Clinical Diagnosis of Infection in Surgical Intensive Care Unit: You're Not as Good as You Think!

Background: Because of the everincreasing costs and the complexity of institutional medical reimbursement policies, the necessity for extensive laboratory work-up of potentially infected patients has come into question. We hypothesized that intensivists are able to differentiate between infected and non-infected patients clinically, without the need to pan-culture, and are able to identify the location of the infection clinically in order to administer timely and appropriate treatment. Methods: Data collected prospectively on critically ill patients suspected of having an infection in the surgical intensive care unit (SICU) was obtained over a six-month period in a single tertiary academic medical center. Objective evidence of infection derived from laboratory or imaging data was compared with the subjective answers of the three most senior physicians' clinical diagnoses. Results: Thirty-nine critically ill surgical patients received 52 work-ups for suspected infections on the basis of signs and symptoms (e.g., fever, altered mental status). Thirty patients were found to be infected. Clinical diagnosis differentiated infected and non-infected patients with only 61.5% accuracy (sensitivity 60.3%; specificity 64.4%; p = 0.0049). Concordance between physicians was poor (κ = 0.33). Providers were able to predict the infectious source correctly only 60% of the time. Utilization of culture/objective data and SICU antibiotic protocols led to overall 78% appropriate initiation of antibiotics compared with 48% when treatment was based on clinical evaluation alone. Conclusion: Clinical diagnosis of infection is difficult, inaccurate, and unreliable in the absence of culture and sensitivity data. Infection suspected on the basis of signs and symptoms should be confirmed via objective and thorough work-up.

Investigating Clinical and Cost Burdens of Law Enforcement–Related K9 Injuries: The Impact of “the Bite” on a Community Hospital

The decision to introduce canines (K9s) to a law enforcement (LE) agency does not typically involve the evaluation of the fiscal or clinical impact on local hospitals. This study compared injury, cost, and care associated with K9s to a common nonlethal force method, the Thomas A Swift Electrical Rifle (TASER), to highlight the cost and resources required to treat both patient types. Patients treated for LE-related K9 and TASER injuries at a Level I community-based trauma center (2011–2016) were evaluated for level of care required (e.g., surgeon/specialist), clinical interventions, proxy medical costs, and length of stay (LOS). Nearly one-third of K9 patients required tertiary-level medical care. The cost of treating the K9-inflicted injuries (n = 75) was almost twice as costly as care for patients subdued with a TASER (n = 80); the K9 patients had significantly (one-tailed t tests) higher medical costs (P = 0.036), required more medical procedures (P = 0.014), and had longer LOS (P = 0.0046) than the TASER patients. Patients with K9 injuries had higher acuity and were significantly more expensive to treat with longer LOS than TASER injuries. LE agencies considering establishing and operating a K9 unit should initiate discussions with their local medical first responders and health-care facilities regarding the capabilities to treat severe K9 injuries to ensure adequate resource allocation.

Investigating Clinical and Cost Burdens of Law Enforcement-Related K9 Injuries: The Impact of "the Bite" on a Community Hospital

The decision to introduce canines (K9s) to a law enforcement (LE) agency does not typically involve the evaluation of the fiscal or clinical impact on local hospitals. This study compared injury, cost, and care associated with K9s to a common nonlethal force method, the Thomas A Swift Electrical Rifle (TASER), to highlight the cost and resources required to treat both patient types. Patients treated for LE-related K9 and TASER injuries at a Level I community-based trauma center (2011-2016) were evaluated for level of care required (e.g., surgeon/specialist), clinical interventions, proxy medical costs, and length of stay (LOS). Nearly one-third of K9 patients required tertiary-level medical care. The cost of treating the K9-inflicted injuries (n = 75) was almost twice as costly as care for patients subdued with a TASER (n = 80); the K9 patients had significantly (one-tailed t tests) higher medical costs (P = 0.036), required more medical procedures (P = 0.014), and had longer LOS (P = 0.0046) than the TASER patients. Patients with K9 injuries had higher acuity and were significantly more expensive to treat with longer LOS than TASER injuries. LE agencies considering establishing and operating a K9 unit should initiate discussions with their local medical first responders and health-care facilities regarding the capabilities to treat severe K9 injuries to ensure adequate resource allocation.

Pyeloduodenal Fistula in Xanthogranulomatous Pyelonephritis: A Series of Two Cases

Xanthogranulomatous inflammation, characterized by destruction and replacement of tissues with chronic inflammatory cells, including foamy histiocytes and hemosiderin-laden macrophages, is uncommon. In patients with xanthogranulomatous pyelonephritis, inflammation may extend from the kidney to the overlying duodenum, creating a pyeloduodenal fistula that further complicates medical and surgical management. We present two cases with recurrent kidney infections who each ultimately received a nephrectomy and repair of their duodenal fistula.

A unique case of popliteal artery transection after a motorcycle collision

Popliteal artery injuries may have devastating consequences if not recognized in a timely fashion. The risk of delayed diagnosis of a vascular injury is particularly high in blunt trauma to the lower extremity. We present a case of popliteal artery injury that is unusual in two respects: severity (a complete transection in the setting of a blunt injury) and lack of clinical and radiographic signs of the commonly associated musculoskeletal injuries.

