The Stickland Reaction Precursor trans-4-Hydroxy-l-Proline Differentially Impacts the Metabolism of Clostridioides difficile and Commensal Clostridia.

An intact gut microbiota confers colonization resistance against Clostridioides difficile through a variety of mechanisms, likely including competition for nutrients. Recently, proline was identified as an important environmental amino acid that C. difficile uses to support growth and cause significant disease. A posttranslationally modified form, trans-4-hydroxyproline, is highly abundant in collagen, which is degraded by host proteases in response to C. difficile toxin activity. The ability to dehydrate trans-4-hydroxyproline via the HypD glycyl radical enzyme is widespread among gut microbiota, including C. difficile and members of the commensal Clostridia, suggesting that this amino acid is an important nutrient in the host environment. Therefore, we constructed a C. difficile ΔhypD mutant and found that it was modestly impaired in fitness in a mouse model of infection, and was associated with an altered microbiota when compared to mice challenged with the wild-type strain. Changes in the microbiota between the two groups were largely driven by members of the Lachnospiraceae family and the Clostridium genus. We found that C. difficile and type strains of three commensal Clostridia had significant alterations to their metabolic gene expression in the presence of trans-4-hydroxyproline in vitro. The proline reductase (prd) genes were elevated in C. difficile, consistent with the hypothesis that trans-4-hydroxyproline is used by C. difficile to supply proline for energy metabolism. Similar transcripts were also elevated in some commensal Clostridia tested, although each strain responded differently. This suggests that the uptake and utilization of other nutrients by the commensal Clostridia may be affected by trans-4-hydroxyproline metabolism, highlighting how a common nutrient may be a signal to each organism to adapt to a unique niche. Further elucidation of the differences between them in the presence of hydroxyproline and other key nutrients will be important in determining their role in nutrient competition against C. difficile. IMPORTANCE Proline is an essential environmental amino acid that C. difficile uses to support growth and cause significant disease. A posttranslationally modified form, hydroxyproline, is highly abundant in collagen, which is degraded by host proteases in response to C. difficile toxin activity. The ability to dehydrate hydroxyproline via the HypD glycyl radical enzyme is widespread among gut microbiota, including C. difficile and members of the commensal Clostridia, suggesting that this amino acid is an important nutrient in the host environment. We found that C. difficile and three commensal Clostridia strains had significant, but different, alterations to their metabolic gene expression in the presence of hydroxyproline in vitro. This suggests that the uptake and utilization of other nutrients by the commensal Clostridia may be affected by hydroxyproline metabolism, highlighting how a common nutrient may be a signal to each organism to adapt to a unique niche. Further elucidation of the differences between them in the presence of hydroxyproline and other key nutrients will be important to determining their role in nutrient competition against C. difficile.

Successful treatment of a chronic oroantral fistula infected with extensively drug resistant bacteria using long-term oesophageal tube feeding and several non-conventional treatments in a horse.

BACKGROUND: Chronic oroantral fistulae (OAF) with secondary sinusitis can occur following repulsion of cheek teeth in horses. CASE REPORT: An 8-year-old Andalusian cross gelding presented with an iatrogenic clinical crown fracture of tooth 209, which underwent repulsion of its apical portion (day 0). The horse was treated with intramuscular penicillin and intravenous gentamicin (5 days), followed by oral trimethoprim-sulphonamide (10 days) and then oral doxycycline (14 days). The acute iatrogenic OAF created during the initial repulsion persisted; a chronic OAF was identified on day 24. On day 48, septic sinusitis with multidrug-resistant (MDR) Escherichia coli was confirmed. Although susceptible to enrofloxacin in vitro, 30 days of therapy was unsuccessful. Subsequent serial cultures grew multiple MDR and extensively drug-resistant (XDR) gram-negative microorganisms. Whole-genome sequencing (WGS) revealed multiple sequence types of E. coli, with a range of resistance and virulence genes. The orientation of the OAF, regional osteomyelitis and septic sinusitis were confirmed with computed tomography on day 70. On day 74, enteral nutrition was provided through a cervical oesophagostomy tube for 3 months for prevention of oral feed contamination. The OAF was treated with various alternative therapeutics, including apple cider vinegar, propolis and amikacin impregnated products, until resolution on day 116. CONCLUSION: These non-conventional therapeutics, antimicrobials and long-term oesophagostomy contributed to the successful treatment of a complicated OAF. In the future, WGS may be useful to inform antimicrobial selection when MDR or XDR organisms are identified.

