 2-loaded cells were significantly lower in cells treated with lidocaine, findings that could be explained by enhanced 45Ca2+ efflux from neutrophils. In cells loaded with bis(carboxyethyl)carboxyfluorescine (pH indicator) local anesthetics failed to affect the initial FMLP-induced (0 to 15 s) drop of pHi but inhibited the later (120 s) realkalinization of the cytosol (lidocaine, bupivacaine). Most remarkably, autoradiographs of SDS gels prepared from stimulated, 32P-labeled neutrophils treated with local anesthetics showed no difference from resting cells, either with respect to patterns of phosphorylation and dephosphorylation or their kinetics. Labeling of a 47-kDa protein, a component of the reduced nicotinamide-adenine dinucleotide phosphate-oxidase system, was unchanged. The effects of local anesthetics, which blunt neutrophil responses without affecting protein phosphorylation, suggest that protein phosphorylation is an insufficient signal for neutrophil activation. Inasmuch as cocaine and its derivatives affect cell functions at sites distal to activation of protein kinase C, these agents should prove useful in uncoupling protein phosphorylation from functional responses.     

Comparison of the intracellular bacterial killing activity of leukocytes in musculocutaneous and random-pattern flaps

The in vivo physiologic response to gram-negative bacterial inoculation within wound cylinder spaces enclosed by the deep surface of paired musculocutaneous and random-pattern flaps was studied in the canine model. Leukocyte function was assessed by calculating the following values: leukocyte counts, bacterial counts, phagocytic indices, and intracellular bacterial killing ratios. The following results were observed in the wound cylinder spaces after bacterial inoculation with 5 X 10(7) of Pseudomonas aeruginosa bacteria: (1) the numbers of mobilized leukocytes within each wound cylinder space flap were not statistically different, (2) the bacterial counts were significantly lower in the musculocutaneous flap wound cylinder space at both 24 and 48 hours, (3) the phagocytic activity of the leukocytes within musculocutaneous flap wound cylinder space was 1.5 times greater than the leukocytes in the random-pattern flap wound cylinder space, and (4) the intracellular bacterial killing ratio of the musculocutaneous flap leukocyte was 83 percent versus 26 percent in the random-pattern flap leukocyte, a significant difference.     

Determinants of poor outcome after laceration and surgical incision repair

The most important outcomes after repair of traumatic lacerations and surgical incisions are their long-term cosmetic appearance and development of infection. However, few studies have attempted to identify patient and wound characteristics associated with increased infection rates and suboptimal scar appearance. The authors determined patient and wound characteristics associated with wound infection or suboptimal appearance after laceration or incision repair. A secondary analysis of data collected from a multicenter randomized clinical trial comparing the outcome of lacerations and incisions closed with tissue adhesive or standard closure methods conducted at 10 clinical inpatient and outpatient sites was performed. The presence of infection and scar appearance were prospectively determined using validated outcomes. Univariate and multivariate analyses were performed to identify patient and wound characteristics associated with poor wound outcome (wound infection at 5 to 10 days or suboptimal appearance at 3 months). Eight hundred fourteen patients with 924 wounds (383 lacerations, 541 incisions) were enrolled. Mean age was 32 years and 47 percent were female. Characteristics associated with suboptimal cosmetic appearance on multivariate analysis were presence of associated tissue trauma [odds ratio (OR), 3.9; 95 percent confidence interval (CI), 1.4 to 10.7], use of electrocautery (OR, 3.4; 95 percent CI, 1.8 to 6.5), incomplete wound edge apposition (OR, 2.9; 95 percent CI, 1.7 to 5.0); extremity location (OR, 2.1; 95 percent CI, 1.2 to 3.7), and wound width (OR, 1.08; 95 percent CI, 1.01 to 1.14). Characteristics associated with wound infection on univariate analysis included associated tissue trauma (8.7 percent versus 1.2 percent, p = 0.04) and incomplete wound apposition (6.6 percent versus 0.5 percent). Suboptimal appearance was more common in infected wounds (relative risk, 3.2; 95 percent CI, 1.8 to 5.6). Suboptimal wound appearance is increased with extremity wounds, wide wounds, incompletely apposed wounds, associated tissue trauma, use of electrocautery, and infection. Type of closure device and use of deep sutures had no effect on infection rates or cosmetic appearance.     

