Validation of a new in vitro Sun Protection Factor method to include a wide range of sunscreen product emulsion types

In 2017, Cosmetics Europe performed a double‐blinded ring test of 24 emulsion‐type sunscreen products, across 3 in vivo test laboratories and 3 in vitro test laboratories, using a new candidate in vitro SPF test method. Based on the results of this work, an article was published showing how data derived from a new lead candidate method conform to new International Standards (ISO) acceptance criteria for alternative SPF test methods (Any alternative method should consider the matrix effect and if required, specify the matrix applicability of the method; Criterion 1a: Systematic differences between methods should be negligible: 95% of all individual results of an alternative method are within the range of ±2× reproducibility standard deviation of the in vivo method, that is overall bias must be below 0.5× reproducibility standard deviation of the in vivo method; Criterion 1b: Measurement uncertainty of an alternative method should be below the measurement uncertainty of the in vivo method. Candidate method predicted values must fall within the full ‘funnel’ (SPF 6‐50+) limits proposed by Cosmetics Europe (derived from the same minimum test design, that is using the ISO24444 Method to measure at least 24 products across at least 3 laboratories using at least 5 test subjects/laboratory, in a blinded fashion).). Of the 24 sunscreen products tested, the majority of emulsions were of the oil‐in‐water (O/W) type, whereas only one was water‐in‐oil (W/O) and there were no products with a mineral‐only sun filter system. In order to confirm the scope of this method, therefore, a new study was conducted that included 73 W/O (12 mineral + organic, 44 mineral only and 17 organic only) and 3 O/W mineral‐only, emulsion‐type sunscreen products (a total of 76 new sunscreen products). When combined with the previous 24 products (tested in 3 different laboratories), this yielded a new data set comprising a total of 100 emulsion‐type sunscreen products, with SPF values ranging from 6 to 50+ (with a total of 148 data points). These products were tested using the double‐plate in vitro SPF test method and compared with the ISO TC217/WG7 acceptance criteria for alternative SPF test methods. Over 95% of paired in vitro: in vivo SPF values lay within the upper and lower limits of the ISO acceptance criteria funnel, with no bias. This new in vitro SPF test method, therefore, meets the minimum requirements for an alternative SPF test method to ISO24444:2010, for emulsion‐type sunscreen products (which make up the majority of marketed sunscreen products).

Extent of Microstructural Tissue Damage Correlates with Hemodynamic Failure in High-Grade Carotid Occlusive Disease: An MRI Study Using Quantitative T2 and DSC Perfusion

BACKGROUND AND PURPOSE

Chronic hemodynamic impairment in high-grade carotid occlusive disease is thought to cause microstructural abnormalities that might be subclinical or lead to subtle symptoms including cognitive impairment. Quantitative MR imaging allows assessing pathologic structural changes beyond macroscopically visible tissue damage. In this study, high-resolution quantitative T2 mapping combined with DSC-based PWI was used to investigate quantitative T2 changes as a potential marker of microstructural damage in relation to hemodynamic impairment in patients with unilateral high-grade carotid occlusive disease.

MATERIALS AND METHODS

Eighteen patients with unilateral high-grade ICA or MCA stenosis/occlusion were included in the study. T2 values and deconvolved perfusion parameters, including relative CBF, relative CBV, and the relative CBF/relative CBV ratio as a potential indicator of local cerebral perfusion pressure, were determined within areas with delayed TTP and compared with values from contralateral unaffected areas after segmentation of normal-appearing hypoperfused WM and cortical regions. Hemispheric asymmetry indices were calculated for all parameters.

RESULTS

Quantitative T2 was significantly prolonged (P < .01) in hypoperfused tissue and correlated significantly (P < .01) with TTP delay and relative CBF/relative CBV reduction in WM. Significant correlations (P < .001) between TTP delay and the relative CBF/relative CBV ratio were found both in WM and in cortical areas.

CONCLUSIONS

Quantitative T2 can be used as a marker of microstructural tissue damage even in normal-appearing GM and WM within a vascular territory affected by high-grade carotid occlusive disease. Furthermore, the extent of damage correlates with the degree of hemodynamic failure measured by DSC perfusion parameters.