Synergistic effects of cyclic AMP and nerve growth factor on neurite outgrowth and microtubule stability of PC12 cells.

The outgrowth of neurites from rat PC12 cells stimulated by combined treatment of nerve growth factor (NGF) with cAMP is significantly more rapid and extensive than the outgrowth induced by either factor alone. We have compared the responses of PC12 cells under three different growth conditions, NGF alone, cAMP alone, and combined treatment, with respect to surface morphology, rapidity of neurite outgrowth, and stability of neurite microtubules, to understand the synergistic action of NGF and cAMP on PC12. Surface events at early times in these growth conditions varied, suggesting divergent pathways of action of NGF and cAMP. This suggestion is strongly supported by the finding that cells exposed to saturating levels of dibutyryl cAMP without substantial neurite outgrowth initiated neurites within 5 min of NGF. This response has been adopted as a convenient assay for NGF. Neurites that regenerated in the three growth conditions showed marked differences in stability to treatments that depolymerize microtubules. The results indicate that microtubules in cells treated with both NGF and cAMP are significantly more stable than in either growth factor alone. We suggest that a shift of the assembly equilibrium favoring tubulin assembly is a necessary prerequisite for the initiation of neurites by PC12.

Local dental anesthesia with epinephrine. Minimal effects on the sympathetic nervous system or on hemodynamic variables.

To define the hemodynamic effects of local dental anesthesia, we measured the mean arterial pressure (MAP), heart rate, and plasma catecholamine responses for 60 minutes following an inferior alveolar nerve block with epinephrine-and nonepinephrine-containing lidocaine hydrochloride anesthesia in 14 men using a randomized double-blind crossover trial. Lidocaine alone caused no significant change in MAP or heart rate and only slight, transient changes in plasma catecholamine concentrations when compared with baseline values. Lidocaine with epinephrine caused significant, sustained (60 minutes) increases in plasma epinephrine concentrations (mean +/- SEM, 27 +/- 4 to 94 +/- 13 pg/mL) and a slight, but transient (two-minute) increase in heart rate from 68 +/- 3 to 70 +/- 3 beats per minute. Lidocaine with epinephrine caused no significant change in MAP. There is no significant hemodynamic response to lidocaine dental anesthesia (with or without epinephrine) in healthy young men.

Hormonal responses to graded surgical stress.

We tested the hypothesis that selected hormonal responses to surgery reflect the degree of surgical stress. Plasma norepinephrine, epinephrine, thromboxane B2, cortisol, serum angiotensin converting enzyme, thyroxine, triiodothyronine, free thyroxine, and free triiodothyronine levels were measured preoperatively, and then one hour, 24 hours, and five days postoperatively in three groups of patients. The groups were as follows: group 1, "minimal" stress, eg, inguinal hernia repair (n = 10); group 2, "moderate" stress, eg, cholecystectomy (n = 12); and group 3, "severe" stress, eg, subtotal colectomy (n = 9). Patients in group 1 showed no significant surgery-induced changes in hormonal values. The stress-induced changes in patients in groups 2 and 3 were seen at one and occasionally 24 hours; however, by five days postoperatively, circulating hormone values had returned to preoperative levels. Increases in plasma cortisol, norepinephrine, and epinephrine, and decreases in serum angiotensin converting enzyme levels characterized the surgery-induced hormonal changes. Conclusions are as follows: hormonal responses do reflect the degree of surgical stress; the hormonal changes are transient, lasting no longer than 24 hours in patients after uncomplicated surgery; hormonal responses to minimal surgical stress are negligible.

Relationship between Russian roulette deaths and risk-taking behavior: a controlled study.

A review of medical examiner records yielded data on 19 men and one woman who died playing Russian roulette. The men differed significantly from 95 male suicide victims who died of gunshot wounds to the head on several variables including age, race, ethnicity, religion, citizenship, marital status, living situation, health, and the likelihood of the death being witnessed. The Russian roulette victims were significantly less likely to die in the bedroom, die in the morning, leave a suicide note, and be depressed but were significantly more likely to have alcohol or drugs in their body fluids and to have a previous history of drug and alcohol abuse.

Improved survival in the suckling rat model of group B streptococcal sepsis after treatment with nonsteroidal anti-inflammatory drugs.

