The impact of neoadjuvant systemic treatment on postoperative complications in breast cancer surgery.

PURPOSE: The aim of the study was to analyze the impact of neoadjuvant systemic treatment (NST) on postoperative complications and the beginning of adjuvant treatment. METHODS: This study includes data from a prospectively maintained database including patients with breast cancer (BC) stage I-IV with or without NST undergoing breast cancer surgery between January 2010 and September 2021. RESULTS: Out of 517 enrolled patients, 77 received NST, 440 had primary breast surgery. After NST patients underwent surgery after a meantime of 34 days (26.5-40 days). No statistical significance could be found comparing the complication grading according to the Clavien Dindo classification. The complications were most frequently rated as grade 3b. There were no complications with grade 4 or higher. When differentiating into short and long-term, the overall rate of short-term complications was 20.3% with no significant difference between the two groups (20.8% vs. 20.2%). Regarding long-term complications, there was more impairment of shoulder mobility (26.0% vs. 9.5%, p ≤ 0.001) and chronic pain (42.9% vs. 28.6%, p ≤ 0.016) for patients with NST. The beginning of the administration of the adjuvant treatment was comparable in both groups (46.3 days vs. 50.5 days). CONCLUSION: In our cohort, complications between both groups were comparable according to Clavien Dindo. This study shows that NST has no negative impact on postoperative short-term complications and most importantly did not lead to a delay of the beginning of adjuvant treatment. Therefore, NST can be safely admitted, even when followed by extensive breast reconstruction surgery.

The impact of age on patient-reported outcomes after oncoplastic versus conventional breast cancer surgery.

PURPOSE: Some studies have indicated age-specific differences in quality of life (QoL) among breast cancer (BC) patients. The aim of this study was to compare patient-reported outcomes after conventional and oncoplastic breast surgery in two distinct age groups. METHODS: Patients who underwent oncoplastic and conventional breast surgery for stage I-III BC, between 6/2011-3/2019, were identified from a prospectively maintained database. QoL was prospectively evaluated using the Breast-Q questionnaire. Comparisons were made between women < 60 and ≥ 60 years. RESULTS: One hundred thirty-three patients were included. Seventy-three of them were ≥ 60 years old. 15 (20.5%) of them received a round-block technique (RB) / oncoplastic breast-conserving surgeries (OBCS), 10 (13.7%) underwent nipple-sparing mastectomies (NSM) with deep inferior epigastric perforator flap (DIEP) reconstruction, 23 (31.5%) underwent conventional breast-conserving surgeries (CBCS), and 25 (34.2%) received total mastectomy (TM). Sixty patients were younger than 60 years, 15 (25%) thereof received RB/OBCS, 22 (36.7%) NSM/DIEP, 17 (28.3%) CBCS, and 6 (10%) TM. Physical well-being chest and psychosocial well-being scores were significantly higher in older women compared to younger patients (88.05 vs 75.10; p < 0.001 and 90.46 vs 80.71; p = 0.002, respectively). In multivariate linear regression, longer time intervals had a significantly positive effect on the scales Physical Well-being Chest (p = 0.014) and Satisfaction with Breasts (p = 0.004). No significant results were found concerning different types of surgery. CONCLUSION: Our findings indicate that age does have a relevant impact on postoperative QoL. Patient counseling should include age-related considerations, however, age itself cannot be regarded as a contraindication for oncoplastic surgery.

Genetic Variation/Evolution and Differential Host Responses Resulting from In-Patient Adaptation of Mycobacterium avium.

Members of the Mycobacterium avium complex (MAC) are characterized as nontuberculosis mycobacteria and are pathogenic mainly in immunocompromised individuals. MAC strains show a wide genetic variability, and there is growing evidence suggesting that genetic differences may contribute to a varied immune response that may impact the infection outcome. The current study aimed to characterize the genomic changes within M.avium isolates collected from single patients over time and test the host immune responses to these clinical isolates. Pulsed-field gel electrophoresis and whole-genome sequencing were performed on 40 MAC isolates isolated from 15 patients at the Department of Medical Microbiology at St. Olavs Hospital in Trondheim, Norway. Isolates from patients (patients 4, 9, and 13) for whom more than two isolates were available were selected for further analysis. These isolates exhibited extensive sequence variation in the form of single-nucleotide polymorphisms (SNPs), suggesting that M. avium accumulates mutations at higher rates during persistent infections than other mycobacteria. Infection of murine macrophages and mice with sequential isolates from patients showed a tendency toward increased persistence and the downregulation of inflammatory cytokines by host-adapted M. avium strains. The study revealed the rapid genetic evolution of M. avium in chronically infected patients, accompanied by changes in the virulence properties of the sequential mycobacterial isolates.

