Hemorrhage and resuscitation induce delayed inflammation and pulmonary dysfunction in mice

BACKGROUND

It is well known that hemorrhagic shock induces inflammatory changes. Our objective was to study the histologic and biochemical changes in the lung and evaluate alterations in respiratory function after hemorrhage and resuscitation (H/R) in mice.

METHODS

After 30 min of hemorrhagic shock, mice were resuscitated with shed blood to restore mean arterial blood pressure to baseline. A sham group was anesthetized and instrumented for 30 min, but did not undergo hemorrhage. Myeloperoxidase (MPO) levels were measured and histologic analysis was performed on lung tissue. Pulmonary function was evaluated using whole-body plethysmography (WBP) 1, 3, and 5 days postprocedure. Alveolar function was evaluated by measuring carbon monoxide uptake via gas chromatography 5 days after H/R.

RESULTS

Five days after H/R, mice exposed to shock had significantly higher lung MPO levels and showed greater histologic evidence of lung injury. Airway resistance (Penh) in the sham mice was 0.91 +/- 0.06 versus 1.21 +/- 0.09 in the hemorrhage group (P < 0.01). Alveolar function was significantly decreased in the H/R group (70.8 +/- 3.6%) compared with shams (81.6 +/- 1.8%) (P < 0.05).

CONCLUSIONS

Hemorrhage and resuscitation cause delayed biochemical, histologic, and physiologic changes in the lung. These were marked by increased lung MPO, increased neutrophils, and decreased alveolar function. The alterations of pulmonary function and structure were most severe 5 days after H/R.

Photopolymers in orthopedics: characterization of novel crosslinked polyanhydrides

Novel, high modulus, degradable polymers were prepared from methacrylated anhydride monomers of tricarballylic acid (MTCA) and pyromellitylimidoalanine (MPMA-ala). Kinetic studies indicate that the time scale of photopolymerization of MTCA (< 30 s) is suitable for in vivo applications. Additionally, the tensile modulus of copolymers of these novel monomers with methacrylic anhydride (MA) ranged from 0.8 to 2.1 GPa, which lies between the modulus of trabecular and cortical bone. Degradation studies indicate that the copolymers of MTCA and MPMA-ala with MA are initially surface degrading, which is important to maintaining polymer strength through the degradation process. Monomers such as these that can be rapidly polymerized using ultraviolet or blue light into high modulus degradable materials have great potential in orthopedics.

Occult hypoperfusion is associated with increased morbidity in patients undergoing early femur fracture fixation

BACKGROUND

The presence of persistent occult hypoperfusion (OH) is associated with higher morbidity and mortality rates after trauma. Early femur fracture fixation in trauma patients with multiple injuries is associated with decreased morbidity and mortality. Association of OH and incidence of postoperative complications after intramedullary (IM) fixation in patients with femur fractures was investigated.

METHODS

A retrospective study design was used. All patients with femur fractures admitted to the trauma service of a Level I trauma center between January 1, 1995, and August 1, 1998, who were older than 18 years of age and who had IM fracture fixation within 24 hours of admission and serum lactate determinations on admission and at proscribed intervals, were included in the study. Patients with lactic acid levels > or = 2.5 mmol/L were determined to have OH. No patients had clinical signs of shock (hypotension, tachycardia, decreased urine output) on transfer to the operating room. Complete resuscitation was defined as a lactic acid level < 2.5 mmol/L. Patients were divided into two groups based on presence/absence of OH determined from the lactic acid level immediately before surgery. The incidence of all postoperative organ complications was recorded, and complication rates were compared between groups. Total hospital costs were also compared.

RESULTS

One hundred seventy-seven patients with femur fractures were admitted to the trauma service during this period. Seventy-nine patients met initial criteria for inclusion in the study. Further review excluded 32 patients. Occult hypoperfusion was present in 20 patients before early IM fixation (group 2). Twenty-seven patients were completely resuscitated before early IM fixation (group 1). Injury Severity Scores were similar in both groups. Group 2 had 35 complications in 20 patients, and group 1 had 11 complications in 27 patients. A significant difference was found in incidence of postoperative complications in group 1 (20%) versus group 2 (50%). Group 2 also had a significantly higher proportion of postoperative infections than group 1 (72% vs. 28%, respectively) and higher total hospital costs ($46,469 vs. $23,139).

CONCLUSION

The presence of OH in trauma patients undergoing early IM fixation of a femur fracture is associated with a twofold higher incidence of postoperative complications. Clinical judgment, not surgical dogma, should guide the timing of IM fixation in these patients. Identifying and correcting OH through relatively simple resuscitative measures may be advantageous in reducing morbidity in the patient with multiple injuries.

Persistent occult hypoperfusion is associated with a significant increase in infection rate and mortality in major trauma patients

OBJECTIVE

To investigate the hypothesis that occult hypoperfusion (OH) is associated with infectious episodes in major trauma patients.

METHODS

Data were collected prospectively on all adult trauma patients admitted to the Surgical/Trauma Intensive Care Unit from November of 1996 to December of 1998. Treatment was managed by a single physician according to a defined resuscitation protocol directed at correcting OH (lactic acid [LA] > 2.4 mmol/L).

RESULTS

Of a total of 381 consecutive patients, 118 never developed OH and 263 patients exhibited OH. Seventeen patients were excluded because their LA never corrected, and they all subsequently died. One hundred seventy-six infectious episodes occurred in 97 of the 364 patients remaining. The infection rate in patients with no elevation of LA was 13.6% (n = 118) compared with 12.7% (n = 110) in patients whose LA corrected by 12 hours, 40.5% (n = 79; p < 0.01 compared with all other groups) in patients whose LA corrected between 12 and 24 hours, and 65.9% (n = 57; p < 0.01 compared with all other groups) in patients who corrected after 24 hours. Among the patients with infections, there were 276 infection sites with 42% of infections involving the lung and 21% involving bacteremia. There was no difference in proportion of infections occurring at each site between groups. The mortality rate of patients who developed infections was 7.9% versus 1.9% in patients without infections (p < 0.05). Of the patients who developed infections, 69.8% versus 25.8% (p < 0.001) did not have their lactate levels normalized within 12 hours of emergency room admission. Logistic regression demonstrated that both the Injury Severity Score and OH > 12 hours were independently predictive of infection.

CONCLUSION

A clear increase in infections occurred in patients with OH whose lactate levels did not correct by 12 hours, with an associated increase in length of stay, days in surgical/trauma intensive care unit, hospital charges, and mortality.

