Comparative analysis of the skim milk and milk fat globule membrane proteomes produced by Jersey cows grazing pastures with different plant species diversity.

The objective of this experiment was to identify and characterize the bovine milk proteome within the skim milk fraction and milk fat globule membrane (MFGM)-associated fraction from 16 organically certified lactating Jersey cows after a short term of grazing pastures with or without annual forage crops (AFC). Cows were offered a partial mixed ration (∼60% of dry matter intake) and approximately 40% of their total dry matter intake as herbage. Eight cows were offered a cool-season grass-legume herbage (GLH), which included orchardgrass (Dactylis glomerata), timothy (Phleum pratense), Kentucky bluegrass (Poa pratensis), and white clover (Trifolium repens). The other 8 cows were offered the same GLH strip-tilled with the AFC, including oat (Avena sativa), millet (Pennisetum glaucum), teff (Eragrostis tef), buckwheat (Fagopyrum esculentum), and chickling vetch (Lathyrus sativus). Milk samples were collected from each cow during a.m. and p.m. milkings on d 19 to 21 of grazing, and composite milk samples per cow were analyzed for (1) the high-abundance milk protein profile, (2) the skim milk low-abundance protein-enriched proteome, and (3) the MFGM proteome. Of the 443 proteins identified in the skim and MFGM proteomes, 433 were included in statistical analysis, including 68 proteins identified in the skim milk fraction and 365 in the MFGM-associated fraction. Analysis of the skim and MFGM proteomes encompassed unique gene ontology profiles and proportions of functional classifications. In response to diet, αS1-casein as well as 8 low-abundance proteins were present in higher concentration or abundance in milk from cows grazing the GLH strip-tilled with the AFC compared with milk from cows grazing GLH, suggesting that even short-term grazing of pastures including some AFC may affect the milk proteome.

Ratio of dietary rumen degradable protein to rumen undegradable protein affects nitrogen partitioning but does not affect the bovine milk proteome produced by mid-lactation Holstein dairy cows.

Little is known about the bovine milk proteome or whether it can be affected by diet. The objective of this study was to determine if the dietary rumen degradable protein (RDP):rumen undegradable protein (RUP) ratio could alter the bovine milk proteome. Six Holstein cows (parity: 2.5 ± 0.8) in mid lactation were blocked by days in milk (80 ± 43 d in milk) and milk yield (57.5 ± 6.0 kg) and randomly assigned to treatment groups. The experiment was conducted as a double-crossover design consisting of three 21-d periods. Within each period, treatment groups received diets with either (1) a high RDP:RUP ratio (RDP treatment: 62.4:37.6% of crude protein) or (2) a low RDP:RUP ratio (RUP treatment: 51.3:48.7% of crude protein). Both diets were isonitrogenous and isoenergetic (crude protein: 18.5%, net energy for lactation: 1.8 Mcal/kg of dry matter). To confirm N and energy status of cows, dry matter intake was determined daily, rumen fluid samples were collected for volatile fatty acid analysis, blood samples were collected for plasma glucose, ß-hydroxybutyrate, urea nitrogen, and fatty acid analysis, and total 24-h urine and fecal samples were collected for N analysis. Milk samples were collected to determine the general milk composition and the protein profile. Milk samples collected for high-abundance protein analysis were subjected to HPLC analysis to determine the content of α-casein, ß-casein, and κ-casein, as well as α-lactalbumin and ß-lactoglobulin. Samples collected for low-abundance protein analysis were fractionated, enriched using ProteoMiner treatment, and separated using sodium dodecyl sulfate-PAGE. After excision and digestion, the peptides were analyzed using liquid chromatography (LC) tandem mass spectrometry (MS/MS). The LC-MS/MS data were analyzed using PROC GLIMMIX of SAS (version 9.4, SAS Institute Inc., Cary, NC) and adjusted using the MULTTEST procedure. All other parameters were analyzed using PROC MIXED of SAS. No treatment differences were observed in dry matter intake, milk yield, general milk composition, plasma parameters, or rumen volatile fatty acid concentrations, indicating no shift in total energy or protein available. Milk urea N and plasma urea N concentrations were higher in the RDP group, indicating some shift in N partitioning due to diet. A total of 595 milk proteins were identified, with 83% of these proteins known to be involved in cellular processes. Although none of the low-abundance proteins identified by LC-MS/MS were affected by diet, feeding a diet high in RUP decreased ß-casein, κ-casein, and total milk casein concentration. Further investigations of the interactions between diet and the milk protein profile are needed to manipulate the milk proteome using diet.