Nose to back: compatibility of nasal chondrocytes with environmental conditions mimicking a degenerated intervertebral disc.

Nasal chondrocytes (NCs) have gained increased recognition for cartilage tissue regeneration. To assess NCs as a source for cell therapy treatment of intervertebral disc (IVD) degeneration, tissue-forming properties of NCs under physiological conditions mimicking the degenerated IVD were compared to those of mesenchymal stromal cells (MSCs) and articular chondrocytes (ACs), two cell sources presently used in clinical trials. Cells were cultured in a combination of low glucose, hypoxia, acidity and inflammation for 28 d. Depending on the conditions, cells were either cultured in the absence of instructive growth factors or underwent chondrogenic instructional priming by addition of transforming growth factor ß1 (TGFß1) for the first 7 d. Histology, immunohistochemistry, biochemistry, enzyme-linked immunosorbent assay (ELISA) and quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) analyses demonstrated limited cell maintenance and accumulation of cartilaginous extracellular matrix for MSCs in IVD conditions. ACs maintained a steady accumulation of glycosaminoglycans (GAGs) throughout all non-acidic conditions, with and without priming, but could not synthesise type II collagen (Col2). NCs accumulated both GAGs and Col2 in all non-acidic conditions, independent of priming, whereas MSCs strongly diminished their GAG and Col2 accumulation in an inflamed environment. Supplementation with inflammatory cytokines or an acidic environment affected NCs to a lower extent than ACs or MSCs. The data, overall indicating that in an inflamed IVD environment NCs were superior to ACs and MSCs, encourage further assessment of NCs for treatment of degenerative disc disease.

Studying the Dynamics of Relativistic Laser-Plasma Interaction on Thin Foils by Means of Fourier-Transform Spectral Interferometry.

We apply Fourier-transform spectral interferometry (FTSI) to study the interaction of intense laser pulses with ultrathin targets. Ultrathin submicrometer-thick solid CH targets were shot at the PHELIX laser facility with an intensity in the mid to upper 10^{19} W/cm^{2} range using an innovative double-pulse structure. The transmitted pulse structure was analyzed by FTSI and shows a transition from a relativistic transparency-dominated regime for targets thinner than 500 nm to a hole-boring-dominated laser-plasma interaction for thicker targets. The results also confirm that the inevitable preplasma expansion happening during the rising slope of the pulse, a few picoseconds before the maximum of the pulse is reached, cannot be neglected and plays a dominant role in laser-plasma interaction with ultrathin solid targets.

Bacterial biofilms and capsular contracture in patients with breast implants.

BACKGROUND: It has been hypothesized that bacterial biofilms on breast implants may cause chronic inflammation leading to capsular contracture. The association between bacterial biofilms of removed implants and capsular contracture was investigated. METHODS: Breast implants explanted between 2006 and 2010 at five participating centres for plastic and reconstructive surgery were investigated by sonication. Bacterial cultures derived from sonication were correlated with patient, surgical and implant characteristics, and the degree of capsular contracture. RESULTS: The study included 121 breast implants from 84 patients, of which 119 originated from women and two from men undergoing gender reassignment. Some 50 breast prostheses were implanted for reconstruction, 48 for aesthetic reasons and 23 implants were used as temporary expander devices. The median indwelling time was 4·0 (range 0·1-32) years for permanent implants and 3 (range 1-6) months for temporary devices. Excluding nine implants with clinical signs of infection, sonication cultures were positive in 40 (45 per cent) of 89 permanent implants and in 12 (52 per cent) of 23 temporary devices. Analysis of permanent implants showed that a positive bacterial culture after sonication correlated with the degree of capsular contracture: Baker I, two of 11 implants; Baker II, two of ten; Baker III, nine of 23; and Baker IV, 27 of 45 (P < 0·001). The most frequent organisms were Propionibacterium acnes (25 implants) and coagulase-negative staphylococci (21). CONCLUSION: Sonication cultures correlated with the degree of capsular contracture, indicating the potential causative role of bacterial biofilms in the pathogenesis of capsular contracture. REGISTRATION NUMBER: NCT01138891 (http://www.clinicaltrials.gov).

Postsurgical screening for psychosocial disorders in neurooncological patients.

