Cryosectioning-enabled super-resolution microscopy for studying nuclear architecture at the single protein level

DNA-PAINT combined with total Internal Reflection Fluorescence (TIRF) microscopy enables the highest localization precisions, down to single nanometers in thin biological samples, due to TIRF's unique method for optical sectioning and attaining high contrast. However, most cellular targets elude the accessible TIRF range close to the cover glass and thus require alternative imaging conditions, affecting resolution and image quality. Here, we address this limitation by applying ultrathin physical cryosectioning in combination with DNA-PAINT. With "tomographic & kinetically-enhanced" DNA-PAINT (tokPAINT), we demonstrate the imaging of nuclear proteins with sub-3 nanometer localization precision, advancing the quantitative study of nuclear organization within fixed cells and mouse tissues at the level of single antibodies. We believe that ultrathin sectioning combined with the versatility and multiplexing capabilities of DNA-PAINT will be a powerful addition to the toolbox of quantitative DNA-based super-resolution microscopy in intracellular structural analyses of proteins, RNA and DNA in situ.

PRECOGx: exploring GPCR signaling mechanisms with deep protein representations

In this study we show that protein language models can encode structural and functional information of GPCR sequences that can be used to predict their signaling and functional repertoire. We used the ESM1b protein embeddings as features and the binding information known from publicly available studies to develop PRECOGx, a machine learning predictor to explore GPCR interactions with G protein and β-arrestin, which we made available through a new webserver (https://precogx.bioinfolab.sns.it/). PRECOGx outperformed its predecessor (e.g. PRECOG) in predicting GPCR-transducer couplings, being also able to consider all GPCR classes. The webserver also provides new functionalities, such as the projection of input sequences on a low-dimensional space describing essential features of the human GPCRome, which is used as a reference to track GPCR variants. Additionally, it allows inspection of the sequence and structural determinants responsible for coupling via the analysis of the most important attention maps used by the models as well as through predicted intramolecular contacts. We demonstrate applications of PRECOGx by predicting the impact of disease variants (ClinVar) and alternative splice forms from healthy tissues (GTEX) of human GPCRs, revealing the power to dissect system biasing mechanisms in both health and disease.

Parental evaluation of a telemonitoring service for children with Type 1 Diabetes

Introduction In the past years, we developed a telemonitoring service for young patients affected by Type 1 Diabetes. The service provides data to the clinical staff and offers an important tool to the parents, that are able to oversee in real time their children. The aim of this work was to analyze the parents' perceived usefulness of the service. Methods The service was tested by the parents of 31 children enrolled in a seven-day clinical trial during a summer camp. To study the parents' perception we proposed and analyzed two questionnaires. A baseline questionnaire focused on the daily management and implications of their children's diabetes, while a post-study one measured the perceived benefits of telemonitoring. Questionnaires also included free text comment spaces. Results Analysis of the baseline questionnaires underlined the parents' suffering and fatigue: 51% of total responses showed a negative tendency and the mean value of the perceived quality of life was 64.13 in a 0-100 scale. In the post-study questionnaires about half of the parents believed in a possible improvement adopting telemonitoring. Moreover, the foreseen improvement in quality of life was significant, increasing from 64.13 to 78.39 ( p-value = 0.0001). The analysis of free text comments highlighted an improvement in mood, and parents' commitment was also proved by their willingness to pay for the service (median = 200 euro/year). Discussion A high number of parents appreciated the telemonitoring service and were confident that it could improve communication with physicians as well as the family's own peace of mind.

Psychological outcomes of evening and night closed-loop insulin delivery under free living conditions in people with Type 1 diabetes: a 2-month randomized crossover trial

AIM

To assess the impact on fear of hypoglycaemia and treatment satisfaction with an artificial pancreas system used for 2 consecutive months, as well as participant acceptance of the artificial pancreas system.

METHODS

In a randomized crossover trial patient-related outcomes associated with an evening-and-night artificial pancreas and sensor-augmented pump therapy were compared. Both intervention periods lasted 8 weeks. The artificial pancreas acceptance questionnaire (range 0-90, higher scores better), Hypoglycaemia Fear Survey II (range 0-72, higher scores worse) and Diabetes Treatment Satisfaction Questionnaire (range 0-36, higher scores better) were completed by 32 participants. Semi-structured interviews were conducted after study completion in a subset of six participants. Outcomes were compared using a repeated-measures anova model or paired t-test when appropriate.