The effects of glucose-lowering therapies on diabetic kidney disease

Chronic hyperglycemia and its associated metabolic products are key factors responsible for the development and progression of diabetic chronic kidney disease (CKD). Endocrinologists are tasked with detection and management of early CKD before patients need referral to a nephrologist for advanced CKD or dialysis evaluation. Primary care physicians are increasingly becoming aware of the importance of managing hyperglycemia to prevent or delay progression of CKD. Glycemic control is an integral part of preventing or slowing the advancement of CKD in patients with diabetes; however, not all glucose-lowering agents are suitable for this patient population. The availability of the latest information on treatment options may enable physicians to thwart advancement of serious renal complication in patients suffering from diabetes. This review presents clinical data that shed light on the risk/benefit profiles of three relatively new antidiabetes drug classes, the dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 analogs, and sodium glucose co-transporter 2 inhibitors, particularly for patients with diabetic CKD, and summarizes the effects of these therapies on renal outcomes and glycemic control for endocrinologists and primary care physicians. Current recommendations for screening and diagnosis of CKD in patients with diabetes are also discussed.

Importance of potassium in patients with acute myocardial infarction

The records of 151 patients entering a coronary care unit and subsequently diagnosed as having an acute myocardial infarction were reviewed. The prevalence of hypokalemia, its relationship to diuretic treatment and the development of either ventricular tachycardia or ventricular fibrillation were studied. At admission, 14% of patients were hypokalemic. The presence of hypokalemia was related to previous diuretic therapy. Twenty-three percent of patients receiving diuretics as compared to 7% of patients not taking diuretics had a serum potassium of 3.5 mEq/L or less. Thirty-seven patients experienced either ventricular tachycardia or ventricular fibrillation. The presence of hypokalemia was associated with an increased frequency of both of these arrhythmias. Sixty-seven percent of patients with a serum potassium of less than 3.1 mEq/L had these serious ventricular arrhythmias compared to 40% of patients with a serum potassium between 3.1 and 3.5 mEq/L and 20% of normokalemic patients. The prevalence of premature ventricular beats was not correlated with the presence of hypokalemia. We conclude that hypokalemia is not only a common problem in patients with acute myocardial infarction but a clinically significant factor in the development of life threatening arrhythmias. Primary prevention of hypokalemia and its prompt treatment are indicated in these patients.

Fluoxetine in depressed patients on dialysis

OBJECTIVE

To test the safety and efficacy of fluoxetine in patients with renal failure on dialysis.

METHOD

Fourteen patients with major depression and end stage renal disease on hemodialysis were randomized into two groups for an eight-week study. Subjects as well as investigators were blinded as to which subject received fluoxetine and which placebo. Patients were carefully monitored concerning adverse events, serum fluoxetine and norfluoxetine levels, and psychological measurements of degree of depression.

RESULTS

No patients discontinued treatment because of adverse events, all of which were minor. All psychological tests showed improvement in depression at the four-week and eight-weeks point, although statistical significance could only be demonstrated at the fourth week of this study. All patients in the active group had serum plasma concentrations of fluoxetine and norfluoxetine less than 250 ng/ml at eight weeks, similar to levels in patients with normal renal function in a previous open label study.

CONCLUSIONS

This study confirms the relative safety of fluoxetine in depressed patients in renal failure on hemodialysis. It also suggests that fluoxetine may be efficacious in depressed patients on dialysis.

Mode of activation of salt secretion by C-type natriuretic peptide in the shark rectal gland

We studied the modes of activation of the salt-secreting rectal gland of the spiny dogfish, Squalus acanthias, by the native cardiac peptide CNP. The stimulatory action of CNP in isolated perfused glands is inhibited by 10 mM procaine, presumably by blocking release of vasoactive intestinal peptide (VIP) from nerves. Procaine reduces the slope of the dose-response curve of human CNP and that of shark CNP (each P < 0.0001). CNP increases short-circuit current in cultured rectal gland cells from 4.8 +/- 1.6 to 27.0 +/- 7.8 microA/cm2. It also stimulates the secretion of chloride in isolated perfused glands in the presence of 10 mM procaine from 72 +/- 31 to 652 +/- 173 microeq. h(-1). g(-1). These results suggest that CNP has a direct cellular action not mediated by the neural release of VIP. The residual stimulation of perfused glands in the presence of procaine was almost completely inhibited by staurosporine [10 nM; an inhibitor of protein kinase C (PKC)] from 652 +/- 173 to 237 +/- 61 microeq. h(-1). g(-1). Although CNP stimulates guanylyl cyclase in shark rectal gland, chloride secretion of perfused glands was not elicited by 8-bromoadenosine-cGMP (8-BrcGMP) alone nor by the activator of PKC phorbol ester. The combination of PKC activation and 8-BrcGMP infusion, however, stimulated chloride secretion in perfused glands from 94 +/- 30 to 506 +/- 61 microeq. h(-1). g(-1), a level comparable to that observed in glands blocked with procaine. Several parallel pathways appear to be synergistic in activating chloride secretion stimulated by CNP in the rectal gland.