Restoration of Kv7 Channel-Mediated Inhibition Reduces Cued-Reinstatement of Cocaine Seeking

Cocaine addicts display increased sensitivity to drug-associated cues, due in part to changes in the prelimbic prefrontal cortex (PL-PFC). The cellular mechanisms underlying cue-induced reinstatement of cocaine seeking remain unknown. Reinforcement learning for addictive drugs may produce persistent maladaptations in intrinsic excitability within sparse subsets of PFC pyramidal neurons. Using a model of relapse in male rats, we sampled >600 neurons to examine spike frequency adaptation (SFA) and afterhyperpolarizations (AHPs), two systems that attenuate low-frequency inputs to regulate neuronal synchronization. We observed that training to self-administer cocaine or nondrug (sucrose) reinforcers decreased SFA and AHPs in a subpopulation of PL-PFC neurons. Only with cocaine did the resulting hyperexcitability persist through extinction training and increase during reinstatement. In neurons with intact SFA, dopamine enhanced excitability by inhibiting Kv7 potassium channels that mediate SFA. However, dopamine effects were occluded in neurons from cocaine-experienced rats, where SFA and AHPs were reduced. Pharmacological stabilization of Kv7 channels with retigabine restored SFA and Kv7 channel function in neuroadapted cells. When microinjected bilaterally into the PL-PFC 10 min before reinstatement testing, retigabine reduced cue-induced reinstatement of cocaine seeking. Last, using cFos-GFP transgenic rats, we found that the loss of SFA correlated with the expression of cFos-GFP following both extinction and re-exposure to drug-associated cues. Together, these data suggest that cocaine self-administration desensitizes inhibitory Kv7 channels in a subpopulation of PL-PFC neurons. This subpopulation of neurons may represent a persistent neural ensemble responsible for driving drug seeking in response to cues.SIGNIFICANCE STATEMENT Long after the cessation of drug use, cues associated with cocaine still elicit drug-seeking behavior, in part by activation of the prelimbic prefrontal cortex (PL-PFC). The underlying cellular mechanisms governing these activated neurons remain unclear. Using a rat model of relapse to cocaine seeking, we identified a population of PL-PFC neurons that become hyperexcitable following chronic cocaine self-administration. These neurons show persistent loss of spike frequency adaptation, reduced afterhyperpolarizations, decreased sensitivity to dopamine, and reduced Kv7 channel-mediated inhibition. Stabilization of Kv7 channel function with retigabine normalized neuronal excitability, restored Kv7 channel currents, and reduced drug-seeking behavior when administered into the PL-PFC before reinstatement. These data highlight a persistent adaptation in a subset of PL-PFC neurons that may contribute to relapse vulnerability.

Validation of an in vitro sun protection factor (SPF) method in blinded ring-testing

OBJECTIVE

The objective of this work was to investigate the utility of a new in vitro SPF test method in blinded ring-testing, against new ISO acceptance criteria.

METHODS

Twenty four blinded, commercial, emulsion-type, primary sunscreen products, covering the full range of labelled SPF in Europe (SPF6 - 50+), were tested by three test institutes using the current ISO24444:2010 In Vivo SPF Test Method and simultaneously by three separate test laboratories using a new candidate in vitro SPF test method, developed under the leadership of Cosmetics Europe (CE). The resulting relationship between in vitro SPF and in vivo SPF values was then compared with acceptance criteria developed recently by the International Standards (ISO) TC217/WG7 Sun Protection Test Methods Working Group.

RESULTS

Analysis of the mean inter-laboratory in vitro and mean inter-institute in vivo SPF values revealed a strong correlation between in vitro and in vivo values, with a Pearson correlation coefficient of r2  = 0.88 (P < 0.0001), a slope of 1.01 and a non-significant intercept (-1.48; P = 0.62). When these data were compared to the new ISO WG7 acceptance criteria, method bias was found to be extremely low and over 95% of the coupled data lay within the model 'funnel' (defined by upper and lower confidence intervals).

CONCLUSION

In conclusion, the results of blinded ring testing and comparison to new ISO WG7 acceptance criteria indicate that a new in vitro SPF test method meets (and exceeds) these minimum criteria and is an interesting candidate for possible deployment as an industry test methodology.