RESULTS

The total artificial pancreas acceptance questionnaire score at the end of the artificial pancreas period was 69.1 (sd 14.7; 95% CI 63.5, 74.7), indicating a positive attitude towards the artificial pancreas. No significant differences were found among the scores at baseline, end of sensor-augmented pump therapy period or end of the artificial pancreas period with regard to fear of hypoglycaemia [28.2 (sd 17.5), 23.5 (sd 16.6) and 23.5 (sd 16.7), respectively; P = 0.099] or diabetes treatment satisfaction [29.0 (sd 3.9), 28.2 (sd 5.2) and 28.0 (sd 7.1), respectively; P = 0.43]. Themes frequently mentioned in the interviews were 'positive effects at work', 'improved blood glucose', 'fewer worries about blood glucose', but also 'frequent alarms', 'technological issues' and 'demand for an all-in-one device'.

CONCLUSIONS

The psychological outcomes of artificial pancreas and sensor-augmented pump therapy were similar. Current artificial pancreas technology is promising but user concerns should be taken into account to ensure utility of these systems.

Multicenter outpatient dinner/overnight reduction of hypoglycemia and increased time of glucose in target with a wearable artificial pancreas using modular model predictive control in adults with type 1 diabetes

AIMS

To test in an outpatient setting the safety and efficacy of continuous subcutaneous insulin infusion (CSII) driven by a modular model predictive control (MMPC) algorithm informed by continuous glucose monitoring (CGM) measurement.

METHODS

13 patients affected by type 1 diabetes participated to a non-randomized outpatient 42-h experiment that included two evening meals and overnight periods (in short, dinner & night periods). CSII was patient-driven during dinner & night period 1 and MMPC-driven during dinner&night period 2. The study was conducted in hotels, where patients could move around freely. A CGM system (G4 Platinum; Dexcom Inc., San Diego, CA, USA) and insulin pump (AccuChek Combo; Roche Diagnostics, Mannheim, Germany) were connected wirelessly to a smartphone-based platform (DiAs, Diabetes Assistant; University of Virginia, Charlottesville, VA, USA) during both periods.

RESULTS

A significantly lower percentage of time spent with glucose levels <3.9 mmol/l was achieved in period 2 compared with period 1: 1.96 ± 4.56% vs 12.76 ± 15.84% (mean ± standard deviation, p < 0.01), together with a greater percentage of time spent in the 3.9-10 mmol/l target range: 83.56 ± 14.02% vs 62.43 ± 29.03% (p = 0.04). In addition, restricting the analysis to the overnight phases, a lower percentage of time spent with glucose levels <3.9 mmol/l (1.92 ± 4.89% vs 12.7 ± 19.75%; p = 0.03) was combined with a greater percentage of time spent in 3.9-10 mmol/l target range in period 2 compared with period 1 (92.16 ± 8.03% vs 63.97 ± 2.73%; p = 0.01). Average glucose levels were similar during both periods.

CONCLUSIONS

The results suggest that MMPC managed by a wearable system is safe and effective during evening meal and overnight. Its sustained use during this period is currently being tested in an ongoing randomized 2-month study.

Risk of perioperative seizures in patients undergoing craniotomy with intraoperative brain mapping

BACKGROUND

The identification of risk factors associated with perioperative seizures would be of great benefit to the anesthesiologist in managing brain tumor patients undergoing craniotomy with intraoperative brain mapping.

METHODS

A series of 316 supratentorial craniotomies for tumor resection, in which intraoperative brain mapping was used, were analyzed. From January 2005 to December 2010 the occurrence of intraoperative and immediate postoperative clinical seizures was prospectively recorded into a database. Demographic data, tumor characteristics, preoperative seizure control, intraoperative events and anesthetic management were evaluated as risk factors for intraoperative clinical seizures. Additionally, the association between intraoperative clinical seizures and immediate postoperative seizures was evaluated. In order to determine the best predictors of intraoperative and immediate postoperative clinical seizures, a multivariable analysis by logistic regression was performed.