Prospective study of atrial natriuretic peptide for the prevention of radiocontrast-induced nephropathy

Radiocontrast-induced nephropathy (RCIN) is a common cause of hospital-acquired acute renal failure and is associated with a high mortality rate. RCIN is potentially preventable, because administration of the radiocontrast agent is predictable, and a high-risk population has been identified. This multicenter, prospective, randomized, double-blind, placebo-controlled trial was performed to evaluate the efficacy of intravenous atrial natriuretic peptide (anaritide, ANP 4-28) to prevent RCIN. Patients with stable chronic renal failure (serum creatinine greater than 1.8 mg/dL or serum creatinine between 1.5 and 1.8 mg/dL with estimated creatinine clearance of < or = 65 mL/min) were assigned to receive either placebo or one of three doses of anaritide (0.01 microg/kg/min, 0.05 microg/kg/min, or 0.1 microg/kg/min) for 30 minutes before and continuing for 30 minutes after radiocontrast administration. All patients were given intravenous 0.45% saline for 12 hours before the radiocontrast procedure and continuing for 12 hours after the last dose of radiocontrast. Both ionic and nonionic radiocontrast agents were administered. RCIN was defined as either an absolute increase of serum creatinine of > or = 0.5 mg/dL or a percent increase of > or = 25% over baseline. Of the 247 patients who completed the study, 50% had diabetes mellitus. There were no statistical differences in baseline serum creatinine, change in serum creatinine, or the incidence of RCIN. The incidence of RCIN was placebo, 19%; anaritide (0.01), 23%; anaritide (0.05), 23%; anaritide (0.1), 25%. Patients with diabetes mellitus had a significantly greater incidence of RCIN: placebo, 26% versus 9%; anaritide (0.01), 33% versus 13%; anaritide (0.05), 26% versus 21%; anaritide (0.1), 39% versus 8% (diabetic v nondiabetic, P < 0.002). There was no effect in the diabetic or nondiabetic groups by anaritide on the incidence of RCIN. Comparison of the highest-risk group of patients, defined as patients with diabetes mellitus and a baseline serum creatinine > or = 1.8 mg/dL, with the lowest-risk group, defined as patients without diabetes mellitus and a baseline serum creatinine of 1.8 mg/dL or less, did not show a beneficial effect of anaritide administration. In conclusion, administration of intravenous anaritide before and during a radiocontrast study did not reduce the incidence of RCIN in patients with preexisting chronic renal failure, with or without diabetes mellitus.

Transport mechanisms that mediate the secretion of chloride by the rectal gland of Squalus acanthias

The rectal gland of Squalus acanthias secretes chloride by a mechanism that has been termed "secondary active transport" because it depends on the activity of Na-K-ATPase. As currently described, chloride enters the cell across the basolateral cell membrane via the 2 chloride: sodium: potassium cotransporter. The energy for this electroneutral uphill movement of chloride and potassium is provided by the gradient for sodium directed into the cell. Present in the basolateral cell membrane is Na-K-ATPase that maintains the gradient for sodium. A potassium conductance, present as well in the basolateral cell membrane, recirculates the potassium. Chloride exits the cell across the luminal membrane via CFTR, the chloride conductance. This mechanism is widely distributed throughout vertebrates. This report reviews the experimental observations that led to the current definition of the mechanism of chloride transport in the rectal gland.

Role of guanylyl cyclase receptors for CNP in salt secretion by shark rectal gland

The role of C-type natriuretic peptide (CNP) and its guanylyl cyclase-linked receptors in mediating salt secretion by the rectal gland of the spiny dogfish shark (Squalus acanthias) was investigated using HS-142-1, a competitive inhibitor of the binding of natriuretic peptides to their guanylyl cyclase receptors. CNP binds to receptors and activates guanylyl cyclase in rectal gland membranes in a way that is inhibited by HS-142-1. Guanylyl cyclase activation in rectal gland membranes is far more sensitive to CNP than to atrial natriuretic peptide, whereas the reverse is true for membranes derived from mammalian (rabbit) renal collecting duct cells. HS-142-1 inhibited the stimulatory effect of CNP on ouabain-inhibitable oxygen consumption by rectal gland tubules. In explanted rectal glands continuously perfused with blood from intact donor sharks, HS-142-1 inhibited the increase in salt secretion normally provoked by infusing isotonic saline solutions into the donor animal. These results strongly support the view that CNP released into the systemic circulation in response to volume expansion mediates the secretion of chloride by the rectal gland via receptors linked to guanylyl cyclase.