Probing the Single-Particle Character of Rotational States in ^{19}F Using a Short-Lived Isomeric Beam

A beam containing a substantial component of both the J^{π}=5^{+}, T_{1/2}=162  ns isomeric state of ^{18}F and its 1^{+}, 109.77-min ground state is utilized to study members of the ground-state rotational band in ^{19}F through the neutron transfer reaction (d,p) in inverse kinematics. The resulting spectroscopic strengths confirm the single-particle nature of the 13/2^{+} band-terminating state. The agreement between shell-model calculations using an interaction constructed within the sd shell, and our experimental results reinforces the idea of a single-particle-collective duality in the descriptions of the structure of atomic nuclei.

An Assessment of Participant-Described Interprofessional Oral Health Referral Systems Across Rurality

PURPOSE

As a means to identify and quantify oral health interprofessional collaborative practice (IPP), we examined participant-described medical-to-dental (M2D) referral networks and how they function across rurality.

METHODS

We conducted a cross-sectional survey on the appraisal of IPP referral systems in 2016. Secondarily, we examined if rural health clinics (RHCs) have different experiences with M2D referrals compared to other practice types. Independent variables included geographic and organizational indicators, referral system attributes, and respondent characteristics. Data were coded by Census region and state Medicaid expansion status. Bivariable and multivariable analyses were conducted using SAS.

FINDINGS

A convenience cohort (n = 559) from 44 states was examined. Nearly, half (48.7%) reported dependable M2D referral systems. In bivariate analysis, all independent variables were significant except for state Medicaid expansion status. In multivariable analysis, Census region retained significance (P = .0093). Organization type and practice issues with no shows/missed appointments continued to have significance (P < .001 and .002, respectively). Accountable care organizations were over 5 times (5.72, P = .001) more likely than RHCs to report dependable M2D referral systems. Federally qualified health clinics were slightly over 3 times more likely than RHCs to report dependable M2D referral (3.04, P < .001). No differences between RHCs and other private practices were observed.

CONCLUSIONS

The importance of IPP continues to be promoted in the current health care environment. Our study demonstrates that, in this motivated study population, M2D referrals can work well, even in rural areas. Organization type, directionality of referral, broken appointment rates, and electronic health information management were all found to significantly impact the respondents' rating on the dependability of an M2D referral process.

Sensitivity of diffusion MRI to perilesional reactive astrogliosis in focal ischemia

Reactive astrogliosis is a response to injury in the central nervous system that plays an essential role in inflammation and tissue repair. It is characterized by hypertrophy of astrocytes, alterations in astrocyte gene expression and astrocyte proliferation. Reactive astrogliosis occurs in multiple neuropathologies, including stroke, traumatic brain injury and Alzheimer's disease, and it has been proposed as a possible source of the changes in diffusion magnetic resonance imaging (dMRI) metrics observed with these diseases. In this study, the sensitivity of dMRI to reactive astrogliosis was tested in an animal model of focal acute and subacute ischemia induced by the vasoconstricting peptide, endothelin-1. Reactive astrogliosis in perilesional cortex was quantified by calculating the astrocyte surface density as determined with a glial fibrillary acidic protein (GFAP) antibody, whereas perilesional diffusion changes were measured in vivo with diffusional kurtosis imaging. We found substantial changes in the surface density of GFAP-positive astrocyte processes and modest changes in dMRI metrics in the perilesional motor cortex following stroke. Although there are time point-specific correlations between dMRI and histological measures, there is no definitive evidence for a causal relationship.

Evaluation of the accuracy of 7 digital scanners: An in vitro analysis based on 3-dimensional comparisons

STATEMENT OF PROBLEM

As digital impressions become more common and more digital impression systems are released onto the market, it is essential to systematically and objectively evaluate their accuracy.

PURPOSE

The purpose of this in vitro study was to evaluate and compare the trueness and precision of 6 intraoral scanners and 1 laboratory scanner in both sextant and complete-arch scenarios. Furthermore, time of scanning was evaluated and correlated with trueness and precision.