A comparison of absorbable and nonabsorbable suture materials for skin repair.

This prospective clinical study was conducted to compare the outcome of elective surgical wound repair in the occipital region during rhytidectomy using absorbable and nonabsorbable suture materials. On an alternative basis, 6-0 polypropylene and 6-0 plain catgut were used to repair the incisions on the upper and lower half of the surgical wounds in 80 sites. These sites were then compared for stitch marks, erythema, hypertrophic scars, infection, and wound necrosis. This study revealed slightly visible stitch marks in 4 of 40 (10 percent) sites repaired with catgut and in 10 of 40 (25 percent) sites repaired with polypropylene material (p less than 0.10); however, this was not statistically significant. There were five incidences of suture-site erythema (12.5 percent) noted in the group of catgut repairs in comparison with three incidences (7.5 percent) in the group repaired using polypropylene. Furthermore, there was no statistically significant difference in hypertrophic scarring or infection rate between these groups. The incidence of erythema following repair with catgut was higher, but this was also not statistically significant. Considering these findings, coupled with the avoidance of patient discomfort, suture removal, and time spared for the surgeon and staff when absorbable suture material is used, the superiority of plain catgut over nonabsorbable material becomes evident.     

Plasma lidocaine levels during augmentation mammaplasty and suction-assisted lipectomy

Many plastic surgical procedures are dependent on or aided by the use of local anesthetics. Drug toxicity, although uncommon, is the most feared complication of this technique. There are multiple factors that lead to varying drug levels. These include drug concentration, speed of injection, rate of degradation, total dosage, site of injection or application, rate of administration, and the adjunctive use of vasoconstrictors. This study evaluates the use of subcutaneously injected lidocaine in patients undergoing suction-assisted lipectomy and augmentation mammaplasty. Lidocaine in the concentration of 0.5% containing either 1:100,000 or 1:200,000 epinephrine was used in doses up to 500 mg. Serial lidocaine levels were then obtained up to 1 1/2 hours after injection utilizing two different assay techniques. Our findings demonstrate consistently nondectable serum lidocaine levels despite the use of doses in excess of recommended "safe" amounts. This suggests that under specific circumstances and with certain operative procedures, lidocaine dosing can be liberalized.     

Plasma concentrations of monoethylglycinexylidide during and after breast augmentation

MEGX (monoethylglycinexylidide) is the main metabolite of lidocaine and is 83 percent as potent as an antiarrhythmic drug and with the same toxicity as lidocaine. In this study, plasma levels of MEGX were measured in 10 other wise healthy women during and after breast augmentation. A total dose of 825 to 1,280 mg of lidocaine of 0.2% and 0.5% lidocaine with epinephrine corresponding to 16.3 to 21.8 mg/kg (mean, 18.2 mg/kg) was injected in the spatium between the pectoralis muscle and the mammary gland. The peak plasma concentrations of MEGX varied between 0.40 and 0.99 microg/ml (mean, 0.49 microg/ml) and occurred between 8 and 12 hours (mean, 9.1 hours), postoperatively. In three patients, the concentration of MEGX was still increasing after 12 hours. In comparison, the peak plasma concentrations of lidocaine varied between 0.96 and 3.12 microg/ml (mean, 1.49 microg/ml) and occurred between 4 and 12 hours (mean, 7.3 hours) after the end of the injection. The peak lidocaine + MEGX concentrations varied between 1.45 and 3.58 microg/ml (mean, 2.02 microg/ml) and occurred between 5 and 12 hours (mean, 8.5 hours), postoperatively. These data suggest that MEGX might contribute to lidocaine toxicity when high doses of lidocaine are injected. The substantial interindividual variation strongly indicates that recommendations about maximum safe doses of lidocaine should be made with caution.     