The rectal gland of Squalus acanthias: a model for the transport of chloride

The rectal gland of the spiny dogfish shark, Squalus acanthias, secretes chloride by a furosemide sensitive process that has been termed "secondary active." Chloride enters the cell across the basolateral cell membrane via the sodium:potassium:2 chloride cotransporter. The energy for this electroneutral uptake step is provided by the electrochemical gradient for sodium directed into the cell. This is maintained by Na-K-ATPase present in the basolateral cell membrane. Present as well in the basolateral cell membrane is a potassium conductance that permits potassium to exit passively. Chloride leaves the cell across the luminal membrane via a chloride conductance closely similar to CFTR. The rectal gland is thus a model for the mechanism of secondary active chloride transport utilized by various epithelial organs throughout the vertebrate kingdom. This report reviews the humoral agents that regulate the secretion of chloride by the rectal gland and the intracellular mechanisms that mediate it. CNP, released from the heart in response to a volume stimulus, causes the release of VIP from nerves within the gland and together with VIP directly activates the rectal gland cell.

Fluoxetine in depressed patients with renal failure and in depressed patients with normal kidney function

Nine depressed patients with normal kidney function and seven depressed patients with renal failure undergoing hemodialysis were treated with open-label fluoxetine 20 mg/day in an 8-week study. The study was designed to evaluate the pharmacokinetics of fluoxetine during repeated administration and to acquire preliminary data regarding the effectiveness of this antidepressant in a population undergoing hemodialysis. Six patients in each group completed the study. Of these, five patients undergoing hemodialysis and five patients with normal renal function experienced moderate to marked improvement in their depression. Side effects were equal and minor in both groups, indicating that fluoxetine is safe in patients with renal impairment. The mean +/- standard deviation steady-state plasma concentrations of the sum of fluoxetine plus its metabolite norfluoxetine for patients completing 8 weeks (N = 6, both groups) were comparable for the patients undergoing hemodialysis (253 +/- 61 ng/ml) and those with normal kidney function (218 +/- 122 ng/ml; t = 1.5, df = 70, p > 0.13). These data suggest that the efficacy of fluoxetine in patients with renal failure undergoing hemodialysis is comparable to that in patients with normal kidney function. These data further suggest that renal failure and the process of hemodialysis do not materially alter the pharmacokinetics of fluoxetine or its major metabolite norfluoxetine.

Interviewing prepubertal children about suicidal ideation and behavior

OBJECTIVE

Much of the literature on assessment of suicidal children has focused on identifying risk factors associated with suicidal ideation and behavior in this population. Unique problems encountered in interviewing prepubertal children about suicidal ideation and behavior are examined in this paper.

METHOD

Observations of problems encountered in interviewing prepubertal children about suicidal ideation and behavior were gleaned in the context of interviews of children admitted to a child psychiatry inpatient unit and interviews of the parents of these children.

RESULTS

Unique problems include difficulties in assessment of suicidal intent, impact of cognitive development, particularly of the concept of death, interaction between current emotional state and memory of previous suicidal episodes, characteristics of play associated with suicidal states, effects of parents' attitudes toward assessment on information gathering, and the impact of certain risk factors on cognition and behavior during the interview.

CONCLUSION

Interviewing children about suicidal ideation and behavior necessitates that the clinician attend to multiple elements of the interview simultaneously. These interviews are further complicated by the stressful thoughts and feelings that can be raised in both clinician and child in reaction to exploring the child's suicidal ideation and behavior. Additional research is needed to refine the process of reliable interviewing of children about suicidal ideation and behavior and to develop instruments both to quantitate the different elements of these interviews and to guide the clinicians conducting them.

Legal considerations of medical-practice employee selection

This article reviews the legal requirements that physicians face as employers, including Title VII of the Civil Rights Act of 1964, the Americans With Disabilities Act of 1990, and the Age Discrimination in Employment Act of 1967, as well as the preservation of at-will rights. It also describes the various employment methods that medical practices can use, including structured interviews, tests, work samples, simulations, references, drug tests, and application forms. Finally, the physician's role as supervisor of the employment process is discussed.

The effect of mercury on chloride secretion in the shark (Squalus acanthias) rectal gland

1. Mercuric chloride inhibited chloride secretion in a dose dependent way in isolated perfused rectal glands. The effect was readily apparent at a concentration of 10(-6) M and profound and irreversible at 10(-4) M. 2. The dithiol dithiothreitol (DTT) 10(-2) M completely prevented the effect of 10(-6) M mercuric chloride, reduced that at 10(-5) M and 10(-4) M, and made the inhibition at the latter concentration reversible. 3. Two organic mercurials, mersalyl and meralluride, that are effective diuretics in the mammalian kidney, and p-chloromercuribenzoyl sulfonic acid (PCMBS), that has no diuretic activity, had no effect on chloride secretion by the rectal gland. 4. The effect of mersalyl was not modified by lowering the pH of the solution perfusing the glands. 5. These results indicate that inorganic mercury and organic mercurials do not share the same mechanism of action. 6. The absence of an effect of organic mercurials on chloride transport in the rectal gland suggests that its effect on another chloride transporting epithelia, the thick ascending limb of the loop of Henle, is not mediated by inhibition of the chloride cotransporter or Na+, K(+)-ATPase, common to both epithelia.