MATERIAL AND METHODS

A custom complete-arch model was fabricated with a refractive index similar to that of tooth structure. Seven digital impression systems were used to scan the custom model for both posterior sextant and complete arch scenarios. Analysis was performed using 3-dimensional metrology software to measure discrepancies between the master model and experimental casts.

RESULTS

Of the intraoral scanners, the Planscan was found to have the best trueness and precision while the 3Shape Trios was found to have the poorest for sextant scanning (P<.001). The order of trueness for complete arch scanning was as follows: 3Shape D800 >iTero >3Shape TRIOS 3 >Carestream 3500 >Planscan >CEREC Omnicam >CEREC Bluecam. The order of precision for complete-arch scanning was as follows: CS3500 >iTero >3Shape D800 >3Shape TRIOS 3 >CEREC Omnicam >Planscan >CEREC Bluecam. For the secondary outcome evaluating the effect time has on trueness and precision, the complete- arch scan time was highly correlated with both trueness (r=0.771) and precision (r=0.771).

CONCLUSIONS

For sextant scanning, the Planscan was found to be the most precise and true scanner. For complete-arch scanning, the 3Shape Trios was found to have the best balance of speed and accuracy.

[Traumatic hip dislocation in a 6-year-old male child: Seldom but demanding]

Traumatic hip dislocations in children are not frequent but constitute true emergencies. They require urgent reduction because of the risk of consecutive avascular necrosis of the femoral head. We report a 6-year-old boy with traumatic posterior hip dislocation on a vacation abroad. After closed reduction the day of the accident, a hip spica cast was applied and the patient was transferred home. Once home, X‑ray and CT diagnostics were completed by MRI. In future, long-term clinical and radiological investigations for avascular necrosis and growth disorders, as well as thoroughly informing the parents, should be mandatory.

Three-dimensional imaging of carbonyl sulfide and ethyl iodide photodissociation using the pixel imaging mass spectrometry camera

The Pixel Imaging Mass Spectrometry (PImMS) camera is used in proof-of-principle three-dimensional imaging experiments on the photodissociation of carbonyl sulfide and ethyl iodide at wavelengths around 230 nm and 245 nm, respectively. Coupling the PImMS camera with DC-sliced velocity-map imaging allows the complete three-dimensional Newton sphere of photofragment ions to be recorded on each laser pump-probe cycle with a timing precision of 12.5 ns, yielding velocity resolutions along the time-of-flight axis of around 6%-9% in the applications presented.

Peripheral neuropathy in adolescents and young adults with type 1 and type 2 diabetes from the SEARCH for Diabetes in Youth follow-up cohort: a pilot study

OBJECTIVE

To estimate the prevalence of and risk factors for diabetic peripheral neuropathy (DPN) in a pilot study among youth participating in the SEARCH for Diabetes in Youth study.

RESEARCH DESIGN AND METHODS

DPN was assessed using the Michigan Neuropathy Screening Instrument (MNSI) (examination for foot abnormalities, distal vibration perception, and ankle reflexes). An MNSI exam (MNSIE) score >2 is diagnostic for DPN.

RESULTS

The MNSIE was completed in 399 subjects, including 329 youth with type 1 diabetes (mean age 15.7 ± 4.3 years, duration 6.2 ± 0.9 years) and 70 with type 2 diabetes (mean age 21.6 ± 4.1 years, duration 7.6 ± 1.8 years). Glycated hemoglobin (A1C) was similar in both groups (8.8 ± 1.8% for type 1 vs. 8.5 ± 2.9% for type 2). The prevalence of DPN was significantly higher in youth with type 2 compared with those with type 1 diabetes (25.7 vs. 8.2%; P < 0.0001). In unadjusted analyses, diabetes type, older age, longer duration of diabetes, increased waist circumference, elevated blood pressure, lower HDL cholesterol, and presence of microalbuminuria (urinary albumin-to-creatinine ratio >30 mg/g) were associated with DPN. The association between diabetes type and DPN remained significant after adjustment for age and sex (odds ratio 2.29 [95% CI 1.05-5.02], P = 0.03).

CONCLUSIONS

DPN prevalence among youth with type 2 diabetes approached rates reported in adult populations with diabetes. Our findings suggest not only that youth with diabetes are at risk for DPN but also that many already show measurable signs of DPN.