Balance of tumor necrosis factor alpha and interleukin-10 in a buccal infection in a streptozotocin-induced diabetic rat model

This study evaluates the local levels of proinflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), and anti-inflammatory cytokine, interleukin-10 (IL-10), in an experimental buccal abscess of a diabetic rat model. We prepared a buccal cavity induced by injection of carrageenin in a diabetic rat (blood glucose, 460.6 +/- 54.7 mg/dl, mean +/- SE) induced by streptozotocin (STZ). The buccal abscess was formed by the direct inoculation of Streptococcus pyogenes S-8 (2 x 10(7) cfu) into the buccal cavity at day 5 after carrageenin injection. Cytokine levels in the exudate of the buccal abscess were measured by enzyme-linked immunosorbent assay for 48 h after infection. Bacterial counts, weighing of exudate, and histological analysis were also performed. The mean TNF-alpha levels in the buccal abscess exudate of the diabetic group, which were generally higher than those of the control group, tended to increase over time until 48 h after infection, while the TNF-alpha levels in the control group peaked at 24 h after infection and then decreased. The IL-10 levels in the diabetic group remained almost unchanged until 48 h after infection, while the IL-10 levels in the control group were significantly higher than in the diabetic group at 12-24 h after infection. The mean ratio of TNF-alpha to IL-10 levels was 1.17-1.67 in the diabetic group, which was higher than the 0.26-0.69 of the control group. The bacterial counts in the buccal abscess and the weight of exudate were significantly higher in the diabetic group compared to the control group at 36-48 h. Histological findings showed that inflammatory cell infiltration was remarkable in the diabetic group compared to that of the control group. These results suggest that the elevated proinflammatory TNF-alpha levels and decreased anti-inflammatory IL-10 levels, which are produced at local infection sites, may at least in part be related to the severity of inflammation in this rat model with diabetes induced by STZ.     

Local anesthetic inhibition of pancreatic phospholipase A2 action on lecithin monolayers.

Using quantitative data previously reported for the penetration of local anesthetics into lecithin monolayers, the effects of surface and subphase concentrations of anesthetics on the inhibition of pancreatic phospholipase A2 action on didecanoyl phosphatidylcholine monolayers was investigated. Inhibition as a function of subphase concentration of anesthetic was in the order: dibucaine greater than tetracaine greater than butacaine greater than lidocaine = procaine. Inhibition as a function of surface concentration showed no obvious correlation; procaine inhibited at a very low surface concentration, followed by lidocaine at a somewhat higher concentration, and tetracaine, butacaine and dibucaine only at rather high concentrations. Ultraviolet difference spectroscopy indicated an interaction between lidocaine and enzyme in the subphase. Fluorescence studies showed that lidocaine is a competitive inhibitor of enzyme-lipid interface interaction. It is proposed that the more surface-active anesthetics inhibit by surface effects while the less surface-active anesthetics (lidocaine and procaine) inhibit by interaction with the enzyme in the subphase, which prevents enzyme penetration at the monolayer interface.     

The effect of muscle flap transposition to the fracture site on TNFalpha levels during fracture healing

The trauma and sepsis that follow open fractures and wounds may lead to the production of various cytokines. Understanding wound healing requires a direct knowledge of the specific cytokines and the respective wound fluid levels that are present at the wound site. An animal model was designed that mimics the open fracture and the clinical repair of the human, high-energy open fracture. Canine right tibiae were fractured with a penetrating, captive-bolt device, then repaired in a standard clinical fashion using an interlocking intramedullary nail. Before primary wound closure, microdialysis probes were placed at the fracture site and in a muscle located at a contralateral site. Canines received one of the following experimental protocols: (1) tibial fracture (n = 5); (2) tibial fracture plus Staphylococcus aureus inoculation at the fracture site (n = 5); and (3) tibial fracture, S. aureus inoculation, and a rotational gastrocnemius muscle flap (n = 5). Microdialysis fluid samples were collected intermittently for 7 days. Tumor necrosis factor alpha (TNFalpha) levels at the fracture site were significantly elevated 3 to 34-fold (p<0.02), as compared with respective serum levels at all time points for all treatment groups. Fracture site TNFalpha levels were elevated (p<0.02) in days 1 through 6, as compared with the baseline and contralateral in all treatment groups. At days 1 through 6, the TNFalpha levels of the muscle flap group fracture site were significantly decreased by approximately 50 percent (p<0.05), as compared with the fractures without muscle flaps and regardless of additional S. aureus inoculation. On day 7, fracture site TNFalpha levels in all animal groups were similar, yet remained well above those of baseline TNFalpha. These results demonstrate that S. aureus does not further elevate TNFalpha levels in the presence of an open fracture and that a muscle flap reduces pro-inflammatory TNFalpha levels during early wound healing. This experimental model allows for the characterization of specific biological signals and cellular pathways that are influenced by bacterial infection and surgical closure. These data provide a scientific framework on which to judge or validate therapeutic regimens for open-fracture wound healing.     