Sodium nitroprusside mitigates oleic acid-induced acute lung injury

BACKGROUND

Acute lung injury (ALI) is associated with pulmonary hypertension, intrapulmonary shunting, and increased microvascular permeability, leading to altered oxygenation capacity. Oleic acid (OA) creates a significant ALI that physiologically mimics human adult respiratory distress syndrome (ARDS). It has been hypothesized that pulmonary vasodilatation may improve ALI. Studies in our laboratory using this model and nitric oxide (NO) have shown that NO inhalation is detrimental and worsens the effects of OA. We studied the effect of pretreatment with a potent vasodilator, sodium nitroprusside (SNP), on ALI induced by OA in an isolated lung model. We hypothesized that pretreatment with SNP will worsen pulmonary hypertension and oxygenation in OA-induced ALI, similar to the effects seen with inhaled NO in this model.

METHODS

Rabbit heart lung blocks were isolated, flushed in vivo, harvested, immediately perfused with whole blood, and ventilated with 50% oxygen. Pulmonary artery pressure was determined every 15 seconds for 90 minutes of perfusion. Oxygenation was determined by blood gas analysis of pulmonary venous effluent at 0, 20, 40, 60, and 90 minutes after initiation of OA infusion. Four groups were studied: saline control (SC), oleic acid control (OAC; 20-minute infusion of 50% OA/ethanol into pulmonary circulation), SNP control (NPC; 10 microg/ kg/min SNP infused without subsequent OA infusion), and SNP treatment (NPRx); 10 microg/kg/min SNP infused before OA/ethanol. Pulmonary artery pressure (PAP), oxygenation (arterio-venous oxygen difference [AVO2], compliance (CPL), and wet/dry lung weight were determined.

RESULTS

No significant differences were found between the NPRx group and SC. Pretreatment with SNP eliminated the detrimental effects of OA infusion.

CONCLUSIONS

Contrary to our hypothesis, pretreatment with SNP eliminates the decrease in oxygenation and increase in lung weight, and ameliorates pulmonary hypertension in our isolated lung model of OA-induced ALI.

High-frequency oscillatory ventilation can be effective as rescue therapy for refractory acute lung dysfunction

High-frequency oscillatory ventilation (HFOV) is a technique with limited use in adult patients. The main purpose of this pilot study was to evaluate HFOV on adult trauma patients with refractory lung dysfunction. Refractory lung dysfunction was defined as a PaO2:FiO2 ratio <75 for 1 hour despite maximum support via conventional mechanical ventilation (CMV). Five patients were placed on HFOV after failing CMV between May 1998 and December 1998. The mean PaO2:FiO2 ratio at the time of initiation (52.2+/-4.73) of HFOV increased significantly (P<0.05) by 2 hours (126.8 +21) and was still significantly increased (P<0.01) after 48 hours (181 +26.1) on HFOV. The mean airway pressures (MAPs) and peak pressures were significantly lower (P<0.01) after HFOV. The average MAP of the five patients was 34.6 +1.6 cm H2O at time zero and 25.2 cm H2O after 48 hours of HFOV. The mean peak pressure was 52.4 +3.0 cm H2O at time zero and was 35.8+/-3.01 after termination of HFOV. Survival was 80.0 per cent (four of five patients). In conclusion, all patients improved after initiation of HFOV, and HFOV should be considered in the treatment of patients with acute refractory lung dysfunction.

The golden hour and the silver day: detection and correction of occult hypoperfusion within 24 hours improves outcome from major trauma

BACKGROUND

The significance of occult hypoperfusion (OH) in the development of respiratory complications (RC), multiple system organ failure (MSOF), and death, and the effect of rapid identification and correction of OH in the severely injured trauma patient was investigated.

METHODS

A pilot retrospective study and the analysis of a prospective protocol to correct OH were performed. Pilot study: all trauma patients admitted to our Level I trauma center between February and December of 1995, who survived greater than 48 hours, had an Injury Severity Score greater than or equal to 20, and intensive care unit stays greater than 48 hours were evaluated. Prospective study: patients admitted between January 1, 1996, and April 30, 1997, who survived greater than 24 hours, with Injury Severity Score greater than or equal to 20, and who were hemodynamically stable (systolic blood pressure greater than 100, pulse rate less than 120, and urine output greater than 1 mL/kg per hour) were included. Serum lactic acid (LA) levels were measured at arrival and at proscribed intervals. In the pilot study, initial LA levels were examined in relation to outcome and complications. In the prospective study, patients with two consecutive LA levels greater than 2.5 mmol/L underwent invasive monitoring and vigorous resuscitation to correct their lactic acidosis.

RESULTS

Among the 31 patients studied in the pilot study, there were 4 deaths, 6 cases of MSOF, and 13 patients with RC. Lactic acidosis and poor cardiac performance, as evidenced by low cardiac index (CI) with normal filling pressures, were seen in all cases of MSOF and RC, as well as in all deaths. From these results, the prospective study was performed. Eighty-five intensive care unit patients met criteria for inclusion in the study. Six additional patients were excluded because of severe, untreatable intracranial hypertension at admission to the intensive care unit. Fifty-eight of these patients had OH in the first 24 hours. Forty-four patients corrected their OH within 24 hours with vigorous resuscitation. There were no deaths, three cases of MSOF, and 10 cases of RC in those patients who corrected OH within 24 hours. Persistent OH (>24 hours) was seen in 14 patients, despite resuscitative efforts, 43% of whom died. MSOF and RC were present in 36% and 50% of cases, respectively (p<0.05).

CONCLUSION

Initial lactic acidosis is associated with lower cardiac performance and higher morbidity and mortality. Persistent OH is associated with higher rates of RC, MSOF, and death after severe trauma. Early identification and aggressive resuscitation aimed at correcting continued elevation in serum lactate improves survival and reduces complications in severely injured trauma patients.

P-selectin and ICAM-1 mediate endotoxin-induced neutrophil recruitment and injury to the lung and liver

The role of leukocyte adhesion molecules in endotoxin-induced organ injury was evaluated by administering intraperitoneal Salmonella enteritidis lipopolysaccharide (LPS) to wild-type (WT) mice, P-selectin-deficient mice, intercellular adhesion molecule (ICAM)-1-deficient mice, and P-selectin-ICAM-1 double-mutant mice. In WT mice, there was a sevenfold increase in the number of neutrophils present in the pulmonary vascular lavage fluid, and there were sevenfold more intracapillary neutrophils by electron-microscopic (EM) morphometry at 4 h after intraperitoneal LPS compared with that in control mice. Extravascular albumin accumulation increased approximately twofold in the lungs and liver of WT mice treated with LPS. In the double-mutant mice, although overall mortality after intraperitoneal LPS was not attenuated, there was a significant delay in mortality in the P-selectin-ICAM-1-deficient mutants compared with that in WT mice after intraperitoneal LPS (P < 0.01). Moreover, compared with LPS-treated WT mice, lung and liver extravascular albumin accumulation was significantly lower in LPS-treated P-selectin-ICAM-1 double-mutant mice. Lung myeloperoxidase activity, normalized per 1,000 circulating neutrophils, increased after endotoxin in WT and P-selectin-deficient mice but not in P-selectin-ICAM-1 double-mutant mice. In addition, lung and liver myeloperoxidase activity per 1,000 circulating neutrophils in endotoxin-treated ICAM-1-deficient mice and P-selectin-ICAM-1 double mutants was significantly lower compared with that in endotoxin-treated WT mice. These data suggest that P-selectin and ICAM-1 significantly contribute to lung and liver injury after systemic endotoxemia.