Albuminuria according to status of autoimmunity and insulin sensitivity among youth with type 1 and type 2 diabetes

OBJECTIVE

To evaluate whether etiologic diabetes type is associated with the degree of albuminuria in children with diabetes. RESEARCH DESIGN AND METHODS SEARCH: is an observational, longitudinal study of children with diabetes. Youth with newly diagnosed diabetes were classified according to diabetes autoantibody (DAA) status and presence of insulin resistance. We defined insulin resistance as an insulin sensitivity score <25th percentile for the United States general youth population. DAA status was based on positivity for the 65-kD isoform of glutamate decarboxylase and insulinoma-associated protein 2 antigens. The four etiologic diabetes type groups were as follows: DAA(+)/insulin-sensitive (IS) (n = 1,351); DAA(+)/insulin-resistant (IR) (n = 438); DAA(-)/IR (n = 379); and DAA(-)/IS (n = 233). Urinary albumin:creatinine ratio (UACR) was measured from a random urine specimen. Multivariable regression analyses assessed the independent relationship between the four diabetes type groups and magnitude of UACR.

RESULTS

Adjusted UACR means across the four groups were as follows: DAA(+)/IS = 154 μg/mg; DAA(+)/IR = 137 μg/mg; DAA(-)/IR = 257 μg/mg; and DAA(-)/IS = 131 μg/mg (P < 0.005). Only DAA(-)/IR was significantly different. We performed post hoc multivariable regression analysis restricted to the two IR groups to explore the contribution of DAA status and insulin sensitivity (continuous) to the difference in UACR between the IR groups. Only insulin sensitivity was significantly associated with UACR (β = -0.54; P < 0.0001).

CONCLUSIONS

In youth with diabetes, the DAA(-)/IR group had a greater UACR than all other groups, possibly because of the greater magnitude of insulin resistance. Further exploration of the relationships between severity of insulin resistance, autoimmunity, and albuminuria in youth with diabetes is warranted.

Adiponectin and arterial stiffness in youth with type 1 diabetes: the SEARCH for diabetes in youth study

Persons with type 1 diabetes are at increased risk of developing vascular disease. Adiponectin concentrations may play an intermediate role in this process. We sought to determine whether adiponectin is correlated with vascular stiffness in adolescents with type 1 diabetes. Plasma adiponectin, pulse wave velocity (PWV), augmentation index (AIx-75), and brachial distensibility (BrachD) were collected in 225 adolescents. Outcomes were evaluated by sex, and regression models were used to determine whether adiponectin was an independent determinant of arterial stiffness. Males had lower adiponectin levels and stiffer vessels (lower BrachD, p < 0.01) than females. Unadjusted correlations revealed that adiponectin was correlated with BrachD (p < 0.01) but not PWV and AIx-75. After adjustment, adiponectin was not a significant predictor of BrachD. The most consistent predictors of increased stiffness were age, male sex, blood pressure, obesity, and total cholesterol (p < 0.05). Adiponectin's contributions to arterial stiffness appear to be masked by other cardiovascular risk factors in persons with type 1 diabetes.

Mitigating the health impacts of pollution from oceangoing shipping: an assessment of low-sulfur fuel mandates

Concerns about health effects due to emissions from ships have magnified international policy debate regarding low-sulfur fuel mandates for marine fuel. Policy discussions center on setting sulfur content levels and the geographic specification of low-sulfur fuel use. We quantify changes in premature mortality due to emissions from ships under several sulfur emissions control scenarios. We compare a 2012 No Control scenario (assuming 2.7% or 27 000 ppm S) with three emissions control scenarios. Two control scenarios represent cases where marine fuel is limited to 0.5% S (5000 ppm) and 0.1% S (1000 ppm) content, respectively, within 200 nautical miles of coastal areas. The third control scenario represents a global limit of 0.5% S. We apply the global climate model ECHAMSSy-MESSy1-MADE to geospatial emissions inventories to determine worldwide concentrations of particular matter (PM2.5) from ocean going vessels. Using those PM2.5 concentrations in cardiopulmonary and lung cancer concentration-risk functions and population models, we estimate annual premature mortality. Without control, our central estimate is approximately 87 000 premature deaths annually in 2012. Coastal area control scenarios reduce premature deaths by approximately 33 500 for the 0.5% case and approximately 43 500 for the 0.1% case. Where fuel sulfur content is reduced globally to 0.5% S, premature deaths are reduced by approximately 41 200. These results provide important support that global health benefits are associated with low-sulfur marine fuels, and allow for relative comparison of the benefits of alternative control strategies.