BACKGROUND: The diagnosis of a brain tumor can cause severe psychosocial distress, which can have a variety of negative consequences on patients' physical and mental well-being. The detection of psychosocial distress in daily clinical routine is difficult and subsequent referral to mental health professionals is rare. The aim of this study was to determine the incidence of psychological disorders of patients early postoperatively and to investigate both the Hornheide Screening Instrument (HSI) and Distress Thermometer (DT) as screening tools in neurooncological practice. METHODS: One hundred and thirty-four patients with brain tumors of different histology were postoperatively evaluated by the Distress Thermometer and Hornheide Screening Instrument. Additionally, correlation to gender, age, localization of the tumor, Karnofsky performance score and tumor entity were analyzed. RESULTS: After initial surgery 36 patients (26.9 %) showed pathologic results in the HSI and 50 patients (36.7 %) were severely distressed (DT Score≥6). Women had the highest rate of psychological disorders, followed by patients suffering from gliomas and meningiomas. Further highlighting the results of both tests, over 80 % of those patients who scored pathologically in both tests were in need of professional psychiatric help due to depression. CONCLUSION: Both the DT and HSI are suitable instruments for identifying patients in psychological distress after brain tumor surgery in neurooncological routine. Our results confirm that nearly one third of patients are unable to overcome the difficulties facing the diagnosis of a brain tumor in this early situation and should be supported by mental health professionals.

Induction and abrogation of unresponsiveness in nude mouse cells.

Nude mice were injected with antigen and T cells at different times to induce unresponsiveness to SRBC. Spleen cells derived from these mice were tested in vitro for the capability to produce antibody-forming cells against sheep erythrocytes in the presence of a T-cell-replacing factor. It was found that priming with antigen alone did not result in paralysis but a later injection of thymus-derived lymphocytes together with antigen results in unresponsiveness of these cells in vitro, provided there was an interval of several days between the in vivo administration of thymus lymphocytes and the explantations of cells to in vitro cultures.

Color Doppler ultrasound and computed tomographic angiography for perforator mapping in DIEP flap breast reconstruction revisited: A cohort study.

INTRODUCTION: Preoperative imaging by Computed Tomographic Angiography (CTA) has been promoted a gold standard tool for perforator mapping in abdominally based microsurgical breast reconstruction, while Color Doppler Ultrasound (CDU) has lost its popularity. As the CTA X-ray exposure might have long-term consequences for patients, CDU has regained importance for preoperative workup in our center. Our aim was to revisit the role of CDU by comparing the reliability of CDU and CTA in predicting intraoperative perforator selection. MATERIALS AND METHODS: We performed a retrospective chart review study of patients who underwent microsurgical breast reconstructions with DIEP flaps at our institution. Both CTA and CDU were performed prior to the surgery, and both imaging entities were thoroughly examined by the surgical team. Perforator identification, number, size, and location were assessed and correlated with CTA and CDU data and with intraoperative findings. RESULTS: We identified 98 patients who received 125 DIEP flap surgeries. A significantly stronger correlation was found between CDU and intraoperative findings of perforator detection and size (p<0.0001) and selection (r = 0.9987, CI 0.9981-0.9991, p < 0.0001 and r = 0.01, CI -0.18-0.2, p = 0.91, respectively), when compared with CTA data. If none of the preoperative imaging studies matched intraoperative perforator selection, an association with a higher incidence of flap loss (Odds ratio 4.483, CI 0.5068-39.65, p = 0.2171) was found. CONCLUSIONS: Our data suggests that CDU might regain relevance as a safe and reliable preoperative imaging study, without the risk and potential consequences of X-ray exposure. Preoperative imaging tools like CDU and CTA should be considered part of the gold standard in abdominally based free flap breast reconstruction.

MyoRobot 2.0: An advanced biomechatronics platform for automated, environmentally controlled skeletal muscle single fiber biomechanics assessment employing inbuilt real-time optical imaging.