RESULTS

Younger age, location of the tumor in the frontal and parietal lobe, brain mapping conducted under general anesthesia and non physiologic values of arterial carbon dioxide (PaCO2) during brain mapping were independent positive risk factors for the development of intraoperative clinical seizures. Location of tumor in the frontal lobe, antiepileptic polytherapy, intraoperative seizures requiring pharmacologic treatment during brain mapping, and blood on postoperative CT scan were independent positive risk factors for the development of immediate postoperative seizures.

CONCLUSION

Clinical seizures are common intraoperative and postoperative complications of supratentorial craniotomies with intraoperative brain mapping. The identification of those patients at higher risk of seizures may guide intraoperative and postoperative medical management.

Modular closed-loop control of diabetes

Modularity plays a key role in many engineering systems, allowing for plug-and-play integration of components, enhancing flexibility and adaptability, and facilitating standardization. In the control of diabetes, i.e., the so-called "artificial pancreas," modularity allows for the step-wise introduction of (and regulatory approval for) algorithmic components, starting with subsystems for assured patient safety and followed by higher layer components that serve to modify the patient's basal rate in real time. In this paper, we introduce a three-layer modular architecture for the control of diabetes, consisting in a sensor/pump interface module (IM), a continuous safety module (CSM), and a real-time control module (RTCM), which separates the functions of insulin recommendation (postmeal insulin for mitigating hyperglycemia) and safety (prevention of hypoglycemia). In addition, we provide details of instances of all three layers of the architecture: the APS© serving as the IM, the safety supervision module (SSM) serving as the CSM, and the range correction module (RCM) serving as the RTCM. We evaluate the performance of the integrated system via in silico preclinical trials, demonstrating 1) the ability of the SSM to reduce the incidence of hypoglycemia under nonideal operating conditions and 2) the ability of the RCM to reduce glycemic variability.

Awake neurosurgery: an update

Intraoperative brain mapping has the goal of aiding with maximal surgical resection of brain tumors while minimizing functional sequelae. Retrospective randomized studies on large populations have shown that this technique can optimize the surgical approach while reducing postoperative morbidity. During direct electrical stimulation of the language areas adjacent to the tumor, the patient should be collaborative and be able to speak to participate in language testing. Different anesthesiological protocols have been proposed to allow intraoperative brain mapping, which range from local anesthesia to conscious sedation or general anesthesia, with or without airway instrumentation. The most common intraoperative complications are seizure, respiratory depression, and patients' stress and discomfort. Since awake craniotomy carries both benefits and potential risks, the following factors are crucial in the management of patients: 1) careful selection of the patients and 2) communication between the anesthesiological and surgical teams. To date, there remains no consensus about the optimal anesthesiological regimen to use. Only prospective, multicentre randomized studies focused on evaluating the role of different anesthesiological techniques on intraoperative monitoring, postoperative deficits, and intraoperative complications can answer the question of which anesthesiological approach should be chosen when intraoperative brain mapping is requested.

R-plasmids in Salmonella isolates from sporadic cases of gastroenteritis

Five-hundred and twenty seven strains of Salmonella isolated from different patients admitted to hospitals in Rome from 1982 to 1985 were screened for their resistance to antimicrobial drugs. Sixty-one strains (11.6%) were found to be resistant to two or more antibiotics; the most frequent resistances were to sulfathiazole, streptomycin, tetracycline, chloramphenicol and ampicillin. Of the thirty-eight strains showing resistance to three or more antibiotics, 17 were able to transfer their resistance to E. coli K 12. The isolates were heterogeneous in plasmid population: only few strains harbored a sole plasmid, most harbored many plasmids ranging between 20 and 120 megadaltons in weight. Most strains were found to carry a conjugative plasmid of incompatibility group Inc H of 100-120 megadaltons and Inc I alpha of 60-70 megadaltons.