Exploration of the bovine colostrum proteome and effects of heat treatment time on colostrum protein profile.

Heat treatment of colostrum is performed on modern dairy farms to reduce pathogenic contamination before hand-feeding the colostrum to newborn calves; however, limited data are available concerning effects of heat treatment on biologically active proteins in colostrum. The objective of this exploratory study was to investigate effects of heat treatment and length of heat treatment on colostrum protein profile. Colostrum samples were collected from Holstein cows within 12 h after parturition and assigned to the following groups: heat treatment at 60°C for 0 (untreated control), 30, 60, or 90 min. Samples were fractionated using acid precipitation, followed by ultracentrifugation and ProteoMiner (Bio-Rad Laboratories, Hercules, CA) treatment, and tandem-mass tagging was used to comparatively assess the low abundance protein profile. A total of 162 proteins were identified with more than 2 peptides in the low abundance protein enriched fraction. Of these, 62 differed in abundance by more than 2-fold in heat-treated samples compared with the unheated control. The majority of proteins affected by heat treatment were involved in immunity, enzyme function, and transport-related processes; affected proteins included lactadherin, chitinase-3-like protein 1, and complement component C9. These results provide a foundation for further research to determine optimum heat treatment practices to ensure newborn calves are fed colostrum-containing proteins with the highest nutritional and biological value.

Potential-based methodology for active sound control in three dimensional settings.

This paper extends a potential-based approach to active noise shielding with preservation of wanted sound in three-dimensional settings. The approach, which was described in a previous publication [Lim et al., J. Acoust. Soc. Am. 129(2), 717-725 (2011)], provides several significant advantages over conventional noise control methods. Most significantly, the methodology does not require any information including the characterization of sources, impedance boundary conditions and surrounding medium, and that the methodology automatically differentiates between the wanted and unwanted sound components. The previous publication proved the concept in one-dimensional conditions. In this paper, the approach for more realistic conditions is studied by numerical simulation and experimental validation in three-dimensional cases. The results provide a guideline to the implementation of the active shielding method with practical three-dimensional conditions. Through numerical simulation it is demonstrated that while leaving the wanted sound unchanged, the developed approach offers selective volumetric noise cancellation within a targeted domain. In addition, the method is implemented in a three-dimensional experiment with a white noise source in a semi-anechoic chamber. The experimental study identifies practical difficulties and limitations in the use of the approach for real applications.

Biochemical characterization of the cell-biomaterial interface by quantitative proteomics.

Surface topography and texture of cell culture substrata can affect the differentiation and growth of adherent cells. The biochemical basis of the transduction of the physical and mechanical signals to cellular responses is not well understood. The lack of a systematic characterization of cell-biomaterial interaction is the major bottleneck. This study demonstrated the use of a novel subcellular fractionation method combined with quantitative MS-based proteomics to enable the robust and high-throughput analysis of proteins at the adherence interface of Madin-Darby canine kidney cells. This method revealed the enrichment of extracellular matrix proteins and membrane and stress fibers proteins at the adherence surface, whereas it shows depletion of extracellular matrix belonging to the cytoplasmic, nucleus, and lateral and apical membranes. The asymmetric distribution of proteins between apical and adherence sides was also profiled. Apart from classical proteins with clear involvement in cell-material interactions, proteins previously not known to be involved in cell attachment were also discovered.

Multi-domain active sound control and noise shielding.

This paper describes an active sound control methodology based on difference potentials. The main feature of this methodology is its ability to automatically preserve "wanted" sound within a domain while cancelling "unwanted" noise from outside the domain. This method of preservation of the wanted sounds by active shielding control is demonstrated with various broadband and realistic sound sources such as human voice and music in multiple domains in a one-dimensional enclosure. Unlike many other conventional active control methods, the proposed approach does not require the explicit characterization of the wanted sound to be preserved. The controls are designed based on the measurements of the total field on the boundaries of the shielded domain only, which is allowed to be multiply connected. The method is tested in a variety of experimental cases. The typical attenuation of the unwanted noise is found to be about 20 dB over a large area of the shielded domain and the original wanted sound field is preserved with errors of around 1 dB and below through a broad frequency range up to 1 kHz.