Successful treatment of exsanguinating aortic injury from a fractured rib

A 57-year-old man presented in shock after a 15-foot fall from a ladder. A massive left hemothorax was present. He underwent prompt thoracotomy and was found to have a penetrating injury of the descending thoracic aorta caused by a fractured rib. Successful management of this type of aortic injury has not been previously reported.

Structural and functional consequences of alveolar cell recognition by CD8(+) T lymphocytes in experimental lung disease

CD8(+) T cells infiltrate the lung in many clinical conditions, particularly in interstitial lung disease. The role(s) that CD8(+) T cells might be playing in the pathogenesis of inflammatory lung disease is unclear at present, as is the direct contribution of CD8(+) T cell effector activities to lung injury. This report describes a transgenic model used to evaluate the impact, on respiratory structure and function, of CD8(+) T lymphocyte recognition of a target antigen expressed endogenously in alveolar epithelial cells. We found that adoptive transfer of cloned CD8(+) cytotoxic T lymphocytes (CTLs) specific for an alveolar neo-antigen (influenza hemagglutinin) leads to progressive lethal injury in transgenic mice, which dramatically affects lung structure and function. Transgenic recipients of CD8(+) CTLs exhibited tachypnea and progressive weight loss, becoming moribund over a period of several days. Concomitantly, the animals developed a progressive interstitial pneumonitis characterized initially by lymphocytic infiltration of alveolar walls and spaces, followed by an exuberant mononuclear cell infiltration that correlated with restrictive pulmonary mechanics and a progressive diffusion impairment. These results indicate that antigen-specific CD8(+) T cell recognition of an alveolar epithelial "autoantigen" is, in and of itself, sufficient to trigger an inflammatory cascade that results in the histological and physiological manifestations of interstitial pneumonia.

Outcome and cost of trauma among the elderly: a real-life model of a single-payer reimbursement system

BACKGROUND

As our population ages, the number of elderly trauma patients (age > or = 65 years) increases. Studies have demonstrated increased mortality and cost for a given injury severity in the elderly compared with younger patients. The financial viability of trauma centers in the United States has been an area of concern for many years. As reimbursement diminishes for privately insured patients, the ability to finance the care of the indigent is jeopardized. Medicare, the single-payer insurance plan for the elderly, reimburses at a lower rate than standard private insurance carriers. We examined the differences in outcome and cost between the elderly and younger patients and the financial burden imposed by care for elderly trauma. Our hypothesis was that elderly trauma patients would have poorer outcomes, higher cost, and generate greater financial losses than younger patients.

METHODS

All patients admitted to the University of Virginia Trauma Service from July 1, 1994, to July 1, 1997 were included. Trauma registry and patients records were examined. Patients with incomplete financial data (cost, reimbursement, and payer source) were excluded. Patients were grouped by age (18-64 and > or =65 years), Injury Severity Score, and payer source.

RESULTS

One thousand one hundred twenty-seven patients met the entry criteria. One hundred forty patients had incomplete financial or patient data and were excluded. Nine hundred eighty-seven patients were included in the study, of which 159 were elderly and 828 were 18 to 64 years of age. Injury Severity Scores were significantly higher in the elderly group. Only 2% of elderly patients were uninsured (76% were insured by Medicare), whereas 25% of younger patients were uninsured. Medicare reimbursement rates actually exceeded those of all other carriers (114% of costs). Elderly patients had a higher mortality rate, but the z score did not reach significance. The W score, however, indicated that there were more unexpected, negative outcomes among elderly patients. As injury severity increased, profit per case increased in the elderly and decreased in the younger group.

CONCLUSION

Despite higher injury severity and lower survival probability for the elderly, the length of hospital and intensive care unit stays, as well as the percentage of admissions to the intensive care unit, were similar. The per capita cost of hospital care for the elderly was lower than for younger patients, whereas reimbursement was higher, primarily because 98% of elderly patients were insured. Medicare, the single-payer insurance plan for the elderly, adequately reimburses for elderly trauma care. This implies that universal insurance coverage for all trauma patients would be desirable, even if reimbursement rates decreased significantly. The increased mortality in the elderly requires continued study and diligence.

A protocol for the initial management of unstable pelvic fractures

The initial management of life-threatening hemorrhage associated with severe pelvic fractures has long been a source of debate. A review of the literature reveals that many advocate emergent orthopedic external fixation (EX-FIX) for severe pelvic fractures, whereas others claim greater success with angiographic embolization (ANGIO) as the first line of treatment. Although many have attempted to classify management options by fracture pattern, to date there has been no prospective trial comparing outcomes for each method of treatment. We offer a prospective study of all pelvic fracture patients admitted to our Level I trauma center between July 1994 and July 1995. Patients were classified according to fracture pattern and degree of hemodynamic instability. Those with primarily anterior pelvic ring fractures underwent emergent EX-FIX for control of hemorrhage, whereas those with primarily posterior pelvic ring fractures underwent emergent ANGIO to control hemorrhage. We found that blood product requirements and hospital stay were similar in each group. However, the complication rate was higher in patients who underwent initial emergency EX-FIX, primarily because of failure to adequately control hemorrhage. We conclude that patients with anterior-posterior compression type 2 and 3, lateral compression type 2 and 3, or vertical shear injuries, who are hemodynamically unstable as a result of their pelvic fracture, should undergo immediate ANGIO if laparotomy is not indicated. If laparotomy is indicated, EX-FIX should be placed intraoperatively, followed by postoperative ANGIO.

Blunt splenic trauma: characteristics of patients requiring urgent laparotomy

In victims of blunt abdominal trauma, the spleen is the most common organ damaged, it is the most likely source of serious injury, and is associated with significant morbidity and mortality. The participants in this study were emergency department (ED) patients with splenic trauma determined via imaging study, surgical exploration, or autopsy. Patients were located using both the institution's trauma registry and discharge diagnoses (ICD-9 codes) involving splenic injury resulting from blunt trauma. Medical records including pre-hospital, ED, and hospital information were reviewed. Chi Square and Fisher's exact test were used for statistical analysis where appropriate, with a P value of less than 0.05 considered significant. Fifty-five patients (60% male) were analyzed with a mean age of 31 years (range, 1 to 78 years). Sixteen (30%) patients (mean age 44 years) were managed operatively, with 14 patients receiving only a diagnostic peritoneal lavage. All 38 patients (70%, mean age 26 years) who received nonoperative management were diagnosed by computed tomography. The motor vehicle crash represented the most frequent mechanism of injury in both groups; the nonoperative group, however, experienced other injury mechanisms more frequently. Clinical variables suggestive of the need for urgent surgical intervention (from ED to the surgical suite) include hypotension (systolic blood pressure less than 90 mm/Hg) in the pre-hospital setting or ED; tachycardia (heart rate greater than 100 beats/min) in the ED; abnormal hematocrit (less than 30) or coagulopathy (prothrombin time greater than 14 seconds) in the ED; multiple injuries; or blood transfusion in the ED. Complaints of pain resulting from traumatic injury and abdominal examination findings did not identify patients requiring urgent operative management. Hemodynamic instability, evidence of multiple injuries, abnormal laboratory parameters, and the requirement for blood transfusion in the ED identifies a patient population likely to require operative therapy of their splenic injury. Emergency physicians should consider early surgical consultation or urgent transfer to the regional trauma center in patients with these characteristics.