The nonsteroidal anti-inflammatory drugs, indomethacin and ibuprofen, have been shown to increase survival in various animal models of Gram-negative or endotoxin shock. To evaluate the use of these drugs in group B streptococcal sepsis, a clinically similar disease state, a newborn suckling rat model (4 to 5 days old) designed to simulate early-onset group B streptococcal sepsis was used. Sepsis was induced by a subcutaneous injection of group B streptococcal organisms (type III). A mortality ranging from 30% to 90% was used for the study. Indomethacin (3 mg/kg) or ibuprofen (4 mg/kg) treatment was administered by an intraperitoneal injection either at the time of the bacterial injection or after bacteremia (four hours) had occurred. Indomethacin clearly improved survival rates, even when given after bacteremia. Ibuprofen also clearly increased survival when given at the same time as the bacterial injection. Ibuprofen was more effective than indomethacin in the high mortality model (lethal dose for 90% survival of group). These drugs alter mechanisms that may be important in the irreversibility of sepsis and they may become useful adjuvants to our present treatment of early onset group B streptococcal sepsis.

E. coli endotoxin shock in the dog; treatment with lidocaine or indomethacin.

1 Dogs treated with lidocaine (1 mg kg-1 h-1) or indomethacin (1.5 mg/kg) before and after an LD60 dose (1 mg/kg) of E. coli endotoxin survived for at least 72 h. 2 Although all dogs in both treated groups survived, only those treated with indomethacin were significantly protected against the fall in the arterial blood pressure 1 to 2 min following endotoxin administration. 3 Endotoxin increased the plasma prostaglandin F2alpha (PGF2alpha) concentration in the control and lidocaine-treated groups, however, no increase was observed with indomethacin treatment. 4 Neither lidocaine nor indomethacin alone had any significant effect on the parameters measured in this model. 5 Following the administration of endotoxin, lidocaine-treated animals had significantly decreased plasma fibrinogen concentrations when compared to the other groups. 6 This study suggests that lidocaine, a local anaesthetic and a drug widely used for cardiac arrhythmias, might offer protection in endotoxin shock.

Modification, by aspirin and indomethacin, of the haemodynamic and prostaglandin releasing effects of E. coli endotoxin in the dog.

1 Dogs treated with aspirin (10 mg/kg) or indomethacin (1.5 mg/kg) 45 min before, and 3 h after, an LD50 dose (1 mg/kg) of E. coli endotoxin were alive 72 h later. 2 Although all dogs in both treated groups survived, only those treated with indomethacin were protected against the fall in blood pressure 1-2 min following endotoxin. 3 Endotoxin increased the level of prostaglandin F2alpha in both the mixed venous and arterial blood. No increase was observed in the aspirin and indomethacin-treated groups. 4 Aspirin and indomethacin treatment did not modify thrombocytopaenia or blood coagulation parameters following endotoxin.

Nadolol to treat aggression and psychiatric symptomatology in chronic psychiatric inpatients: a double-blind, placebo-controlled study.

BACKGROUND: Considerable evidence indicates that the lipophilic beta-blocker propranolol is useful in treating organically based aggression. This study looked at the efficacy of a more hydrophilic beta-blocker, nadolol, to treat aggression in chronic psychiatric inpatients. METHOD: Forty-one chronic psychiatric inpatients with an average of one aggressive outburst per week (defined by the Overt Aggression Scale [OAS]) were entered into a double-blind, placebo-controlled study lasting 17 weeks. The OAS was used to track aggression on a per-incident basis, while the Brief Psychiatric Rating Scale (BPRS) and the Clinical Global Impressions scale (CGI) were used to track clinical status. RESULTS: Nadolol subjects showed a significant decline in frequency of aggression compared with controls (p = .026) and a significant decline in the BPRS total score (p = .007) and in the subfactors "hostility and suspicion," "negative symptoms," and "signs of hyperarousal/tension." There was no significant change in CGI "severity of illness" ratings between groups, although the nadolol group was significantly improved from baseline at every subsequent time period while the placebo group was unchanged throughout the study. CONCLUSION: Nadolol is of significant benefit in the treatment of aggression in chronic psychiatric inpatients. This drug does penetrate the brain over time, but the success of a drug whose primary locus of action is peripheral may implicate a bimodal mechanism of action, i.e., a role for the CNS and the soma in the maintenance of aggression.

Twenty-four hour membrane oxygenation in dogs without anticoagulation.