Development of a radioimmunoassay to bradykinin using monoclonal antibodies

We report here our success in the preparation of monoclonal antibody directed against bradykinin. We further demonstrate that the preparation is easier and less time-consuming compared to the preparation of polyclonal antibodies. The polyclonal antibody provides a ready source of the reagent very much required in the performance of the kinin radioimmunoassay. Limitation of this reagent was in the fact that it did not attain the desired specificity to distinguish between the kinin peptides. Nevertheless, it is interesting to note that the domains of recognition sites can be very similar for monoclonal or polyclonal response, particularly when the antigen is smaller (molecular size of about 1 Kd) as is the case with bradykinin. Our laboratory produced the first monoclonal antibodies at Brown University. These antibodies were directed to bradykinin in BALB-C mice and could recognize bradykinin, lysyl-bradykinin and met-lysyl-bradykinin. Using this reagent it is possible to develop and validate an RIA which can be utilized to measure total kinins in tissues and body fluids. Although this antibody shows similar specificity as found with the polyclonal antibody, the ease and shorter duration of this preparation may make it a reagent of choice.

Using a patient survey for marketing a professional health care practice

Small, private, professional health care practices are at a disadvantage when conducting market survey research because they cannot afford to employ or purchase the expensive specialized marketing skills of their larger competitors. The author describes a method that small private practices can use to conduct patient marketing surveys. Survey findings are reported and examples are provided of how the results influenced subsequent marketing decisions. Suggestions are offered to help ensure the success of similar studies in other practices.

Physician assistants as administrators. Opportunities in management. Panel discussion

Physician assistants' involvement in administration focused on educational programs early in the profession's history. Recently, PAs have begun to work as administrators in hospitals and other settings. Preparation for management positions varies from on-the-job training to graduate degrees in business administration and public health. Clinical experience as a PA increases marketability in health care administration. Physician assistants who work as clinicians and administrators may find it difficult to balance responsibilities. In this forum, four PAs who helped pioneer this role explain how they became administrators and answer questions raised by other PAs interested in this growing job opportunity.

Comparative effects of pinacidil and prazosin on blood pressure, weight, plasma volume, the renin-angiotensin-aldosterone system, and the renal kallikrein-kinin system in patients with essential hypertension

Patients with essential hypertension were randomized to treatment with either prazosin or pinacidil, a new direct-acting vasodilator. Factors that might modulate the antihypertensive response and result in pseudotolerance to these drugs were measured before initiation of therapy and following 12 weeks of treatment. Despite significant reductions in blood pressure, pinacidil and prazosin did not produce an increase in plasma volume, did not activate the renin-angiotensin-aldosterone system, and did not interfere with the renal kallikrein-kinin system. The data fail to reveal evidence of physiologic compensatory changes that would lead to the development of pseudotolerance.

Effects of changing salt and water balance on renal kallikrein, kininogen and kinin

The kallikrein-kininogen-kinin system (KKK) has been implicated in the renal sodium excretion response to changes in dietary sodium. However, both increases and decreases in the activity of this system have been observed when urinary sodium excretion is augmented by a variety of maneuvers. To further evaluate the potential physiologic role of this system, we measured three components of the KKK system in urine. Total kallikrein, intact kininogen, and kinin were measured twice in normal individuals during balance on both a high (250 mEq/day) or low (10 mEq/day) sodium intake. A consistent and significant reduction in the activity of all three components of the KKK system was noted during the high salt intake. Furthermore, during the high sodium intake, further acute reductions in components of this system were observed when an acute saline but not water load was administered. The consistent response of the various components of the KKK system to both acute and chronic sodium loading suggests that the system is physiologically linked to the regulation of sodium balance. However, the directional changes argue against a primary natriuretic effect of this system.

Atrial natriuretic peptide stimulates salt secretion by shark rectal gland by releasing VIP

Salt secretion by the isolated perfused rectal gland of the spiny dogfish shark, Squalus acanthias, is stimulated by synthetic rat atrial natriuretic peptide (ANP II) as well as extracts of shark heart, but not by 8-bromo-cyclic guanosine 5'-monophosphate. Cardiac peptides have no effect on isolated rectal gland cells or perfused tubules, suggesting that stimulation requires an intact gland. The stimulation of secretion by ANP II is eliminated by maneuvers that block neurotransmitter release. These include: perfusion with procaine (10(-2) M), perfusion with high Mg2+ (9.5 mM) and low Ca2+ (0.5 mM) concentrations, and addition to the perfusate of the calcium channel blockers nifedipine (10(-6)M), diltiazem (5 X 10(-5)M), or verapamil (10(-4)M). Cardiac peptides stimulate the release of vasoactive intestinal peptide (VIP), known to be present in rectal gland nerves, into the venous effluent or perfused glands in parallel with their stimulation of salt secretion, but the release of VIP induced by ANP II is prevented by perfusion with procaine. Cardiac peptides thus appear to regulate rectal gland secretion by releasing VIP from neural stores within the gland. It is possible that other physiological effects of these hormones might be explained by an action to enhance local release of neurotransmitters.