We present an enhanced version of our previously engineered MyoRobot system for reliable, versatile and automated investigations of skeletal muscle or linear polymer material (bio)mechanics. That previous version already replaced strenuous manual protocols to characterize muscle biomechanics properties and offered automated data analysis. Here, the system was further improved for precise control over experimental temperature and muscle single fiber sarcomere length. Moreover, it also now features the calculation of fiber cross-sectional area via on-the-fly optical diameter measurements using custom-engineered microscope optics. With this optical systems integration, the MyoRobot 2.0 allows to tailor a wealth of recordings for relevant physiological parameters to be sequentially executed in living single myofibers. Research questions include assessing temperature-dependent performance of active or passive biomechanics, or automated control over length-tension or length-velocity relations. The automatically obtained passive stress-strain relationships and elasticity modules are important parameters in (bio)material science. From the plethora of possible applications, we validated the improved MyoRobot 2.0 by assessing temperature-dependent myofibrillar Ca2+ sensitivity, passive axial compliance and Young's modulus. We report a Ca2+ desensitization and a narrowed dynamic range at higher temperatures in murine M. extensor digitorum longus single fibers. In addition, an increased axial mechanical compliance in single muscle fibers with Young's moduli between 40 - 60 kPa was found, compatible with reported physiological ranges. These applications demonstrate the robustness of our MyoRobot 2.0 for facilitated single muscle fiber biomechanics assessment.

A low percentage of autologous serum can replace bovine serum to engineer human nasal cartilage.

For the generation of cell-based therapeutic products, it would be preferable to avoid the use of animal-derived components. Our study thus aimed at investigating the possibility to replace foetal bovine serum (FBS) with autologous serum (AS) for the engineering of cartilage grafts using expanded human nasal chondrocytes (HNC). HNC isolated from 7 donors were expanded in medium containing 10% FBS or AS at different concentrations (2%, 5% and 10%) and cultured in pellets using serum-free medium or in Hyaff(R)-11 meshes using medium containing FBS or AS. Tissue forming capacity was assessed histologically (Safranin O), immunohistochemically (type II collagen) and biochemically (glycosaminoglycans -GAG- and DNA). Differences among experimental groups were assessed by Mann Whitney tests. HNC expanded under the different serum conditions proliferated at comparable rates and generated cartilaginous pellets with similar histological appearance and amounts of GAG. Tissues generated by HNC from different donors cultured in Hyaff(R)-11 had variable quality, but the accumulated GAG amounts were comparable among the different serum conditions. Staining intensity for collagen type II was consistent with GAG deposition. Among the different serum conditions tested, the use of 2% AS resulted in the lowest variability in the GAG contents of generated tissues. In conclusion, a low percentage of AS can replace FBS both during the expansion and differentiation of HNC and reduce the variability in the quality of the resulting engineered cartilage tissues.

The MyoRobot: A novel automated biomechatronics system to assess voltage/Ca2+ biosensors and active/passive biomechanics in muscle and biomaterials.

We engineered an automated biomechatronics system, MyoRobot, for robust objective and versatile assessment of muscle or polymer materials (bio-)mechanics. It covers multiple levels of muscle biosensor assessment, e.g. membrane voltage or contractile apparatus Ca2+ ion responses (force resolution 1µN, 0-10mN for the given sensor; [Ca2+] range ~ 100nM-25µM). It replaces previously tedious manual protocols to obtain exhaustive information on active/passive biomechanical properties across various morphological tissue levels. Deciphering mechanisms of muscle weakness requires sophisticated force protocols, dissecting contributions from altered Ca2+ homeostasis, electro-chemical, chemico-mechanical biosensors or visco-elastic components. From whole organ to single fibre levels, experimental demands and hardware requirements increase, limiting biomechanics research potential, as reflected by only few commercial biomechatronics systems that can address resolution, experimental versatility and mostly, automation of force recordings. Our MyoRobot combines optical force transducer technology with high precision 3D actuation (e.g. voice coil, 1µm encoder resolution; stepper motors, 4µm feed motion), and customized control software, enabling modular experimentation packages and automated data pre-analysis. In small bundles and single muscle fibres, we demonstrate automated recordings of (i) caffeine-induced-, (ii) electrical field stimulation (EFS)-induced force, (iii) pCa-force, (iv) slack-tests and (v) passive length-tension curves. The system easily reproduces results from manual systems (two times larger stiffness in slow over fast muscle) and provides novel insights into unloaded shortening velocities (declining with increasing slack lengths). The MyoRobot enables automated complex biomechanics assessment in muscle research. Applications also extend to material sciences, exemplarily shown here for spider silk and collagen biopolymers.

Adhesion Pad Formation and the Involvement of Cutinase and Esterases in the Attachment of Uredospores to the Host Cuticle.