Penetration of penicillins into cardiac valves and auricles of patients undergoing open-heart surgery

Prophylactic use of antibiotics in open-heart surgery for insertion of prosthetic valves is common, because of the serious consequences of postoperative staphylococcal infections, most notably prosthetic valve endocarditis. To ensure effective antibiotic cover during surgery, the penetration of cloxacillin and benzylpenicillin into the heart muscle and valves was studied intraoperatively. Both antibiotics were given intravenously (respective initial doses 2 g and 6 g) at induction of anesthesia to ten patients undergoing replacement of aortic or mitral valve, and the same doses were repeated after 4 hours. Serial serum samples and tissue samples from the right atrial auricle and the excised heart valve were analyzed for antibiotic concentrations. The mean serum concentrations of cloxacillin were 204 +/- 93 mg/l 10 min after the initial dose and less than or equal to 26 mg/l 30 min before the second dose. The corresponding values for benzylpenicillin were 323 +/- 145 and 43 +/- 24 mg/l. The cloxacillin concentrations in the auricle just before the start of extracorporeal circulation ranged from 4.5 to 80 mg/kg and (later) in the excised heart valves they were 8.5 to 45 mg/kg. The benzylpenicillin range was 16 to 153 mg/kg in auricle and 13 to 87 mg/kg in valve tissue. The authors conclude that the employed doses of the penicillins are adequate cover against the staphylococci which may be implicated in postoperative infections.

Rectal bioavailability of bacampicillin hydrochloride in man as determined by reversed-phase liquid chromatography

The relative bioavailability of bacampicillin hydrochloride, a pro-drug of ampicillin, was compared after rectal and oral administration. Bacampicillin was administered rectally as a microenema . The oral formulation was an aqueous microcapsule suspension. They were given as single doses of 400 mg to 12 healthy volunteers after overnight fasting using a randomized cross-over design. Ampicillin and bacampicillin were determined in plasma and blood, respectively, using HPLC. Bacampicillin was rapidly absorbed from the rectum but to a much smaller degree compared to the oral dose. The median t-max was 0.5 and 0.75 h after the rectal and oral doses, respectively. The mean (SD) Cp-max was 1.2 (0.33) mg/l after rectal and 4.8 (0.98) mg/l after oral administration, respectively. Blood concentrations of bacampicillin were extremely low or undetectable with no indication of differences between the two modes of administration. The 95% confidence limits for the relative bioavailability of the microenema were 22.4-39.2 and 22.5-40.4% based on area under the plasma concentration time curve and urinary recovery, respectively. The rectal dose was followed by distress, diarrhea or pain, in 7 subjects. There were no adverse reactions after the oral dose. Bacampicillin was unaffected by beta-lactamases produced by intestinal bacteria.

Absorption of phenoxymethylpenicillin from mixtures and tablets in healthy volunteers

The absorption of the potassium, calcium and benzathine salts of phenoxymethylpenicillin, given as mixtures, was investigated in twelve healthy volunteers. The potassium salt gave the fastest and highest serum peak levels. Also the relative bioavailability of the potassium salt was greatest, as indicated by the areas under the serum concentration/time curves (AUC). In a second study with twelve other volunteers, the absorption of the mixtures and tablets of the potassium salt was studied. The peak serum levels and AUC were comparable after these preparations. The results in our two studies indicate that, from a pharmacokinetic point of view, the potassium salt of phenoxymethylpenicillin in mixtures should be preferred in clinical practice. It also appears that the absorption of phenoxymethylpenicillin from the tablets and mixtures of the potassium salt is comparable, giving the same relative bioavailability.

High dose phenoxymethylpenicillin for preventing endocarditis

Single oral doses of phenoxymethylpenicillin were administered to 12 healthy volunteers, and their serum, saliva, and urine phenoxymethylpenicillin concentrations were determined. At all dose levels (0.4, 1, 2 and 3 g) phenoxymethylpenicillin was rapidly absorbed usually giving peak serum concentrations after 0.75 h. The relationship between mean peak serum concentration and dose was nonlinear (p less than 0.001); between area under serum concentration vs. time curve (AUC) and dose, it did not deviate from linearity (NS). Very low penicillin concentrations were obtained in saliva and the changes in the normal microflora were minor. The urinary excretion during the 10 h period after drug administration was 37-43 % of the given doses. After the 3 g doses, 3 volunteers had loose stools.