Nitric oxide potentiates acute lung injury in an isolated rabbit lung model

BACKGROUND

The effect of inhaled nitric oxide (NO) treatment on pulmonary function in the setting of adult respiratory distress syndrome is controversial. We examined the effect of inhaled NO on pulmonary function in an isolated rabbit lung model of oleic acid (OA)-induced acute lung injury. We hypothesized that NO would decrease pulmonary artery pressure and improve oxygenation.

METHODS

Rabbit heart-lung blocks were isolated, flushed in vivo, harvested, and immediately perfused with whole blood and ventilated with 50% oxygen (O2). Pulmonary artery pressure was determined every 15 seconds for 60 minutes of perfusion. Oxygenation was determined by blood gas analysis of pulmonary venous effluent at 0, 20, 40, and 60 minutes after initiation of OA infusion. Rabbits were randomized into four study groups: saline control; OA control, which received a 20-minute infusion of 50% OA/ethanol solution; NO treatment (20 ppm NO inhaled before OA infusion); and NO control, which underwent NO (20 ppm) pretreatment, followed by saline infusion. Pulmonary artery pressure, oxygenation (arteriovenous O2 difference), compliance, and wet/dry lung weight were determined.

RESULTS

Pretreatment with NO caused significant increases in pulmonary artery pressure (NO treatment versus NO control and saline control; no significant difference between NO treatment group and OA control group), and did not improve oxygenation in our model.

CONCLUSIONS

Contrary to our hypothesis, pretreatment with NO potentiates acute lung injury in our isolated lung model. There was significant exacerbation of pulmonary hypertension and no improvement in oxygenation. Further investigation of the possible deleterious effects of NO in acute lung injury are needed, especially in the early acute phases of this process.

Speed and efficiency in the resuscitation of blunt trauma patients with multiple injuries: the advantage of diagnostic peritoneal lavage over abdominal computerized tomography

BACKGROUND

The difference in speed, efficiency, and safety between diagnostic peritoneal lavage (DPL) and abdominal computerized tomography in the evaluation of adult blunt trauma patients with multiple injuries was investigated.

METHODS

A prospective protocol was analyzed. Adult blunt trauma patients admitted to a Level I trauma center in 1994 were examined. Registry and chart data were used. Patients admitted before the institution of the protocol (January 1-June 30, 1994) were compared with those admitted afterward (July 1-December 31, 1994). Time spent in the emergency department before definitive placement or surgical intervention was studied.

RESULTS

Patients in the second period, when DPL was used more frequently, spent significantly less time in the emergency department and radiology. No missed injuries were identified in either group. The percentages of nontherapeutic laparotomies were similar between the two groups. Cost was significantly lower in the group that underwent DPL.

CONCLUSION

Patients with severe head injury, open fractures, or any evidence of hemodynamic instability are better served by DPL as the primary diagnostic modality. Its sensitivity and specificity are equivalent to those of computerized tomography; this facilitates evaluation and allows for simultaneous procedures and quicker initiation of definitive treatment.

Interhospital versus direct scene transfer of major trauma patients in a rural trauma system

The purpose of organized trauma systems is to ensure the expeditious transfer of seriously injured patients to the facility best equipped to care for their injuries. Patients are referred to our trauma center, either by ambulance or helicopter, directly from the scene or through interhospital transfer. We examined the difference in outcome between those patients sent directly to the trauma center versus those seen at other hospitals and subsequently referred to the trauma center. Our hypothesis was that a delay at the referring hospital is detrimental to patient outcome. Adult trauma patients with Injury Severity Scores > 15, treated over 16 months from July 1, 1994, to October 31, 1995, were studied. Patients who survived 24 hours experienced significantly shorter intensive care unit (14 vs 10 days; P < 0.05) and hospital (21 vs 16 days; P < 0.05) lengths of stay when taken directly to the trauma center. In addition, there were significantly fewer deaths in patients with a probability of survival > 0.5 and a slightly lower overall mortality in those patients who survived at least 1 day. This study demonstrates that patients with major trauma taken directly to the trauma center had shorter hospital and intensive care unit stays and lower mortality. The study supports the paradigm that, when possible, major trauma patients should be sent to trauma centers directly from the injury scene.

HIV and medical nutrition therapy

In those who are infected with human immunodeficiency virus, poor nutritional status can result from numerous causes, including anorexia, catabolism, chronic infection, fever, poor nutrient intake, nausea, vomiting, diarrhea, malabsorption, metabolic disturbances, lack of access to food, depression, and side effects of drug, radiation, and chemotherapy treatments. A compromised immune system may not be reversed by any medical treatments at this time, but malnutrition may be prevented and reversed by using current therapies, including medical nutrition therapy that includes nutrition assessment, the development of an individualized nutrition therapy plan, and implementation of the therapy. There is substantial evidence that medical nutrition therapy saves lives, reduces morbidity, improves health outcomes, reduces costs, and shortens hospital stays.

Postinjury thromboxane receptor blockade ameliorates acute lung injury

BACKGROUND

Acute lung injury is associated with pulmonary hypertension, intrapulmonary shunting, and increased microvascular permeability, leading to altered oxygenation capacity. Thromboxane A2 has been found to be a central mediator in the development of septic and oleic acid (OA)-induced acute lung injury. Our previous study demonstrated a beneficial effect of preinjury thromboxane A2 receptor blockade. The current study examines the efficacy of postinjury receptor blockade on oxygenation capacity and pulmonary hemodynamics in an isolated lung model of OA-induced acute lung injury.

METHODS

Four groups of rabbit heart-lung preparations were studied for 60 minutes in an ex vivo perfusion-ventilation system. Saline control lungs received saline solution during the first 20 minutes of study. Injury control lungs received an OA-ethanol solution during the first 20 minutes. Two treatment groups were used: T10, in which the thromboxane receptor antagonist, SQ30741, was infused 10 minutes after the initiation of OA infusion; and T30, in which the thromboxane receptor antagonist was infused 30 minutes after OA infusion.