We have investigated the basis of adhesion of uredospores of the obligately parasitic rust fungus Uromyces viciae-fabae to leaves of its broad bean host. Upon contact with an aqueous environment, spores form a structure that we have termed an adhesion pad. The adhesion pad is formed by both living and autoclaved spores, but only adhesion pads formed by living spores adhered to the cuticle of leaves of the host plant. Treatment of living spores with the serine-esterase inhibitor diisopropyl fluorophosphate prevented the adhesion of the pad to the leaf surface, suggesting a functional role for esterase or cutinase in the process of adhesion. A cutinase and two nonspecific serine-esterases were found to be localized on the surface of spores. These enzymes were released rapidly from the spore surface upon contact with an aqueous environment. The addition of the cutinase and the nonspecific esterases to autoclaved spores restored their ability to adhere to the host cuticle. Thus, whereas pad formation appears to be a passive response to the aqueous environment, the actual adhesion of pads to the host cuticle appears to depend on the cutinase and esterases associated with the spore surface. These results suggest a new role for cutinases and serine-esterases in the fungal infection process.

Evidence for free and metabolically stable p53 protein in nuclear subfractions of simian virus 40-transformed cells.

To determine functional subcellular loci of p53, a cellular protein associated with cellular transformation, we analyzed the nucleoplasmic, chromatin, and nuclear matrix fractions from normal mouse 3T3 cells, from methylcholanthren-transformed mouse (MethA) cells, and from various simian virus 40 (SV40)-transformed cells for the presence of p53. In 3T3 and MethA cells, p53 was present in all nuclear subfractions, suggesting an association of p53 with different structural components of the nucleus. In 3T3 cells, p53 was rapidly turned over, whereas in MethA cells, p53 was metabolically stable. In SV40-transformed cells, p53 complexed to large tumor antigen (large T) was found in the nucleoplasmic and nuclear matrix fractions, as described previously (M. Staufenbiel and W. Deppert, Cell 33:173-181, 1983). In addition, however, metabolically stable p53 not complexed to large T (free p53) was also found in the chromatin and nuclear matrix fractions of these cells. This free p53 did not arise by dissociation of large T-p53 complexes, suggesting that stabilization of p53 in SV40-transformed cells can also occur by means other than formation of a complex with large T.

Modulation of p53 protein expression during cellular transformation with simian virus 40.

We analyzed the relation of metabolic stabilization of the p53 protein during cellular transformation by simian virus 40 (SV40) to (i) expression of the transformed phenotype and (ii) expression of the large tumor antigen (large T). Analysis of SV40-tsA28-mutant-transformed rat cells (tsA28.3 cells) showed that both p53 complexed to large T and free p53 (W. Deppert and M. Haug, Mol. Cell. Biol. 6:2233-2240, 1986) were metabolically stable when the cells were cultured at 32 degrees C and expressed large T and the transformed phenotype. At the nonpermissive temperature (39 degrees C), large-T expression is shut off in these cells and they revert to the normal phenotype. In such cells, p53 was metabolically unstable, like p53 in untransformed cells. To determine whether metabolic stabilization of p53 is directly controlled by large T, we next analyzed the metabolic stability of complexed and free p53 in SV40 abortively infected normal BALB/c mouse 3T3 cells. We found that neither p53 in complex with large T nor free p53 was metabolically stable. However, both forms of p53 were stabilized in SV40-transformed cells which had been developed in parallel from SV40 abortively infected cultures. Our results indicate that neither formation of a complex of p53 with large T nor large-T expression as such is sufficient for a significant metabolic stabilization of p53. Therefore, we suggest that metabolic stabilization of p53 during cellular transformation with SV40 is mediated by a cellular process and probably is the consequence of the large-T-induced transformed phenotype.

Standardization of oncoplastic breast conserving surgery.

The emphasis on esthetic outcomes and quality of life after breast cancer surgery has motivated surgeons to develop oncoplastic breast conserving surgery (OPS). Training programs are still rare in most countries, and there is little standardization, which challenges the scientific evaluation of the techniques. The present article attempts to standardize OPS nomenclature, indications, and reconstruction choice selection embedded in a thorough review of the literature. We propose four breast conserving surgery (BCS) categories: Conventional tumorectomy, oncoplastic mastopexy, oncoplastic tumorectomy and oncoplastic reduction mammoplasty. The main volume displacement techniques are glandular re-approximation, use of tailored glandular or dermoglandular flaps and nipple-areola complex pedicles. We developed an indication algorithm based on the size and shape of the breast as well as the size and location of the tumor. A reconstruction algorithm suggests a selection of suitable tailored flaps and pedicles based on tumor location and vascular supply of the breast. The application of these algorithms results in known and novel OPS techniques, which are presented here with long-term results. We designed the algorithms to help tailor every operation to the individual patient in a standardized manner, since OPS is now on the rise, more than two decades after the publication of the first techniques. A rapidly increasing body of observational evidence suggests comparable rates of local recurrence between OPS and conventional BCS. Importantly, the rates of clear resection margins are in favor of OPS despite extended indications to larger tumors. Finally, OPS optimizes patient satisfaction by improving esthetic outcomes after BCS.