Urinary kininogen: a possible regulator of kinin formation in normal individuals and subjects with essential hypertension, end-stage renal and liver disease

Most previous studies have not significantly correlated urinary kallikrein to urinary kinins. We investigated whether urinary kininogen might influence kinin formation within the urine. On an ad-lib diet the 24 hour excretion of total and intact kininogen, kinins and kallikrein was determined in 24 control subjects, 20 untreated essential hypertensives, 12 with end-stage renal disease and 8 subjects with liver disease. Kallikrein and kinins were measured by a direct radioimmunoassay. Total kininogen was determined from the sum of preformed kinins and kinins generated after trypsin (intact kininogen). Cross reactivity between purified human low molecular weight kininogen and bradykinin antiserum was 3%. Total and intact kininogen were significantly correlated with kinins in controls, essential hypertension and liver disease. In essential hypertension, end-stage renal and liver diseases kinins were significantly decreased. This was associated with a reduction in kininogen but not kallikrein in essential hypertension and liver disease, and a reduction in kallikrein but not kininogen in end-stage renal disease. Thus, renal kinin generation in various states may be affected by either or both kininogen and kallikrein.

Thiazide induced hypotension: the role of plasma volume reduction and the urinary kallikrein system

The hypotensive response the thiazide diuretics was studied in 15 males with moderate essential hypertension and correlated with serial changes in plasma volume, weight, plasma renin activity, urinary aldosterone, and urinary kallikrein, both total and activity. A greater than 10 mmHg fall in mean arterial pressure after four weeks of treatment defined the responders to therapy (n = 10) while all others were considered non-responders (n = 5). In responders, the fall in mean arterial pressure was accompanied by sustained reduction in plasma volume and weight. No sustained fall in plasma volume was noted in non-responders. Plasma renin activity and urinary aldosterone excretion increased in responders but not in non-responders. Urinary kallikrein, both total and active, increased in the responders but remained unchanged in the non-responders. The results are consistent with the hypothesis that a sustained reduction in plasma volume is necessary for the maintenance of a hypotensive response to thiazides. Stimulation of the renal kallikrein-kinin system may be necessary to balance the antinatriuretic and pressor effects of the renin-angiotensin-aldosterone system. If unopposed, this system would return plasma volume and blood pressure to pretreatment levels.

Ventricular arrhythmias in patients with myocardial infarction and ischaemia. The role of serum potassium

An association between low serum potassium concentrations and ventricular arrhythmias has been observed by a number of investigators in patients with both acute myocardial infarction and symptomatic angina. The increased frequency of ventricular fibrillation in patients with low serum potassium concentrations has not been attributable to differences in the size or location of the infarct or concomitant digitalis administration. Although prior diuretic usage is frequently associated with a low serum potassium concentration, diuretic usage in the absence of significant changes in serum electrolytes is not associated with an increase in malignant ventricular arrhythmias. It is not clear whether the alterations in serum potassium are important in the pathogenesis of the arrhythmias or merely a marker for other arrhythmogenic factors. To the extent that changes in serum potassium contribute to the production of serious ventricular arrhythmias, efforts should be directed at the correction of such electrolyte disturbances. Attempts to increase the serum potassium in acute cases do not appear to be successful in preventing ventricular arrhythmias in this setting. Primary prevention of electrolyte disturbances would seem to offer more effective protection against serious arrhythmias. Long term studies with beta-blockers support this premise.

The role of urinary kininogen in the regulation of kinin generation

The kallikrein-kininogen-kinin system has been postulated to play a role in the regulation of blood pressure and modulation of renal salt and water transport. The activity of this system has usually been determined by measurements of urinary kallikrein excretion. However, urinary kallikrein rarely correlates with simultaneously measured urinary kinins. To further evaluate the factors influencing urinary kinin excretion, we evaluated the role of urinary kininogen in this system. Urines were analyzed from normal subjects and individuals with untreated essential hypertension and end-stage renal disease. Intact urinary kininogen was significantly correlated with urinary kinins in normal subjects (r = 0.65, P = 0.003) and essential hypertensives (r = 0.52, P = 0.026). In both essential hypertension and end-stage renal disease, urinary kinins were significantly decreased (8.00 +/- 1.93, 0.90 +/- 0.18, P less than 0.05, respectively) compared to controls (23.73 +/- 5.20). In essential hypertensives, the reduction in urinary kinins was paralleled by a reduction in intact kininogen with a normal excretion of kallikrein. In end-stage renal disease, the reduction in kinins was paralleled by a reduction in kallikrein with a normal excretion of intact kininogen. This data suggests that kininogen may be an important determinant of urinary kinin excretion in various disease states.

Ventricular arrhythmias in patients with myocardial infarction and ischaemia. Relationship to serum potassium and magnesium

Alterations in serum electrolytes may frequently accompany ischaemic heart disease. Many of these patients are hypertensive and receive diuretic therapy which results in chronic lowering of serum potassium and magnesium. In addition, acute catecholamine-induced shifts of potassium into cells may also occur in the setting of acute myocardial ischaemia. An association between low serum potassium concentrations and ventricular arrhythmias has been observed by a number of investigators in patients with acute myocardial infarction. The increased frequency of ventricular fibrillation with low serum potassium concentrations is particularly relevant as this arrhythmia is associated with poor prognosis, even in the setting of a coronary care unit. Ventricular fibrillation also occurs with increased frequency in patients with angina who have low serum potassium levels. The possibility that low serum potassium concentrations may be a risk factor in the increased incidence of sudden death in such patients should be considered. Diuretic-induced magnesium deficiency may be yet another factor favouring the emergence of ventricular arrhythmias in patients with ischaemic heart disease. While such electrolyte disturbances do not account for all of the ventricular irritability seen in patients with ischaemic heart disease, they represent easily identifiable and treatable risk factors. Primary prevention of these electrolyte disturbances in patients at risk for coronary ischaemia is recommended.