烧烫伤创面感染的小鼠模型构建

目的探讨一种简单、稳定的烧烫伤创面感染的小鼠模型构建方法,以便进行相关烧烫伤创面修复研究。方法取30只BALB/c小鼠,采用自制木质烫伤板,沸水浴法烫取直径8 mm的圆形创面,烫伤时间分别为5 s、10 s、15 s。伤后48 h,取创面组织进行HE染色观察,筛选最佳创面烫伤时间。另取72只小鼠制成深Ⅱ度烫伤创面,采用擦刮法分别接种20μL菌浓度为1×106、l×107、1×108CFU/mL金黄色葡萄球菌标准菌株ATCC 25923的菌液。接种细菌后72 h,取创面组织HE染色观察创面炎症反应情况,并测定3、7、14 d的皮肤菌负荷,筛选最佳的细菌接种浓度。最后,按最佳条件建模后,观察创面的完全愈合时间以及创面愈中、愈后的组织学变化,以确定此创面感染模型是否建立成功。结果组织学结果表明,10 s为深Ⅱ度创面的理想致伤时间,最佳接种菌浓度为l×108CFU/mL,此时期,14 d内菌负荷均高于l×105CFU/g。该模型的创面愈合时间(21±0.95 d)较正常创面愈合时间(15.92±0.34 d)明显延长(P<0.01),炎性反应明显,愈后不佳。结论烧烫伤创面感染的小鼠模型构建成功,可作为感染创面防治研究的实验动物模型。     

Experimental and clinical study of immunomodulators Immunomax and Gepon in complex treatment of acute purulent surgical infection]

The efficacy of the immunomodulators immunomax and gepon in the treatment of acute purulent surgical infection of soft tissues was studied under experimental and clinical conditions. Gepon was used in the form of 0.04% ointment in the phase of the wound infection regeneration vs. the routine use of 10% methyluracil ointment. Immunomax was administered in a dose of 40 units under the experimental conditions and 200 units in the clinical trial 3 times every 2nd day intramuscularly. The experimental investigation was performed on 20 male guinea pigs in a model of a suppurating wound. The animals were divided into 2 groups (main and control) of 10 animals each. Flat wounds were prepared according to the A. V. Nikolaev's method. The clinical trial enrolled 126 patients with acute surgical infection of the soft tissues. The patients were treated in the Hospital of General Surgery of the Faculty of Pediatrics of the Russian State Medical University during the period from 2003 to 2004. The patients were divided into 2 groups (main and control). The structure of the main and control groups was comparable by the sex and age of the patients, nosological forms and severity of the disease. The patients of the main group (65 subjects) were given the immunomodulators in complex with the routine surgical treatment and drug therapy. The patients of the control group (61 subjects) were given the same surgical treatment and drug therapy but without the use of the immunomodulators. General and local manifestations of the purulent infection were considered as the criteria of the treatment efficacy. The qualitative and quantitative composition of the wound bacterial infection was determined and histological examination of the wound bioptates was performed. Planimetry of the wound surface was carried out and the acceleration index of the wound clearing and healing was evaluated. In the total, high therapeutic efficacy of immunomax and gepon, practically no contraindications and adverse reactions to their use, the ease and simplicity of their handling can be stated.     