Relationships among subjective and objective measures of adherence to oral antipsychotic medications.

OBJECTIVE: The most common ways of assessing adherence to oral antipsychotic medications in research and in clinical practice are self-report and physician report. This prospective study examined the agreement among measures of adherence to oral antipsychotic medications among 52 outpatients with schizophrenia. METHODS: Participants were assessed at baseline during a visit to their outpatient clinic and followed for 12 weeks. Adherence was assessed by using subjective measures (self-report and physician report) and objective measures (pill counts conducted in the home, electronic monitoring, and blood plasma concentrations). Electronic monitoring was used as an imperfect standard against which other methods were judged. RESULTS: Data from pill counts and from electronic monitoring were strongly correlated (r(k)=.61). Self-report and physicians' ratings of compliance were weakly correlated with pill count and electronic monitoring when compliance scores were examined with rank-order correlations (r(k)=.18-.32). When the sample was dichotomized into adherent and nonadherent groups on the basis of electronic monitoring or pill count (at least 80% adherent), neither physicians nor patients identified adherent behavior (kappa

Pharmacokinetics of Phenobarbital in Microenema Via Macy Catheter Versus Suppository.

CONTEXT: The oral route is compromised for nearly all patients approaching death. When agitation, seizures, or other intractable symptoms occur, a quick, discreet, comfortable, and effective alternate route for medication delivery that is easy to administer in the home setting is highly desirable. OBJECTIVES: To characterize the early absorption profile, variability, and comfort of phenobarbital given in microenema suspensions delivered via the Macy Catheter(®) (MC) vs. the same dose given via suppository. METHODS: This was a randomized, open-label, crossover study comparing the early absorption profile of equal doses of phenobarbital administered rectally in three treatment phases: phenobarbital suppository and two different microenemas with phenobarbital tablets crushed and suspended in 6 mL (MC-6) or 20 mL (MC-20) of tap water. RESULTS: Mean plasma phenobarbital concentrations at 10 minutes were 12× higher for MC-20 and 8× higher for MC-6 compared to suppository. Concentrations achieved in 30 minutes via MC-20 took almost three hours to achieve with suppository. Mean AUC values were higher for MC-20 and MC-6 (82% and 46%, respectively) vs. suppository (P < 0.05). There was less variability in absorption for MC-20 and MC-6 (1.4- to 1.9-fold difference) compared to a 4.4-fold difference via suppository. MC administrations were reported as "not uncomfortable" compared to suppositories, which were reported as "mildly uncomfortable" (P < 0.05). CONCLUSION: These results suggest phenobarbital oral tablets crushed and suspended in water and administered via the MC is superior to suppository in delivering the medication reliably and rapidly.

Odors elicit three different oscillations in the turtle olfactory bulb.

We measured the spatiotemporal aspects of the odor-induced population response in the turtle olfactory bulb using a voltage-sensitive dye, RH414, and a 464-element photodiode array. In contrast with previous studies of population activity using local field potential recordings, we distinguished four signals in the response. The one called DC covered almost the entire area of the olfactory bulb; in addition, three oscillations, named rostral, middle, and caudal according to their locations, occurred over broad regions of the bulb. In a typical odor-induced response, the DC signal appeared almost immediately after the start of the stimulus, followed by the middle oscillation, the rostral oscillation, and last, the caudal oscillation. The initial frequencies of the three oscillations were 14.1, 13.0, and 6.6 Hz, respectively. When the rostral and caudal oscillations occurred together, their frequencies differed by a factor of 1.99 +/- 0.01. The following evidence suggests that the four signals are functionally independent: (1) in different animals some signals could be easily detected whereas others were undetectable; (2) the four signals had different latencies and frequencies; (3) the signals occurred in different locations and propagated in different directions; (4) the signals responded differently to changes in odor concentration; (5) the signals had different shapes; and (6) the rostral and caudal signals added in a simple, linear manner in regions where the location of the two signals overlapped. However, the finding that the frequency of the rostral oscillation is precisely two times that of the caudal oscillation suggests a significant relationship between the two. The location of the caudal oscillation in the bulb changed from cycle to cycle, implying that different groups of neurons are active in different cycles. This result is consistent with the earlier findings in the olfactory system of the locust (). Our results suggest an additional complexity of parallel processing of olfactory input by multiple functional population domains.

Control of cell migration direction by inducing cell shape asymmetry with patterned topography.