RESULTS

Significant differences were found in oxygenation (oxygen tension in T10 = 62.6 +/- 11.7 mm Hg, T30 = 68.2 +/- 21.2 mm Hg; injury control = 40.2 +/- 9.0 mm Hg, saline control = 123.5 +/- 16.01 mm Hg; p < 0.001) and percentile change in pulmonary artery pressure (T10 = 1.1% +/- 19.4% increase, T30 = 11.2% +/- 7.3% increase; injury control = 47.6% +/- 20.5%, saline control = 4.2% +/- 6.81%; p < 0.001).

CONCLUSIONS

This study demonstrates that blockade of the thromboxane A2 receptor, even after the initiation of acute lung injury, eliminates pulmonary hypertension and improves oxygenation.

Psoas abscess with sepsis mimicking traumatic hemorrhagic shock after a fall

Abscess of the psoas muscle is infrequently encountered. An infectious emergency of this type usually presents in a nonspecific manner and thus poses a significant diagnostic challenge to the emergency physician. Diagnosis and specific treatment are often delayed, which can lead to increased mortality. This case report presents a patient with altered mental status and hypotension after a fall, who was initially managed as a trauma victim. Emergency department evaluation initially focused on a traumatic etiology of the above abnormalities. Subsequent assessment determined that the patient's condition was due to an underlying psoas abscess with sepsis. Appropriate anatomy, clinical presentation, and management are discussed in hopes of increasing physician awareness of this uncommon infectious condition.

The effect of oxygen delivery-directed resuscitation on splanchnic and hepatic oxygen transport after hemorrhagic shock

BACKGROUND

Gut and hepatic dysfunction, during and after hypovolemic shock, have been implicated as causative mechanisms in the development of multiple system organ failure in the trauma patient. Current techniques of assessment of perfusion only detect changes in systemic oxygen transport. We designed an animal model that can measure changes in oxygen transport in the liver and gut during hypovolemic shock and resuscitation.

MATERIALS AND METHODS

Animals were hemorrhaged to a mean arterial pressure (MAP) of 60 mm Hg and maintained at 60 mm Hg for 60 min. Animals were then assigned to one of three groups. Group I served as nontreatment controls. Group II received shed blood and saline in sufficient volumes to restore MAP to baseline. Group III animals were resuscitated with shed blood, saline, and donor blood to restore systemic oxygen delivery to the preshock value.

RESULTS

The animals resuscitated to their baseline systemic oxygen delivery, Group III, had significantly higher systemic, hepatic, and splanchnic oxygen delivery than the remaining groups. In addition, Group III had higher oxygen consumption, portal flow, and hepatic artery flow than the blood pressure-directed group, Group II. The decrease in oxygen extraction ratio in the gut and liver was significantly greater in Group III than in Group II.

CONCLUSIONS

These data show that hepatic and gut vascular beds are better perfused when resuscitation from hemorrhage is guided by systemic oxygen transport measurements compared to resuscitation guided by blood pressure.

Management of hepatic artery injury: case report

The trauma surgeon encounters hepatic arterial injury only rarely. The majority of these injuries appear to be due to penetrating trauma, with few cases of hepatic artery injury secondary to blunt trauma reported in the literature. In the setting of blunt trauma, hepatic artery injury is generally accompanied by other severe injuries, and mortality remains high. We present two patients who sustained an avulsion of the left hepatic artery complicating severe blunt trauma to the abdomen and pelvis. Surgical management included ligation of the involved vessel. Both patients required management in the intensive care unit, one eventually succumbing to multisystem organ failure. The cases highlight management principles in these injuries, and treatment options are discussed.

Asynchronous bilateral medullary carcinoma of the breast

We report a case of bilateral medullary carcinoma of the breast occurring asynchronously in a young woman and review the epidemiology of this form of breast cancer. Clinical and radiographic surveillance are necessary in the follow-up of all women with medullary carcinoma of the breast to ensure that further disease is detected rapidly and treated properly.

Coagulopathy in severe closed head injury: is empiric therapy warranted?

Closed head injuries account for a significant portion of the morbidity and mortality following blunt trauma. Severe closed head injuries can be complicated by the development of a coagulopathy that may worsen blood loss and delay invasive neurosurgical procedures. Awaiting the results of coagulation studies prior to initiating treatment of such a coagulopathy introduces an inherent delay that may allow worsening of the coagulation disturbance and negatively influence outcome. This study was undertaken to see if a subgroup of patients with severe closed head injuries had a high probability of developing a coagulopathy and would warrant empiric treatment with fresh frozen plasma. The records of adult patients admitted to our trauma center with a Glasgow coma score (GCS) of < or = 8 and an extracranial abbreviated injury score of < or = 2 during a 9-month period were reviewed. Patients with penetrating trauma or whose altered level of consciousness was due to sedation or shock were excluded. The presence of coagulation abnormalities was determined according to prothrombin time and partial thromboplastin time obtained on admission. The time to invasive neurosurgical procedures for both coagulopathic and noncoagulopathic patients was determined as well as the mean number of hospital days, intensive care unit days, and the mortality for each group. Eighty-one per cent of the patients with a GCS < or = 6 were coagulopathic on admission, and all patients with a GCS of 3 or 4 were coagulopathic. In contrast, no patient with a score of 7 or 8 was coagulopathic. The coagulopathic patients tended to have a higher mortality than the noncoagulopathic patients (53 versus 22%) as well as longer intensive care unit and hospital stays. The mean time to neurosurgical intervention for the coagulopathic group was 226.0 +/- 190.9 minutes versus 84.8 +/- 38.4 minutes for the noncoagulopathic patients. We conclude that patients with closed head injuries who present with a GCS of 6 or less are candidates for empiric treatment for coagulopathy. Such treatment will negate the delay of awaiting coagulation studies. Whether or not such therapy shortens the interval between admission and neurosurgical procedures or alters outcome will require prospective study.

Presentation of Ehlers-Danlos syndrome: iliac artery pseudoaneurysm rupture

We present a case of acute flank and groin pain resulting from a ruptured left iliac artery with pseudoaneurysm in a patient with previously undiagnosed Ehlers-Danlos syndrome (EDS). EDS is an uncommon, heterogeneous disease of abnormal collagen production with potentially fatal sequelae. The nine major types of EDS have varying clinical manifestations and degrees of severity. Type IV EDS is of special concern in that it is frequently associated with life-threatening vascular complications such as arterial aneurysm formation with rupture and dissection. EDS should be suspected in young people with vascular complications, recurrent joint dislocations, or fragile skin. In patients with known EDS, abdominal, flank, or pelvic pain should be investigated promptly to rule out life-threatening complications involving the vascular system, gastrointestinal tract, or gravid uterus.