Dose-related pharmacokinetics after oral administration of a new formulation of erythromycin base

1 Erythromycin concentrations in serum and urine were determined in 24 healthy male, fasting subjects after oral administration of 250, 500, or 1000 mg of erythromycin base (250 mg capsules containing enteric-coated pellets). The subjects also received a film-coated erythromycin stearate tablet (equivalent to 500 mg base). 2 The mean +/- s.d. maximal serum erythromycin concentrations were 1.9 +/- 0.8, 3.8 +/- 1.4, 6.5 +/- 2.9 and 2.9 +/- 1.7 mg/l for 250, 500, or 1000 mg base and 500 mg stearate, respectively. The serum peaks usually occurred after 2 h irrespective of dosage form given. 3 The mean +/- s.d. areas under the serum concentration v time curves (AUC0-infinity) were 4.5 +/- 1.7, 11.2 +/- 4.3, 27.2 +/- 10.6 and 7.5 +/- 3.4 mg l -1 . h after 250, 500, or 1000 mg base, and 500 mg stearate, respectively. 4 The urinary recoveries were 5.0, 6.7, 8.6% of the base doses given and 4.4% of the stearate dose given. 5 Dose-dependent excretion of erythromycin occurred. The increase in AUC was larger than multiples of the lowest base dose.

Pharmacokinetics of bacmecillinam and pivmecillinam in volunteers

The pharmacokinetics of bacmecillinam and pivmecillinam were studied in healthy fasting volunteers given tablets in a cross-over, randomized order. The mean (+/- SD) peak levels of plasma mecillinam were 1.43 +/- 0.34, 2.73 +/- 0.43, and 4.62 +/- 1.41 mg/l after bacmecillinam 100, 200, and 400 mg and 2.38 +/- 0.65 mg/l after pivmecillinam 400 mg. The corresponding areas under plasma Vs time curves (AUC) were 2.21 +/- 0.19, 3.99 +/- 0.63, and 7.74 +/- 1.38 mg . h. l-1 for bacmecillinam and 5.35 +/- 0.93 mg . h. l-1 for pivmecillinam. The elimination half-lives were 0.8-1.1 h for bacmecillinam and 0.7 h for pivmecillinam. The 12 h urinary recovery of unchanged mecillinam after the 400 mg doses was 41% for bacmecillinam and 30% for pivmecillinam. The 400 mg dose of bacmecillinam gave a significantly higher plasma peak (p less than 0.001), AUC (p less than 0.001) and urinary recovery (p less than 0.001) than did pivmecillinam 400 mg. The plasma peaks appeared earlier and the rate of absorption was higher after bacmecillinam than after pivmecillinam (p less than 0.05). In conclusion, bacmecillinam had a better bioavailability than pivmecillinam in the tablet formulations studied. The AUC increased linearly with increasing doses of bacmecillinam.

Pharmacokinetics of a new, microencapsulated erythromycin base after repeated oral doses

Pharmacokinetics of a new preparation of microencapsulated erythromycin base was studied in 16 healthy subjects. They received 250 mg base 6-hourly or 500 mg 12-hourly for 7 days. The mean maximal serum peaks (+/- SD) after morning doses on days 1, 2, 3, and 7 were 1.4 +/- 0.9, 3.2 +/- 1.1, 3.6 +/- 0.6, 3.5 +/- 1.2 mg/l after the 250-mg dose and 3.2 +/- 1.5, 3.7 +/- 2.1, 3.6 +/- 1.8, and 3.0 +/- 2.0 mg/l after the 500-mg dose. The mean 24-hour urine recoveries were 1.8 and 1.2%, the serum half-lives were (days 1-7) 1.4-2.1 h and 1.9-2.8 h for the 250-mg and 500-mg doses. The mean areas under the serum concentration curves (+/- SD) were 5.8 +/- 2.2, 11.9 +/- 2.2, and 15.3 +/- 5.1 mg . h . 1(-1) after 250 mg and 14.2 +/- 4.9, 16.4 +/- 7.6, and 14.3 +/- 9.0 mg . h . 1(-1) after 500 mg on days 1, 2, and 7. The inter- and intrasubject variability was larger after the 500-mg dose. The pharmacokinetic results indicate that both dosage alternatives are suitable and result in similar steady-state peak levels, but the initial dose should be 500 mg.