Elevated nicotine levels in patients undergoing hemodialysis. A role in cardiovascular mortality and morbidity?

The incidence of cardiovascular disease in patients with end-stage renal disease undergoing long-term maintenance hemodialysis is excessively high. The reason for this excess morbidity and mortality has remained unclear. Cigarette smoking is one factor that has been associated with increased cardiovascular risk. To learn more about the effects of tobacco smoking in these patients, nicotine levels were assayed in the serum of 10 patients with end-stage renal disease undergoing maintenance hemodialysis. Specimens were obtained before and after smoking one cigarette and following dialysis or an equivalent period in control subjects. Serum nicotine levels (+/-SEM) in control subjects measured 19.0 +/- 7.2 ng/ml initially, 36.1 +/- 8.2 ng/ml after smoking, and 9.3 +/- 3.5 ng/ml after a period of 4.35 hours. These compare with respective values of 76.6 +/- 16.8 ng/ml (p less than 0.004), 132.9 +/- 19.7 ng/ml (p less than 0.001), and 51.9 +/- 10.5 ng/ml (p less than 0.001) in patients undergoing hemodialysis. These data demonstrate markedly higher nicotine levels in hemodialysis patients compared with control subjects, which may have serious implications regarding morbidity and mortality.

In vivo effect of volume expansion on rectal gland function. II. Hemodynamic changes

Intravascular volume expansion causes a 300% increase in the rate of fluid secretion from, and blood flow to, the in vivo rectal gland of the spiny dogfish Squalus acanthias. Similar increases are also observed in explanted rectal glands perfused through a catheter from the dorsal aorta of a volume-expanded dogfish. Stimulation of rectal gland secretion by volume expansion is not associated with a change in the ratio of chloride secreted to oxygen consumed by the rectal gland and the oxygen extraction ratio, suggesting that an increase in blood flow is necessary to support the increased rate of chloride secretion. Perfusion of the explanted gland with bumetanide (10(-4) M) completely inhibits the secretory response to volume expansion but does not prevent the increase in blood flow. Bumetanide also inhibits dibutyryl adenosine 3',5'-cyclic monophosphate- and theophylline-induced increases in chloride secretion but does not inhibit the hyperemic response. Somatostatin inhibits the secretory response of the explanted gland to volume expansion but does not prevent the increase in blood flow. Although an increase in blood flow is necessary to support the increased energy requirement of enhanced transport, the secretory response and the increase in blood flow appear to be independently regulated and mediated, at least in part, by humoral factors.

Thallium-201 myocardial imaging in patients on chronic hemodialysis

10 long-term hemodialysis patients had immediate and redistribution thallium-201 myocardial imaging performed after a course of hemodialysis. Subjects had EKGs done on the same day before and after dialysis. 3 of the 10 subjects had resting thallium-201 myocardial imaging obtained on non-dialysis days. 60% of the electrocardiograms showed changes with dialysis. All 13 thallium studies were abnormal, showing multiple transient filling defects at rest. Most subjects had permanent filling defects as well. It is concluded that hemodialysis patients have a high frequency of abnormal thallium-201 myocardial images at rest. The cause of these abnormal studies is uncertain.

Cimetidine-induced interstitial nephritis with response to prednisone therapy

Acute renal failure developed in a patient after she received cimetidine therapy. A renal biopsy specimen showed acute interstitial nephritis. Withdrawal of cimetidine therapy led to improvement of renal function. Rechallenge with cimetidine occurred during prednisone therapy. Renal function continued to improve, but worsened when the treatment with these steroids was discontinued.

Phantom urinary symptoms in hemodialysis patients

Phantom urinary symptoms were reported by 12 or 24 hemodialysis patients surveyed. The symptoms were present in all age groups. The absence of any correlation between the occurrence of these symptoms and length of time and dialysis suggest that urinary phantoms in hemodialysis patients may persist over time in contrast to the gradual disappearance of phantoms symptoms resulting from amputation. No correlation was found between occurrence of phantom symptoms and sexual impairment, actual voiding of urine or symptoms of peripheral neuropathy.