Thromboxane receptor blockade improves oxygenation in an experimental model of acute lung injury

BACKGROUND

Adult respiratory distress syndrome remains a major cause of morbidity and mortality. We investigated the role of thromboxane receptor antagonism in an experimental model of acute lung injury that mimics adult respiratory distress syndrome.

METHODS

Three groups of rabbit heart-lung preparations were studied for 30 minutes in an ex vivo blood perfusion/ventilation system. Saline control (SC) lungs received saline solution during the first 20 minutes of study. Injury control (IC) lungs received an oleic acid-ethanol solution during the first 20 minutes. Thromboxane receptor blockade (TRB) lungs received the same injury as IC lungs, but a thromboxane receptor antagonist (SQ30741) was added to the blood perfusate just prior to study. Blood gases were obtained at 10-minute intervals, and tidal volume, pulmonary artery pressure, and lung weight were continuously recorded. Oxygenation was assessed by measuring the percent change in oxygen tension over the 30-minute study period. Tissue samples were collected from all lungs for histologic evaluation.

RESULTS

Significant differences were found between SC and IC lungs as well as TRB and IC lungs when comparing pulmonary artery pressure (SC = 33.1 +/- 2.2 mm Hg, TRB = 35.4 +/- 2.1 mm Hg, IC = 60.4 +/- 11.1 mm Hg; p < 0.02) and percent change in oxygenation (SC = -20.6% +/- 10.3%, TRB = -24.2% +/- 9.5%, IC = -57.1% +/- 6.2%; p < 0.03). None of the other variables demonstrated significant differences.

CONCLUSIONS

Thromboxane receptor blockade prevents the pulmonary hypertension and the decline in oxygenation seen in an experimental model of acute lung injury that mimics adult respiratory distress syndrome.

A novel method for replacement of the dislodged tracheostomy tube: the nasogastric tube "guidewire" technique

Unscheduled replacement of dislodged tracheostomy tubes can be a challenging procedure for the physician and a frightening event for the patient. Forceful attempts at replacement are both painful and dangerous; such attempts may disrupt the soft tissues adjacent to the tracheostomy tract, creating a false passage and potentiating acute respiratory failure. We describe a technique using a standard nasogastric tube that allows safe and precise replacement of tracheostomy tubes in both sedated and combative patients under routine and emergent conditions.

Does oxygen delivery-directed resuscitation worsen outcome of head injured patients with multisystem injuries?

There is concern that oxygen delivery-directed resuscitation in patients with multiple trauma, including severe head injury, may worsen neurologic recovery. To study this, we retrospectively examined 31 patients admitted over an 18-month period who met the inclusion criteria of having suffered blunt trauma, were between 15 and 65 years of age, had an admission Glasgow coma scale of < or = 8, intact corneal and gag reflexes, and extracranial injury with an Abbreviated Injury score of > or = 3. All patients were placed on intracranial pressure monitors. In comparing the 14 patients whose resuscitation was guided by oxygen delivery (DO2) with the 17 who were resuscitated by standard fluid restriction (FR), we found that despite the DO2 group's having received a significantly greater volume of resuscitation fluids in the first 48 hours after injury, there was no difference in the neurologic recovery between the two groups.

Anterior lung herniation: another aspect of the seatbelt syndrome

Shoulder harnesses can be a source of thoracic injury in motor vehicle crashes. Sternal and rib fractures are most commonly reported. We present a case of a traumatic anterior lung herniation secondary to shoulder harness trauma in a motor vehicle crash victim with multiple injuries. A brief review of lung hernias is provided as well as a brief discussion of the thoracic manifestations of the seatbelt syndrome.

Use of the inferior epigastric artery to revascularize a lower pole renal artery in renal transplant

The increasing use of living-related donors has increased the incidence wherein the transplant surgeon is required to use special vascular surgical techniques to transplant kidneys with anomalous arterial anatomy. One of the most commonly encountered arterial anomalies is the presence of a lower pole renal artery. In many cases, this artery can be anastomosed to the main renal artery, and the main renal artery can then be anastomosed into the recipient vessel. However, there are cases where the lower pole renal artery is too distant from the main renal artery to allow an anastomosis to be performed. The lower pole renal artery of the graft must be revascularized to avoid ischemic injury to the ureter. Thus, alternate methods for the revascularization of this vessel must be found. We describe the use of the recipient inferior epigastric artery as an arterial supply for the donor lower pole artery. In our case report, this method provided excellent flow to the lower kidney and was documented by later studies.

Nonoperative management of blunt hepatic trauma: the exception or the rule?

To evaluate the role of nonoperative management in the treatment of blunt liver trauma we examined all victims of blunt hepatic trauma admitted to our institution during a 36-month period under a protocol of nonoperative management. One hundred twenty-six patients had the diagnosis of blunt hepatic injury confirmed by abdominal computed tomographic (CT) scanning, surgical exploration, or autopsy. Twenty-four patients went to the operating room without CT scanning because of hemodynamic instability (16), peritoneal signs (two), or positive results on DPL (six). Ten other patients died of extra-abdominal trauma before reaching the operating room. The remaining 92 patients had CT scans of the abdomen. Of these 92 patients, 20 required surgery. The indications for surgery were hemodynamic instability (seven), peritoneal signs (six), nonhepatic injuries requiring surgery (five), and massive hemoperitoneum (two). Seventy-two patients were intentionally managed nonoperatively (55% of total liver injuries, 78% of scanned patients). Seventy (97%) of these patients were managed successfully without surgery. Of these 72 liver injuries, 11 were grade I, 28 were grade II, 16 were grade III, ten were grade IV, and five were grade V. The transfusion requirement in the first 24 hours for the nonoperative group was significantly lower than that for the group undergoing surgery (1.2 +/- 1.7 vs. 12.2 +/- 14 units). There were no instances of hemobilia, intrahepatic bile collections, or abdominal abscess in the nonoperative group. The grade of hepatic injury as diagnosed by CT scan does not predict the need for surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

A new technique for repair of large ventral hernias using the "starburst" mesh closure technique

Large ventral hernias are extremely difficult surgical problems, especially in the obese population. Any such hernias with diameters greater than 15 cm are especially prone to significant operative morbidity and high recurrence rates. We report a new technique of mesh closure that has resulted in no morbidity and no recurrences in this high-risk population. Seven patients with large ventral hernias (> 15 cm in diameter) have undergone this new procedure. Three patients required a preoperative establishment of a pneumoperitoneum to increase abdominal domain. A piece of Marlex mesh is fashioned with spokes 2 cm x 10 cm radiating from the central area of the mesh. The central area is sewn to the fascia with a running circumferential suture, and the spokes are then brought out from beneath the fascia, extending approximately 7.5 cm from the edge. The spokes are secured to the fascia at their exit points and then are again secured toward the center of the mesh. Over follow-up periods ranging from 6 months to 4 years, no recurrences or infections have occurred in these seven patients.