In this study, we explored the concept of introducing asymmetry to cell shapes by patterned cell culture substrates, and investigated the consequence of this induced asymmetry to cell migration behaviors. Three patterns, named "Squares", "Grating", and "Arcs" were fabricated, representing different levels of rotational asymmetry. Using time-lapse imaging, we systematically compared the motility and directionality of mouse osteoblastic cells MC3T3-E1 cultured on these patterns. Cells were found to move progressively faster on "Arcs" than on "Grating", and cells on "Squares" were the slowest, suggesting that cell motility correlates with the level of rotational asymmetry of the repeating units of the pattern. Among these three patterns, on the "Arcs" pattern, the least symmetrical one, cells not only moved with the highest velocity but also the strongest directional persistence. Although this enhanced motility was not associated with the detected number of focal adhesion sites in the cells, the pattern asymmetry was reflected in the asymmetrical cell spreading. Cells on the "Arcs" pattern consistently displayed larger cytoplasmic protrusion on one side of the cell. This asymmetry in cell shape determined the direction and speed of cell migration. These observations suggest that topographical patterns that enhance the imbalance between the leading and trailing fronts of adherent cells will increase cell speed and control movement directions. Our discovery shows that complex cell behaviors such as the direction of cell movement are influenced by simple geometrical principles, which can be utilized as the design foundation for platforms that guide and sort cultured cells.

The cell envelope proteome of Aggregatibacter actinomycetemcomitans.

The cell envelope of gram-negative bacteria serves a critical role in maintenance of cellular homeostasis, resistance to external stress, and host-pathogen interactions. Envelope protein composition is influenced by the physiological and environmental demands placed on the bacterium. In this study, we report a comprehensive compilation of cell envelope proteins from the periodontal and systemic pathogen Aggregatibacter actinomycetemcomitans VT1169, an afimbriated serotype b strain. The urea-extracted membrane proteins were identified by mass spectrometry-based shotgun proteomics. The membrane proteome, isolated from actively growing bacteria under normal laboratory conditions, included 648 proteins representing 27% of the predicted open reading frames in the genome. Bioinformatic analyses were used to annotate and predict the cellular location and function of the proteins. Surface adhesins, porins, lipoproteins, numerous influx and efflux pumps, multiple sugar, amino acid and iron transporters, and components of the type I, II and V secretion systems were identified. Periplasmic space and cytoplasmic proteins with chaperone function were also identified. A total of 107 proteins with unknown function were associated with the cell envelope. Orthologs of a subset of these uncharacterized proteins are present in other bacterial genomes, whereas others are found exclusively in A. actinomycetemcomitans. This knowledge will contribute to elucidating the role of cell envelope proteins in bacterial growth and survival in the oral cavity.

Solenin, a novel protein with translation-inhibiting activity from the traditional Chinese medicinal fish, the sea dragon Solenognathus hardwickii.

A single-chained protein designated solenin was isolated from Solenognathus hardwickii, a fish used as traditional Chinese medicinal material. Solenin was capable of inhibiting translation in a cell-free rabbit reticulocyte lysate system with an IC(50) of 2 microM and expressing a ribonuclease activity of 0.8U/mg toward yeast transfer RNA, but it lacked N-glycosidase activity characteristic of ribosome inactivating proteins Solenin exhibited a molecular weight of 18kDa and possessed an N-terminal sequence AHDAEVNEVKAQVAA. The protein was adsorbed on three types of chromatographic media: Affi-gel blue gel, CM-Sepharose and Mono S. It was devoid of antifungal and lectin activities.

Pharmacodynamics and pharmacokinetics of haloperidol and reduced haloperidol in schizophrenic patients.

Twelve male chronic schizophrenic inpatients, neuroleptic-free for at least 4 weeks, were given an oral test dose of 10 mg haloperidol (HAL) and reduced HAL (RHAL) in a random order, with a 2-week interval. Two weeks after the last test dose, the patients were given HAL, 5 mg orally twice daily for 7 days. Blood samples were drawn at baseline and between 0.5 and 24 hr after the test doses, and during HAL treatment as well. Plasma drug concentrations and homovanillic acid (HVA) levels were measured with high-performance liquid chromatography using electrochemical detection. HAL, but not RHAL, produced increments in plasma HVA (pHVA) levels at 24 hr after a test dose. pHVA levels remained higher than baseline during HAL treatment. Detectable interconversion between HAL and RHAL was observed in eight patients. The capacity of the reductive drug-metabolizing enzyme system, however, was greater than that of the oxidative processes. The plasma RHAL:HAL ratios on days 6 and 7 were higher than and positively correlated with those at Tmax after a single dose of HAL and were negatively correlated with the HAL:RHAL ratios at Tmax after a single dose of RHAL. Thus, both reductive and oxidative drug-metabolizing systems probably contribute to individual differences in plasma RHAL:HAL ratios in HAL-treated schizophrenic patients.