Pain management in children with and without cognitive impairment following spine fusion surgery

BACKGROUND

We compared pain assessment and management practices in children with and without cognitive impairment (CI) undergoing spine fusion surgery.

METHODS

The medical records of 42 children (19 with CI and 23 without) were reviewed and data related to demographics, surgery, pain assessment and management, and side-effects were recorded.

RESULTS

Fewer children with CI were assessed for pain on postoperative days (POD) 0-4 compared to those without CI (P < 0.002). Self-report was used for 81% of pain assessments in children without CI, while a behavioural tool was used for 75% of assessments in cognitively impaired children. Children with CI received smaller total opioid doses on POD 1-3 compared to those without CI (P < or = 0.02). Furthermore, children without CI received patient/nurse-controlled analgesia for more postoperative days than children with CI (P=0.02).

CONCLUSION

Our data demonstrate a discrepancy in pain management practices in children with and without CI following spine fusion.

Prediction of outcome after rectus femoris surgery in cerebral palsy: the role of cocontraction of the rectus femoris and vastus lateralis

Rectus femoris surgery was performed on 70 patients with cerebral palsy and stiff-knee gait. Fifty-three patients underwent distal rectus transfer, and 17 patients had distal rectus release with complete muscle mobilization. Gait analysis was performed preoperatively and postoperatively at a minimum of 1 year. Swing-phase peak knee flexion (PKF) was improved in the transfer group, allowing improved foot clearance and more efficient gait (p = 0.04). PKF in swing deteriorated slightly in the release group (p = 0.04). The presence of abnormal swing-phase electromyogram (EMG) activity in the rectus alone or abnormal combined rectus and vastus lateralis activity did not influence the PKF results in either surgery (p < 0.05). The Ely test had no predictive value in identifying patients with abnormal EMG activity (p > 0.05). Preoperative knee range of motion was not a significant variable in determining relative success of rectus surgery. No deleterious effects were observed in stance phase in either group (p > 0.05).

Hemodynamic consequences of continuous arteriovenous hemofiltration

Continuous arteriovenous hemofiltration (CAVH) is an extracorporeal treatment in which fluid, electrolytes, and low and middle molecular weight solutes are removed from the blood by ultrafiltration. It is efficacious in the management of acute or chronic renal failure complicated by fluid overload, and following surgery. In this study, cardiac filling pressures, cardiac indices, and BP were monitored in nine patients. A mean of 7 kg of fluid was removed in ten treatments without the induction of hypotension. In nine of ten treatments, cardiac index increased following fluid removal. An increment in myocardial pump function was noted even in patients with low output heart failure. This treatment differs from dialysis in its ability to remove large fluid volumes without compromising cardiac hemodynamics. In addition, CAVH may have a role in treating volume overload patients with renal insufficiency and heart failure resistant to pharmacologic intervention.

Sodium fluxes during hemodialysis

Three sets of experiments were performed to determine the effect of the dialysate sodium concentration on the sodium balance of patients undergoing maintenance hemodialysis. First, patients were treated with three different dialysate bath sodium concentrations: 125-132 mEq/l (n = 7), 135-140 mEq/l (n = 11) and 145-150 mEq/l (n = 6). We demonstrated that the pretreatment plasma sodium concentration was independent of the sodium concentration of the dialysate used. Second, the plasma sodium concentration available for diffusion during the treatment was calculated from the plasma sodium concentration and the plasma proteins. The accuracy of this calculation was demonstrated by comparing the predicted value with the concentration of sodium measured in an ultrafiltrate obtained at minimal filtration fraction. Third, the sodium fluxes using a hypernatremic or hyponatremic dialysate were calculated for 100 ml of plasma going through the dialyzer. At steady state, no significant differences in net sodium fluxes were demonstrated between hyper- and hyponatremic dialysis.