Duodenectomy and reimplantation of the ampulla of Vater for megaduodenum

After several unsuccessful surgical procedures, a case of megaduodenum in a 29-year-old woman was treated successful with duodenal resection and reimplantation of the ampulla with a Roux en Y limb of jejunum. Alternate approaches to this complicated condition are discussed.

Femoral catheters and deep venous thrombosis: a prospective evaluation with venous duplex sonography

Femoral vein cannulation (FVC) with 8.5F Swan-Ganz catheter introducers allows expeditious intravenous access and rapid volume infusion; however, the incidence of associated iliofemoral deep venous thrombosis (DVT) is unknown. Trauma patients (n = 76) requiring unilateral FVC were prospectively entered into a study where they were resuscitated via FVC and serially evaluated with bilateral venous duplex sonography (VDS). The incidence of DVT in catheterized femoral veins was compared with that in uncatheterized femoral veins. Catheters were removed promptly and VDS was performed within 24 hours and weekly for 1 month. Iliofemoral DVTs were identified in 11 of the 76 patients (14%). Iliofemoral DVTs occurred on the cannulated side in 9 (81.8%) compared with 2 (18.2%) on the uncannulated side (p < 0.05). We conclude that the use of the 8.5F FVC is associated with an increased incidence of DVT and that despite its convenience, this technique should not be routine.

Renal vasodilation with acetylcholine but not secretin increases nonnutrient blood flow

To investigate the fact that, despite its renal vasodilator properties, acetylcholine (ACh) provides no protection against acute renal failure, we measured nutrient (NBF) and nonnutrient renal blood flow (NNBF) during ACh infusion. The effect of ACh and secretin on NBF in the outer and inner cortex and outer medulla using 133Xenon (133Xe) washout with freeze dissection analysis was determined. We then calculated NNBF as the difference between NBF in the entire cortex and outer medulla (133Xe washout) and total renal blood flow (TRBF) measured by electromagnetic flow probe. NNBF was also assessed from the 86Rubidium (86Rb) recovery after administration into the renal artery. ACh increased TRBF without increasing NBF, resulting in an increased calculated NNBF. ACh, but not secretin, increased NNBF in the kidney as measured with 86Rb. Thus we conclude that ACh selectively induces a large increase in NNBF in the kidney.

Acoustic neuroma: postoperative vertigo and the mechanisms of compensation

Ninety-five percent of patients with acoustic neuroma experience some degree of vertigo preoperatively, postoperatively or both. Postoperative vertigo is often a debilitating condition that results when the eighth cranial nerve is severed during surgery to resect a tumor growing around the vestibular portion of this nerve. Thus, surgery for acoustic neuroma affects the membranous labyrinth, which is the functional part of the vestibular apparatus and is primarily concerned with equilibrium. Compensation for impaired equilibrium may be by biofeedback in the vestibular pathways, visual control, exercise or drug therapy. Nurses can significantly influence the recovery of acoustic neuroma patients by encouraging and reinforcing exercise and other mechanisms of vestibular compensation.

Initial experience with laparoscopic surgery: establishing a new surgical procedure

Laparoscopic surgery impacted the surgical world in the United States in 1990. This report reviews the initial experience of 34 surgeons in 8 teaching hospitals of the Northeastern Ohio Universities College of Medicine. There were 538 cases reported from May 1, 1990 to January 31, 1991. There was no mortality and the morbidity rate was 4.8%, including three bile duct injuries. The conversion rate to an open procedure was 6.1%. The criteria for credentialing, training, and resident and faculty education are included. The data reported by the Surgery Department of Northeastern Ohio Universities College of Medicine are very similar to reported series from the current literature.

Cochlear IgG in the C3H/lpr autoimmune strain mouse

The inner ear of the C3H/lpr autoimmune strain mouse was evaluated to identify potential mechanisms by which systemic autoimmune disease interferes with auditory function. The inner ears were immunohistochemically stained for IgG at ages before (2 months) and after (6-10 months) autoimmune disease onset and compared to age-matched nonautoimmune C3H/HeJ controls. Immunoreactivity for IgG was not seen in the 2 month C3H/lpr autoimmune mice or in either age group of the C3H/HeJ controls. On the other hand, all older C3H/lpr mice showed reaction product in the vessels of the cochlea, particularly the stria vascularis and bony capsule. Less frequent sites of staining were the geniculate ganglion, marrow cavities of the bony capsule, tensor tympani muscle, and on one occasion, a hair cell of the organ of Corti. These findings indicate that IgG is widespread within the cochlea and its vessels during systemic autoimmune disease and not directed against any specific sensorineural structure. This suggests a generalized or indirect mechanism whereby such systemic disease affects the inner ear.

Endothelial-dependent and -independent responses in the thoracic aorta during endotoxic shock

Endotoxic shock is characterized by a variety of hemodynamic disturbances which result in tissue hypoperfusion. There is some evidence for endothelial damage caused by endotoxin. The present study addressed the hypothesis that vascular responsiveness to endothelial-dependent vasodilators is altered in endotoxic shock. Dose-response relationships for an endothelial-dependent vasodilator, acetylcholine, and an endothelial-independent vasodilator, adenosine, were determined in guinea pig aortic rings. Rings were examined from either control (untreated) animals or from animals given Escherichia coli endotoxin (4 mg/kg, i.p.) 16 hr prior to functional studies. Dose-response relationships to adenosine were similar in aortic rings from control and shocked animals. However, response to acetylcholine were attenuated by 30% (P less than .05) in the shocked group. To distinguish between a direct, acute effect of endotoxin versus effects produced by systemic changes that occur during shock, rings were isolated from untreated animals and incubated with endotoxin in vitro for 30 min prior to and during dose-response measurements. Incubation with endotoxin caused no change in aortic responses to adenosine or acetylcholine. Electron microscopy revealed a separation of the endothelium from the internal elastic lamina and an increase in inter-endothelial gaps in rings isolated from shocked animals. These structural changes were not observed in rings from untreated animals or in rings incubated with endotoxin in vitro. We conclude that endothelial-dependent vasodilation is attenuated during endotoxic shock. The functional changes are correlated with ultrastructural alterations of the endothelium.