Ketone body effects on glutamine metabolism in isolated kidneys and mitochondria

beta-Hydroxybutyrate (but not acetoacetate) caused marked inhibition of ammonia production and glutamine extraction in isolated perfused kidneys from normal rats. Glutamine synthesis was not affected by beta-hydroxybutyrate (BHB). Measurement of metabolite levels in freeze-clamped kidneys showed that BHB increased glutamine concentration, decreased ammonia concentration, and reduced the mitochondrial NAD+/NADH ratio (calculated) in perfused kidneys. BHB inhibited flux through the glutamate dehydrogenase pathway, probably as a result of reduction in the NAD+/NADH ratio, in isolated renal mitochondria. In isolated perfused kidneys from acidotic rats, ammonia production and mitochondrial NAD+/NADH were both elevated and BHB did not inhibit renal ammoniagenesis. Although ammonia production in the acidotic kidneys was not directly related to the mitochondrial NAD+/NADH ratio, the elevation of this ratio may have permitted a normal rate of oxidation of glutamine end products--which is essential for maintaining the elevated ammoniagenesis--to take place in the presence of BHB.

The significance of beta-2 microglobulinuria associated with gentamicin therapy

Gentamicin is a nephrotoxic agent known to damage the proximal tubule,--a site of low molecular weight (LMW) protein reabsorption and catabolism. The effect of gentamicin was investigated on three LMW proteins--amylase, light chains, and beta 2 microglobulin--and the effects were correlated on the latter to renal function as determined by creatinine clearance (GFR). The renal excretion of beta 2 microglobulin (beta 2M) was studied in 18 patients receiving gentamicin and eight control patients. Both gentamicin and control patients had similar mean ages and serum beta 2M. Twelve of the 18 gentamicin treated patients had marked increases in beta 2M excretion. The mean daily 2 beta microglobulin excretion for the gentamicin treated group was 10,511 microgram while that of the control group was 102 microgram. Serial determinations in 10 of the gentamicin treated patients revealed an increase in beta 2M excretion within 48 hours of starting therapy. No deterioration of GFR was seen in any patient. In four patients, beta 2M excretion decreased while still receiving gentamicin. The renal handling of amylase was found to be normal in four patients and mildly abnormal in three patients receiving gentamicin who also had increased beta 2M excretion. Urinary light chains were determined in four of these seven patients and found to be normal. It is concluded that gentamicin induces an early and often transient tubular proteinuria. This tubular proteinuria is not associated with clinical nephrotoxicity.

Electrocardiographic changes following dialysis

We investigated electrocardiographic changes occurring after hemodialysis in 20 male patients with chronic renal failure. Changes in the configuration of T wave, ST segment and R wave consistent with ischemia were found in 30, 45, and 75%, respectively. Contrary to prior speculation the R wave height did not vary with the volume changes of body fluid occurring in dialysis. It is concluded that ischemic-appearing changes of uncertain significance are common in the postdialysis population.

Disseminated Mycobacterium chelonei infection: response to sulfonamides

A disseminated infection due to Mycobacterium chelonei occurred in a hemodialysis patient after rejection of his second renal transplant. Painful subcutaneous nodules and abscesses were found on both legs. Therapy with sulfisoxaxole and kanamycin produced a prompt response twice, as did sulfisoxazole alone on 2 additional occasions, despite resistance in vitro to both drugs. Clinical relapses occurred 3 times when administration of sulfisoxazole was discontinued.

Bartter's syndrome. New insights into pathogenesis and treatment

Discussed here is a patient with normotension, hypokalemic alkalosis, hyperreninemia, hyperaldosteronism, juxtaglomerular cell hyperplasia and insensitivity to the pressor effects of angiotensin (Bartter's syndrome). The hyperreninemia and hyperaldosteronism were both suppressible with volume expansion. Hypokalemia was correctible both short-term with potassium chloride infusions and long-term with spironolactone. Nevertheless, the abnormal pressor response to infused angiotensin could not be corrected by these maeuvers, suggesting that this defect is likely to be of primary pathophysiologic significance. We found that potassium loading markedly stimulated aldosterone excretion. This may explain the inadequacy of potassium supplementation alone to correct the hypokalemia and the observed "escape" from the potassium conserving effects of spironolactone seen in patients with Bartter's syndrome. The administration of propranolol in large doses only partially suppressed the marked hyperreniemia of our patient and failed to prevent a subsequent rise in the renin level which was associated with spironolactone therapy. In contrast, suppression of the renin level to normal was demonstrated by sodium loading. It is suggested that patients with Bartter's syndrome be treated simultaneously with large doses of spironolactone and a high sodium intake.

Thiocyanate inhibition of ATPase and its relationship to anion transport

Adenosine triphosphatase activity not dependent on sodium or potassium but inhibited by thiocyanate is present in broken-cell homogenates of eel gill and rat kidney. This enzymatic property is predominantly associated with mitochondria, although thiocyanate-inhibited ATPase can also be detected in microsomes with little or no mitochondrial contamination as measured by the activity of the mitochondrial marker enzyme succinic dehydrogenase. When eels are transferred from fresh to salf water, thus increasing active outward transport of chloride across the gill, the thiocyanate-inhibited ATPase of gill microsomes does not change, though the activities of succinic dehydrogenase and Na-K-ATPase in gill homogenates are augmented. The thiocyanate-inhibited ATPase of homogenates of outer renal medulla does not differ from that of renal cortex, in contrast to Na-k-atpase which is higher in renal medulla than in cortex. The data do not support a role for thiocyanate-inhibited ATPase in active chloride transport by epithelial tissues.