Disposition and covalent binding of ibuprofen and its acyl glucuronide in the elderly.

Ibuprofen is an over-the-counter nonsteroidal anti-inflammatory drug with a low incidence of severe adverse reactions. It is metabolized by oxidation to carboxyibuprofen and hydroxyibuprofen and by conjugation to an acyl glucuronide. In vitro studies have indicated that ibuprofen glucuronide is labile and reactive, forming covalent adducts with proteins. To verify the formation of ibuprofen-protein adducts in vivo, the pharmacokinetics of ibuprofen glucuronide and its covalent binding to plasma proteins were studied in five elderly patients who received long-term administration of oral doses of ibuprofen. Plasma levels of ibuprofen glucuronide were low relative to those of ibuprofen; the ratio of area under the plasma concentration versus time curve for the glucuronide relative to the parent drug was only 4%. Covalent binding of ibuprofen to plasma protein was observed in all patients, correlating well with the area under the plasma concentration versus time curve of ibuprofen glucuronide (r = 0.966). Compared with reports for other nonsteroidal anti-inflammatory drugs that form acyl glucuronides, plasma levels of ibuprofen-protein adduct are low during long-term administration. The observed lower reactivity in vivo is probably attributable to the greater stability of ibuprofen glucuronide relative to other acyl glucuronides.

The pharmacokinetics of teicoplanin in varying degrees of renal function.

The pharmacokinetics of teicoplanin, a new glycopeptide antibiotic with activity against aerobic gram-positive bacteria, were characterized after intravenous administration of a single 3 mg/kg dose in five healthy volunteers and six patients with various degrees of stable renal insufficiency. Serum and urine samples were collected during a 15-day period and drug concentrations were assayed microbiologically. The mean elimination half-life of teicoplanin was 162.6 +/- 69.8 hours in healthy volunteers and was prolonged with decreased renal function. The mean plasma and renal clearances of teicoplanin in healthy subjects were 11.4 +/- 1.5 ml/min and 10.0 +/- 1.0 ml/min, respectively. Both values decreased in patients with renal failure and correlated significantly with measured creatinine clearances (r2 = 0.938 and 0.884, respectively). A nomogram for dosage adjustment in patients with varying degrees of renal failure is presented.

Interindividual variabilities in haloperidol interconversion and the reduced haloperidol/haloperidol ratio.

Metabolism of haloperidol in humans includes N-dealkylation to inactive metabolites and reduction to reduced haloperidol; reduced haloperidol is also oxidized back to haloperidol. A single 0.5 mg/kg (0.00133 mmol/kg) oral dose of haloperidol and reduced haloperidol was administered to seven Chinese schizophrenics in a randomized crossover manner separated by a 2-week interval. The clearance values for the different metabolic pathways of haloperidol and reduced haloperidol were determined. There were differences up to 10-fold in both oxidation and reduction capacities. There were also interindividual variabilities in the elimination of reduced haloperidol (0.37 +/- 0.20 L/hr/kg) and the N-dealkylation pathway (0.74 +/- 0.36 L/hr/kg). Four weeks after the single-dose study, the same patients also received haloperidol (10 mg) twice daily for 4 weeks. The reduced haloperidol to haloperidol concentration ratio (0.40 +/- 0.16) after the 4-week therapy is related to individual variabilities in the interconversion process and the N-dealkylation pathway of haloperidol.

Correlation of cytochrome P450 (CYP) 1A2 activity using caffeine phenotyping and olanzapine disposition in healthy volunteers.