Hemodynamic and renal advantages of dual cyclooxygenase and leukotriene blockade during canine endotoxic shock

The decline in mean arterial pressure (MAP), cardiac output (CQ), and renal blood flow (RBF) that accompany endotoxic shock is partly ameliorated by cyclooxygenase or leukotriene blockade. This study determined whether dual cyclooxygenase and leukotriene blockade provided greater hemodynamic protection than either single blockade alone. Mongrel dogs were pretreated with either ibuprofen or LY171883 alone or dual blockade consisting of ibuprofen combined with LY171883 or propylgallate, then given Escherichia coli endotoxin, and monitored for 10 hr. Postendotoxemic MAP was equally maintained with dual blockade and with ibuprofen. For the first 5 hr postendotoxin, CQ was best maintained by dual blockade. However, by 9 hr postendotoxin, CQ in LY171883-treated animals was 88 +/- 8% of control. LY171883 provided the greatest protection of RBF, while dual blockade provided the least protection for both RBF and urine flow rates (V). Ibuprofen-treated dogs required less NaHCO3 for acid-base maintenance than did dual-blocked animals. In summary, dual cyclooxygenase and leukotriene blockade was advantageous in protecting MAP and CQ during the early phases of shock but provided no greater protection of RBF, GFR, V or acid-base balance than did single blockade. Overall, LY171883 provided the best protection from circulatory dysfunction.

Nutrient and nonnutrient renal blood flow

The role of prostaglandins in the distribution of total renal blood flow (TRBF) between nutrient and nonnutrient compartments was investigated in anesthetized mongrel dogs. Renal blood flow distribution was assessed by the xenon 133 freeze-dissection technique and by rubidium 86 extraction after ibuprofen treatment. Ibuprofen (13 mg/kg) significantly decreased TRBF by 16.3% +/- 1.2% (mean +/- SEM electromagnetic flow probe; p less than 0.005), but did not alter blood flows to the outer cortex (3.7 vs 4.3 ml/min per gram), the inner cortex (2.6 vs 2.7 ml/min per gram), and the other medulla (1.5 vs 1.5 ml/min per gram), which suggests a decrease in nonnutrient flow. In a separate group of animals the effect of reduced blood flow on the nutrient and nonnutrient components was determined by mechanically reducing renal arterial blood flow by 48%. Unlike the ibuprofen group, nutrient blood flows were proportionally reduced with the mechanical decrease in TRBF in the outer cortex (1.9 ml/min per gram, p less than 0.05), the inner cortex (1.4 ml/min per gram, p less than 0.05), and the outer medulla (0.8 ml/min per gram, p less than 0.01). These results indicate no shift between nutrient and nonnutrient compartments. Nutrient and nonnutrient renal blood flows of the left kidney were also determined by 86Rb extraction. After ibuprofen treatment, nonextracted 86Rb decreased to 12.1% from the control value of 15.6% (p less than 0.05). Mechanical reduction of TRBF did not significantly decrease the proportion of unextracted 86Rb (18.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Development of minocycline containing polycaprolactone film as a local drug delivery]

Local drug delivery by using biocompatible polymers has been developed in the treatment of periodontitis for many years. The purpose of this study was to examine the release kinetics of minocycline from monolithic film prepared from polycaprolactone and polyethylene glycol and to examine the antimicrobial activity in vitro. Polycaprolactone (Mwt 60,000), polyethylene glycol and minocyline was dissolved by chloroform, which was vigorously stirred for 24 hours and it was dried in vacuum chamber. The thickness of cast films containing 20%, 30% and 40% minocycline was 200 +/- 10 microns. Release rate of minocycline from the film was measured by means of a UV spectrophotometer. In vitro releasing test, each film showed a large burst effect within first two and three hours and a steady state release kinetic at the rate of 4-8 micrograms/cm/hour for 7 days. In antimicrobial test, each sample (one fourth inch in diameter) sunk in the broth that had been innoculated with periodontopathic bacteria showed growth inhibitory activity after 48 hr anaerobic incubation. In cytotoxicity test, there was no significant cytotoxic effect in casting film to human gingival fibroblast. This study showed that, by embedding minocycline in polycaprolactone, it is feasible to obtain substained release of the drug within the periodontal pocket for seven days and should be useful tool for elimination of pathogenic microflora from periodontal pocket or reducing inflammation in periodontal disease.

Potentiation of noise induced threshold shifts and hair cell loss by carbon monoxide

Previous studies have determined that severe systemic hypoxia disrupts cochlear function acutely, but have suggested that augmentation of cochlear perfusion may successfully protect cochlear function under all but the most profound hypoxic treatments. In the current study we report on the chronic effects of simultaneous exposures to noise and carbon monoxide on pure tone thresholds and hair cell survival in rats. Following initial threshold determination, rats received acute exposure to carbon monoxide, noise, or both agents concurrently. Thresholds were evaluated 2-4 and 6-8 weeks later. The data show that carbon monoxide alone does not affect either auditory thresholds or compromise hair cells at the light microscopic level. The noise exposure alone produced variable, but quite limited permanent threshold shifts which were related to the power spectrum of the broad band noise that was employed. Hair cell loss was restricted to the basal turn of the cochlea. Simultaneous exposure to carbon monoxide and noise induced large threshold shifts at all frequencies studied, but the effect was greatest at the highest test frequency; an effect not consistent with the noise power spectrum. Widespread hair cell loss persisted over fully half of the basilar membrane in the most severely affected rat. Outer hair cells appear to be particularly vulnerable. Carbon monoxide plus noise did not appear to preferentially disrupt a particular row of outer hair cells. These data complement existing evidence that hyperoxia can mitigate against noise induced injury and reinforce the view that some types of noise induced damage may result from metabolic insufficiencies.

Immunological relatedness of annelid extracellular hemoglobins and chlorocruorins

1. The immunological relatedness of several annelid extracellular hemoglobins and chlorocruorins was investigated using ELISAs and Western blotting to determine the binding of purine polyclonal and monoclonal antibodies to Lumbricus terrestris hemoglobin with the hemoglobins of Tubifex tubifex, Tylorrhynchus heterochaetus, Arenicola marina and Macrobdella decora and the chlorocruoins of Myxicola infundibulum and Eudistylia vancouverii. 2. Polyclonal antibodies to Lumbricus terrestris hemoglobin bound to all the other hemoglobins and chlorocruorins. However, the titers were in all cases one to several orders of magnitude smaller than with Lumbricus terrestris hemoglobin. 3. Polyclonal antibodies to Eudistylia vancouverii chlorocruorin bound to the hemoglobins of Lumbricus terrestris, Tubifex tubifex, Arenicola marina, Tylorrhynchus heterochaetus and Macrobdella decora. 4. Of the nine monoclonal antibodies to Lumbricus terrestris hemoglobin isolated, two (No. 24 and No. 26) bound to the other hemoglobins and to Myxicola chlorocruorin, but the binding was again weaker than with Lumbricus hemoglobin. Antibody No. 26 also bound to Eudistylia chlorocruorin. Although antibody No. 24 appears to recognize a conformation-dependent epitope, antibody No. 26 recognizes a common epitope in each of the four subunits M, D1, D2, and T of unreduced Lumbricus hemoglobin. 4. An additional two monoclonal antibodies to Lumbricus hemoglobin (No. 21 and No. 25) bound also only to Tubifex hemoglobin. Antibody No. 21 recognizes subunits D1 and M of Lumbricus hemoglobin and No. 25 appears to recognize a conformation-dependent epitope.