Is systemic heparinization or heparin-bonded circuitry better than no anticoagulation during 24 hours of cardiopulmonary bypass? We compared blood pressure, coagulation state, oxygenator function, and scanning electron microscopic appearance of the circuits. There were three groups of five dogs each: Group I had no anticoagulants; Group II received systemic heparization; Group III perfusions utilized heparin-bonded circuits. Group I animals all survived, whereas 80 percent (four fifths) in Group II and 20 percent (one fifth) in Group III survived. Arterial pressures were better maintained in Group I as compared to Groups II and III. The coagulation parameters were similar in all groups. Oxygenator function was maintained at normal in all groups. No thrombi were present in any of the circuits following perfusion. The surfaces in Group I had less debris on them compared to Groups II and III. Animals that died had fibrin thrombi present in tissues examined histologically. Systemic heparinization had no advantage over no heparin in this study. The striking similarity of the coagulation state between Groups I and II and better preservation of the surfaces in Group I were unexpected. Heparin-bonded circuits were unsatisfactory when compared to no anticoagulation and systemic heparinization. Additional experiments with various species with and without anticoagulation must be done to determine the best guidlines for human cardiopulmonary bypass.

Eicosanoids. Critical agents in the physiological process and cellular injury.

Eicosanoids were discovered as "prostaglandins" in the mid-1930s. The discovery that eicosanoids were ubiquitous in mammalian cells and that nonsteroidal anti-inflammatory drugs worked by inhibiting enzymes that synthesized these chemicals heralded their extensive investigation in all fields of biology. Precursor fatty acids (arachidonic acids) are stored in cell phospholipids, acted on by two enzymes (cyclooxygenase and lipooxygenase) that yield prostaglandins, thromboxane, prostacyclin, and leukotrienes. Knowledge of their biochemical processes continue to unfold, but it is now believed that eicosanoids are part of a larger group of agents termed phospholipid mediators. Eicosanoids are intimately involved with cardiovascular function as well as central and peripheral vascular disease processes and ischemia. In the gastrointestinal tract, these potent lipids not only participate in many normal functions (eg, acid secretion and motility) but also in disease states (eg, inflammatory bowel disease and peptic ulcer disease). In shocklike states of sepsis and/or endotoxemia, eicosanoids have assumed a major role in many events that occur. Recently, discoveries have demonstrated that platelet-activating and tumor necrosis factors exert their effects in part through eicosanoids. The future will demonstrate these compounds to be critical not only in intracellular (molecular) events but also in the effects they produce that are far from the source of origin.

Antimicrobial prophylaxis for surgical wounds. Guidelines for clinical care.

Prophylactic administration of antibiotics can decrease postoperative morbidity, shorten hospitalization, and reduce the overall costs attributable to infections. Principles of prophylaxis include providing effective levels of antibiotics in the decisive interval, and, in most instances, limiting the course to intraoperative coverage only. Use in The National Research Council clean contaminated operations is appropriate and, in many instances, has been proven beneficial. Antibiotic prophylaxis is also indicated for clean operations, such as those involved with insertion of prosthetic devices, that are associated with low infection risk and high morbidity. Extension of antibiotic prophylaxis to other categories of clean wounds should be limited to patients with two or more risk factors established by criteria in the study of the efficacy of nosocomial infection control (SENIC) because the baseline infection rate in these patients is high enough to justify their use. Cefazolin (or cefoxitin when anaerobic coverage is necessary) remains the mainstay of prophylactic therapy. Selection of an alternate agent should be based on specific contraindications, local infection control surveillance data, and the results of clinical trials. Newer criteria for determining the risk of "site infection" (wound and intracavitary) are in evolution and may lead to modification of these recommendations over the next several years.

The Beirut terrorist bombing.