Renal hemodynamic changes in humans. Response to protein loading in normal and diseased kidneys

This study was undertaken to define the renal hemodynamic changes that mediate the acute response to an oral protein load. Three groups of subjects were studied: (1) disease-free subjects; (2) patients with chronic renal disease of various causes, except for diabetes mellitus, documented by history and/or renal biopsy; and (3) patients with diabetes mellitus, that is, a history of hyperglycemia requiring antihyperglycemic therapy. All subjects were studied before (baseline) and after (test) ingestion of a protein load. Glomerular filtration rate and effective renal plasma flow were evaluated by inulin and para-amino-hippurate, respectively. In the disease-free subjects, the mean baseline glomerular filtration rate and renal plasma flow were 122 +/- 10 ml/minute/1.73 m2 and 644 +/- 64 ml/minute/1.73 m2, whereas test glomerular filtration rate and renal plasma flow were 151 +/- 15 ml/minute/1.73 m2 and 791 +/- 111 ml/minute/1.73 m2, respectively. In patients with chronic renal disease, the test glomerular filtration rate and renal plasma flow were related to the severity of the disease. The more severe the disease, the lower the absolute test values and the smaller the increment from baseline to test values. Patients with diabetes mellitus had a paradoxic response to ingestion of a protein load. Glomerular filtration rate fell while renal plasma flow remained unchanged. This response was observed in all diabetic patients regardless of the type of diabetes or whether clinical evidence of diabetic nephropathy was absent, minimal, or severe.

Short-term protein loading in assessment of patients with renal disease

The effect of short-term protein loading on the glomerular filtration rate in normal persons and patients with renal disease was evaluated. Previous studies have demonstrated that in healthy subjects, protein loading results in an increased glomerular filtration rate. By determining the glomerular filtration rate preceding (baseline glomerular filtration rate) and following (test glomerular filtration rate) oral protein loading, it was possible to define (1) the filtration capacity (test glomerular filtration rate) and (2) the renal reserve (test glomerular filtration rate - baseline glomerular filtration rate) of the kidney. In normal persons, filtration capacity averaged 157 +/- 13 ml per minute and renal reserve 34 ml per minute. The test glomerular filtration rate was reproducible and independent of protein intake, whereas baseline glomerular filtration rate was significantly influenced by diet. Patients with renal disease were found to have a reduced renal reserve and/or a diminished filtration capacity. The reduction in filtration capacity appears to correlate with the damage sustained by the organ. It is suggested that an abnormal response to protein loading in renal disease may herald the fall in the baseline glomerular filtration rate and the rise in plasma creatinine level.

Renal functional reserve in humans. Effect of protein intake on glomerular filtration rate

This study was designed to investigate the effect of protein intake on glomerular filtration rate, and to demonstrate and evaluate the functional reserve of the kidney. Normal subjects ingesting a protein diet had a significantly higher creatinine clearance than a comparable group of normal subjects ingesting a vegetarian diet. A progressive increment in protein intake in normal volunteers resulted in a significant increase in creatinine clearance. Diurnal variations in creatinine clearance were found. These daily variations correlated well with the periods of food intake. The capacity of the kidney to increase its level of function with protein intake suggests a renal function reserve. In short-term studies, the effect of a protein load on glomerular filtration rate was evaluated. Normal subjects showed an increase in glomerular filtration rate two and a half hours after protein load to a maximal glomerular filtration rate of 171.0 +/- 7.7 ml per minute. In patients with a reduced number of nephrons, renal functional reserve may be diminished or absent.

Continuous arteriovenous hemofiltration in the critically ill patient. Clinical use and operational characteristics

Continuous arteriovenous hemofiltration is an extracorporeal technique for the treatment of fluid overload and electrolyte disturbances and for the removal of urea nitrogen. This technique is especially applicable in critically ill patients with hemodynamic instability. A special filter and modified hemodialysis blood lines can easily and rapidly be attached to a patient. No special blood access is needed. Fluids and solutes are removed from the patient by ultrafiltration. A net filtration pressure inside the filter causes an ultrafiltrate to form. The extracorporeal circuit can be kept in place for hours or days.