Olanzapine has previously been shown to have predominant metabolism by cytochrome (CYP) P450 1A2. Caffeine has been shown to provide an accurate phenotypic probe for measuring CYP1A2 activity. The purpose of this study is to determine if a significant correlation exists between olanzapine disposition and caffeine metabolic ratios. Subjects were phenotyped for CYP1A2 activity with caffeine probe methodology. After 200-mg caffeine administration, blood (4 h), saliva (6 and 10 h), and urine (8 h total) were collected for high-performance liquid chromatography (HPLC) analysis of caffeine and its metabolites.CYP1A2 activity was measured as plasma (PMR(4 h)), saliva (SMR(6 h) and SMR(10 h)), and three urinary metabolic (UMR1(8 h), UMR2(8 h), and UMR3(8 h)) ratios. Each of the 14 healthy nonsmokers (13 male) received a single 10 mg olanzapine dose after which blood was collected for HPLC determination of olanzapine concentrations at predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 24, 48, 72, 96, and 120 h postdose. Olanzapine pharmacokinetic parameters in this study were similar to those previously published. All caffeine metabolic ratios (PMR(4 h), SMR(6 h), SMR(10 h), UMR1(8 h), and UMR2(8 h)) significantly correlated with each other (p <0.001) except for UMR3(8 h), which did not correlate. A significant correlation (p <0.05) was also found between olanzapine clearance and PMR(4 h) (r=0.701), SMR(6 h) (r=0.644), SMR(10 h) (r=0.701), UMR1(8 h) (r=0.745), and UMR2(8 h) (r=0.710). A negative correlation was observed between olanzapine clearance and UMR3(8 h) (r=-0.029, p=NS). A significant correlation was found between olanzapine clearance and various caffeine metabolic ratios. Interpatient variability in CYP1A2 activity may explain the wide interpatient variability in olanzapine disposition. Compounds that modulate CYP1A2 activity may be expected to alter olanzapine pharmacokinetics accordingly.

Drug interactions in hypertensive patients. Pharmacokinetic, pharmacodynamic and genetic considerations.

Antihypertensive treatment has proven benefits, and the number of patients being treated with these drugs is significant. Hypertensive patients may have other medical illnesses for which they receive medications, and interactions between antihypertensive agents and other drugs is likely. Some of these interactions may lead to undesirable effects or even loss of blood pressure control. However, drug interactions can also be beneficial when 2 antihypertensive drugs with different pharmacological actions are prescribed in combination and with a clear therapeutic objective in mind. Clinicians should be aware of the mechanisms and the consequences of the different types of interaction in hypertensive patients, so that a desired pharmacological response can be achieved with the fewest side effects in the patients.

Hypoxia, arterial pH and theophylline disposition.

Theophylline is a bronchodilator used extensively in the management of obstructive pulmonary disease. Factors implicated in altered theophylline clearance include smoking, age, concomitant drug intake, liver disease and left ventricular heart failure. However, evidence now suggests that theophylline clearance may be altered by changes in severity of the pulmonary obstruction, hypoxia and variation in arterial pH. The in vitro disposition of theophylline has been evaluated in isolated rat livers and mouse hepatocytes. In vivo studies have assessed the metabolism of theophylline under hypoxia in rats, rabbits and dogs. In isolated mouse hepatocytes and rat livers, low oxygen concentrations resulted in higher theophylline concentrations, a longer elimination half-life and a decrease in the production of the metabolite 1,3-dimethyl uric acid, suggesting impaired metabolism of theophylline. In rabbits, hypoxia, hypercapnia and respiratory acidosis decreased total body clearance and increased plasma theophylline concentrations. On the other hand, experiments involving dogs showed no significant changes in theophylline concentrations or pharmacokinetic parameters with hypoxia. At present, animal studies remain inconclusive. This can be attributed to the use of different animal models and variations in study methodology, including the extent and duration of hypoxia and acidaemia, concurrent acid-base disorders such as hypercapnia, as well as the severity of pulmonary obstruction. Human studies assessing alterations in theophylline disposition secondary to the hypoxia present in pulmonary disease are few and include mostly case reports and observational studies. There is evidence suggesting decreased theophylline clearance and protein binding during acute illness and some consensus can be achieved using case reports and controlled studies. There is additional evidence that drug clearance decreases with age and that elderly patients may have a decreased theophylline clearance at baseline. However, the most obvious markers appear to be the severity of pulmonary disease and the rate of change in the patient's condition. Caution should be exercised when administering theophylline to elderly patients with chronic obstructive pulmonary disease presenting with acute exacerbations of a concomitant respiratory illness, as these patients appear to be most likely to exhibit altered theophylline metabolism. Therefore, they would be at increased risk for toxicity should conventional dosages be used during an acute respiratory event.