Low osmolality and shear stress during liposuction impair cell viability in autologous fat grafting.

BACKGROUND: Liposuction and subsequent autologous fat grafting have become essential techniques for fat augmentation in plastic surgery. However, standard harvesting techniques that ensure the survival of adipocytes and stromal vascular fraction (SVF) cells and thus preserve the transplanted fat volume are lacking. In particular, the effect of different parameters of the tumescent solution has not been studied in this context. We hypothesized that the osmolality of the tumescent solution could have a significant effect on the survival of adipocytes and SVF cells. METHODS: We developed two distinct in vitro models based on freshly harvested excision fat from patients undergoing surgical treatment. First, we investigated the effect of osmolality by incubating excision fat in different tumescent solutions and analyzed the total cell survival and the differentiation potential of SVF cells. Vital whole-mount staining, isolation yield of SVF cells, clonogenicity, and osteogenic and adipogenic differentiation capacities were analyzed. Second, we addressed the additional effect of mechanical stress by simulating a liposuction on pieces of excision fat after incubation with the tumescent solutions. RESULTS: Osmolality of the tumescent solution by itself did not have a significant effect on adipocyte and SVF viability or SVF differentiation. However, when osmolality was combined with liposuction, a significant trend toward lower viability and more lipid droplets with lower osmolality was observed. Especially, SVF viability was significantly lower after liposuction with a hypotonic (150 mOsm/kg) solution. CONCLUSION: This study demonstrates the considerable effect of osmolality during liposuction and may lead to the development of "cell-protective" tumescent solutions.

CXCR1 Regulates Pulmonary Anti-Pseudomonas Host Defense.

Pseudomonas aeruginosa is a key opportunistic pathogen causing disease in cystic fibrosis (CF) and other lung diseases such as chronic obstructive pulmonary disease (COPD). However, the pulmonary host defense mechanisms regulating anti-P. aeruginosa immunity remain incompletely understood. Here we demonstrate, by studying an airway P. aeruginosa infection model, in vivo bioluminescence imaging, neutrophil effector responses and human airway samples, that the chemokine receptor CXCR1 regulates pulmonary host defense against P. aeruginosa. Mechanistically, CXCR1 regulates anti-Pseudomonas neutrophil responses through modulation of reactive oxygen species and interference with Toll-like receptor 5 expression. These studies define CXCR1 as a novel, noncanonical chemokine receptor that regulates pulmonary anti-Pseudomonas host defense with broad implications for CF, COPD and other infectious lung diseases.

Ranitidine pharmacokinetics and adverse central nervous system reactions.

BACKGROUND: Treatment with histamine2-receptor antagonists has been associated with adverse central nervous system reactions (CNS-ADRs). Previous studies of cimetidine have shown an association between CNS-ADRs and high cimetidine drug levels. While case reports of ranitidine CNS-ADRs have appeared, we wanted to study a series of patients, some of whom were critically ill, for the presence of CNS-ADRs and to correlate these with ranitidine pharmacokinetics. METHODS: A prospective, observational, open study included 163 consecutive patients, of whom 41 met entry criteria. A nonlinear least-squares regression analysis was used to establish a ranitidine pharmacokinetic dosing model. Ranitidine levels were determined by a high-performance liquid chromatographic assay. Individual ranitidine pharmacokinetics were determined by means of a bayesian model. Observations on 13 possible CNS-ADRs were recorded. The CNS-ADRs were evaluated by the Naranjo rating system. RESULTS: Ranitidine-associated CNS-ADRs, particularly lethargy, confusion, somnolence, and disorientation, occurred more frequently in patients with renal function impairment, and these were associated with higher peak concentrations, average plasma concentrations, and area under the curve. CONCLUSIONS: Ranitidine, when given in conventional doses, can cause CNS-ADRs, particularly in older patients who have substantial renal function impairment. These CNS-ADRs occur as a consequence of altered ranitidine disposition. Ranitidine doses should be reduced when renal function impairment is present, and patients should be carefully observed for CNS-ADRs.