Transformation of sweet orange [Citrus sinensis (L.) Osbeck] with pthA-nls for acquiring resistance to citrus canker disease

The COOH terminal of pthA encoding three nuclear localizing signals (NLS) was amplified by polymerase chain reaction (PCR) from the plasmid of Xanthomonas axonopodis pv. citri, the pathogen of citrus canker disease. Then the sense and antisense strands of the nls were cloned into pBI121 vector. pthA-nls driven by the CaMV35 s promoter was transferred into sweet orange via Agrobacterium -mediated transformation. Successful integration was confirmed by PCR and Southern blotting, and 12 sense-nls (nls (+)) and 9 antisense-nls (nls (-)) transgenic clones were obtained. The expression of nls fragment was analyzed by RT-PCR, Real time q-PCR and Western blotting, in which the specific NLS protein was detected only in nls (+) transgenic clones. In an in vitro assay, when pin-puncture inoculation was performed with 2.5 × 10(7) cfu/ml of bacterial solution, the nls (+) transgenic clones showed no typical lesion development, while typical symptoms were observed in the wild types and the nls (-) transgenic clones. In vivo assay results indicated that the nls (+) transgenic clones showed less disease incidence, in comparison with the wild types and the nls (-) transgenic clones, when pin-puncture inoculation was performed with 10(4)-10(5) cfu/ml. The minimum disease incidence was 23.3% for 'Sucarri' sweet orange and 33.3% for 'Bingtang' sweet orange. When 10(4)-10(7) cfu/ml of pathogen was spray inoculated, the nls (+) transgenic clones did not show any symptom, and even the concentration raised to 10(9) cfu/ml, the disease incidence was 20-80%, while the wild types and the nls (-) transgenic clones had 100% disease development with whatever concentration of inoculum. Two transgenic clones were confirmed to be resistant to citrus canker disease in the repeated inoculation. The results suggested that the transformation of nls sense strands may offer an effective way to acquire resistance to citrus canker disease.     

Effect of local anesthetics and phorbol ester on intracellular pH and rate of development of sea urchin embryos

The unfertilized eggs of sand-dollars (Scaphechinus mirabilis) were treated with local anesthetics (novocaine, lidocaine, trimecaine) or phorbol ester for 10 min. The treatment with the local anesthetics increased pH of the cytoplasm in the unfertilized eggs (pHc) and changed the value of the pHc increment in response to fertilization, as compared with the control eggs. In the treated embryos, the onset of immigration of the primary mesenchyme cells was delayed but the hatching was accelerated. The phorbol ester treatment rapidly accelerated development from gastrulation on and practically did not affect the preceding stages.     

Extrauterine Listeriosis in the Gravid Mouse Influences Embryonic Growth and Development

Gravid mice and other rodents inoculated with Listeria monocytogenes typically fail to clear an intrauterine infection and either succumb or expel their intrauterine contents. We took advantage of this property to investigate the effects of an extrauterine infection on parameters of pregnancy success. Pregnant mice were selected for our study if they showed no clinical signs of listeriosis following oral inoculation at 7.5 gestational days (gd), and had no detectable intrauterine colony forming units (cfu) at near term (18.5 gd). The range of oral doses employed was 10⁶-10⁸ cfu per mouse for two listerial serotype strains (4nonb and 1/2a). At all doses, inoculation resulted in a decrease in average near-term (18.5 gd) fetal weight per litter compared to sham inoculated controls. Additionally, embryonic death (indicated by intrauterine resorptions) was exhibited by some inoculated mice but was absent in all sham inoculated animals. In parallel experiments designed to detect possible loss of placental function, gravid uteruses were examined histopathologically and microbiologically 96 h after oral inoculation. Placental lesions were associated with high (> 10⁶), but not low (< 10²) or absent intrauterine cfu. In vitro, mouse embryonic trophoblasts were indistinguishable from mouse enterocytes in terms of their sensitivity to listerial exposure. A model consistent with our observations is one in which products (host or bacterial) generated during an acute infection enter embryos transplacentally and influences embryonic survival and slows normal growth in utero.