The Beirut terrorist bombing on October 23, 1983, caused 234 immediate deaths and injured at least 112 survivors. Military medical records were available for each casualty; postmortem examination reports were available for each immediate fatality. This represented a unique opportunity to assess type, incidence, treatment, and outcome of neurological injuries suffered in a mass casualty terrorist bombing situation. Three categories of neurological injuries are described: head injuries, spine and spinal cord injuries, and peripheral nerve injuries. The following types and numbers of injuries occurred among the 112 immediate survivors of the explosion: 37 head injuries--28 concussions, 20 scalp lacerations, 13 skull fractures, 6 facial bone fractures, 4 cerebral contusions, 5 dural lacerations, 2 cerebrospinal fluid fistulas, and 2 intracerebral hematomas; 2 spine or spinal cord injuries--1 cervical and 1 thoracolumbar spine fracture associated with neurological deficit; and 9 peripheral nerve injuries--1 facial nerve palsy, 2 brachial plexus palsies, 1 median and 1 radial nerve palsy, and 4 peroneal nerve palsies. Among 234 immediate fatalities, the types and numbers of neurological injuries were: 167 head injuries--93 scalp lacerations, 85 skull fractures, and 24 facial bone fractures; and 22 spine and spinal cord injuries--15 cervical and 7 thoracolumbar fractures. Seven of the 112 immediate survivors died; 4 of these deaths were related to severe head injuries. The treatment and outcome of survivors with neurological injuries is briefly described. One-third of the immediate survivors who suffered either a scalp laceration or a concussion had a concomitant skull fracture.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved survival rates of patients with acral lentiginous melanoma treated with hyperthermic isolation perfusion, wide excision, and regional lymphadenectomy.

Twenty-three patients with extremity malignant melanoma who fit the clinical and pathologic criteria for acral lentiginous melanoma were treated in a prospective, nonrandomized trial of wide local excision, regional lymphadenectomy, and hyperthermic isolation perfusion. There were 17 patients (73.9 percent) pathologically judged to be in stage I and 6 (26.1 percent) in stage II. Three patients entered the study with regional recurrence. Delay in diagnosis of the lesions averaged almost 3 1/2 years. Increasing awareness about the occurrence of acral lentiginous melanoma may result in earlier diagnosis, increased survival rates, and cure. Life table survival analysis revealed 5 and 10 year survival rates of 75 percent and 58 percent, respectively. This supports the findings of Krementz et al and suggests not only that a marked improvement in survival can be achieved through the use of hyperthermic isolation perfusion, but that the survival of patients with acral lentiginous melanoma is comparable with that of patients with other extremity malignant melanomas treated with aggressive multimodality therapy.

Telemedicine and pediatric surgery.

The practice of pediatric surgery has become increasingly demanding, requiring longer working hours with less reimbursement. Although manpower in this field is adequate, there are still areas that are underserved. Advances in technology offer the pediatric surgeon tools to improve efficiency of practice, cover wider areas of practice, and service underserved locations. The purpose of this report is to introduce the pediatric surgeon to telemedicine technology and its potential impact on the practice environment. The history, key components, and current applications of telemedicine are presented. The ability to integrate this technology in pediatric surgical practice holds great potential.

Evaluation of cis-platinum and DTIC combination chemotherapy in disseminated melanoma. A Southwest Oncology Group Study.

The development of disseminated melanoma is associated with an extremely poor prognosis. Use of a variety of chemotherapy agents alone and in combination has yielded response rates of only 10-30%. Surgery and radiation therapy play a useful role in palliative treatment, but have little or no value in the treatment of disseminated disease. In order to evaluate the response of disseminated malignant melanoma to combination chemotherapy with cis-platinum and 5-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide (DTIC), a phase II pilot study was developed and conducted at Oregon Health Sciences University. Thirty patients were treated from January 1983 to October 1986 and evaluated. There were two complete responses (7%) and nine partial responses (30%) for a total response rate of 37%. The median duration of response was 31 weeks. This response rate is higher than has been previously achieved with DTIC and cis-platinum, or with other drugs alone or in combination. Severe (grade 3) renal, neurologic, and hematologic toxicity was seen in four of 30, three of 30, and ten of 30 patients, respectively.

Antibiotic update for the surgeon.

Infection remains a significant source of morbidity and expense in the treatment of surgical patients there- fore, antibiotics continue to be an important part of the general surgeon's armamentarium. Unfortunately, physicians, and surgeons in particular, continue to order too many antibiotics too often, and for too long. Optimal use of antibiotics, as for any therapeutic modality, requires consideration of the risks and benefits as- sociated with available agents and regimens. Although the desired benefit is always successful eradication or avoidance of offending pathogens, the best way to acheive that goal may not be obvious. Decisions regarding choice of antimicrobial agent, duration of therapy, and route of administration are primarily based upon an- ticipation of clinical efficacy.

Effect of cooking on the nitrate levels in vegetables.

The effects on the nitrate content of vegetables exposed to boiling in water for various lengths of time is described. Whilst certain cultivars show a steady decrease in nitrate levels, other varieties show an initial rise. The nitrate content of the cooking water used shows a sustained increase as the cooking time is extended.