Bioavailability of bacampicillin and talampicillin, two oral prodrugs of ampicillin

A 200-mg amount of bacampicillin showed a significantly higher relative extent of bioavailability than did a 250-mg amount of talampicillin, possibly due to their different stability in the digestive juices.

Comparative in vivo activity of bacampicillin and amoxycillin

Bacampicillin is an orally well-absorbed pro-drug of ampicillin giving high in vivo levels of the latter. Its therapeutic activity was compared with that of amoxycillin in two experimental infection models in mice. The animals were infected with suspensions of Escherichia coli III and Haemophilus influenzae 22863 intraperitoneally and treated orally four hours afterwards with one of the two compounds. The antibacterial activity of the compounds was determined as CD50 values or by making viable counts in the blood and in organ homogenates of the animals. Ampicillin and amoxycillin had the same inhibitory but different bactericidal activity against the test strains. Both compounds appeared to have similar therapeutic activity and were found to cause a rapid decrease of the bacterial counts in the animals. Bacampicillin appeared to give a more rapid bactericidal activity than amoxycillin against the Haemophilus influenzae strain, whereas amoxycillin initially appeared more bactericidal against the Escherichia coli infection.

Development of sulphonamide-trimethoprim combinations for urinary tract infections. Part 3: Pharmacokinetic characterization of sulphadiazine and sulphamethoxazole given with trimethoprim

Plasma levels and renal excretion of sulphonamide and trimethoprim following oral administration of co-trimazine (140 mg sulphadiazine + 90 mg trimethoprim) and co-trimoxazole (800 mg sulphamethoxazole + 180 mg trimethoprim) were monitored in healthy volunteers after a single dose and in the steady state after 12-hourly dosage. The plasma levels of free, non-protein bound components after co-trimazine were approximately half those after co-trimoxazole and thus correlated with the doses given. Urine recovery of trimethoprim was better after co-trimazine (70%) than after co-trimoxazole (58%). Sixty-six percent of the sulphadiazine was recovered as unchanged, active sulphonamide in the urine compared with only 13% of the sulphamethoxazole. Consequently, the sulphonamide levels of sulphadiazine were 2.5 times those of sulphamethoxazole. With respect to plasma half-life after the first dose, sulphadiazine with 8.0 hours was closer to trimethoprim with a half-life of 8.8 hours after cotrimazine and 9.6 hours after co-trimoxazole than to the half-life of sulphamethoxazole which was 7.7 hours. The distribution volume of sulphadiazine was closer to that of trimethoprim than was that of sulphamethoxazole. On the basis of these characteristics, it has been concluded that sulphadiazine is more suitable for a fixed combination tablet with trimethoprim than sulphamethoxazole, particularly for the treatment of urinary tract infections. Some renal tubular reabsorption occurs with both unchanged sulphonamides but is more pronounced with sulphamethoxazole. The solubilities of the sulphonamides and their acetylated metabolites at acid urinary pH indicate that therapy with co-trimazine is at least as safe as with co-trimoxazole. With the former drug, the result of scrutiny for crystals after dosage until the steady state was negative, whereas crystals of acetylated sulphamethoxazole were detected and verified chemically in two of eight subjects.

Synergistic activity of co-trimazine and co-trimoxazole in the urine

Co-trimazine (sulphadiazine, 410 mg + trimethoprim, 90 mg) is a new drug combination developed especially for use in the treatment of urinary tract infections. In cross-over experiments in volunteers receiving daily doses of co-trimazine (2 X 500 mg and 1 X 1000 mg), co-trimoxazole (2X960 mg), or nitrofurantoin (3X50 mg), the degree of antibacterial activity of co-trimazine in the urine was at least as high as that of co-trimoxazole and much higher and more consistent than that of nitrofurantoin. In further cross-over experiments in volunteers receiving co-trimazine 2X1000 mg or co-trimoxazole 2X960 mg for four days no or only slight activity was found in the urine against a sulphonamide-resistant Group D streptococcus, but distinct synergistic activity between the components was found against four Escherichia coli strains sensitive to trimethoprim and sensitive or resistant to sulphonamides. Against three of the latter strains the degree of activity in the urine was higher after co-trimazine than after cotrimoxazole. The synergistic action of trimethoprim and sulphonamide in the urine appeared greater with the former than with the latter combination.

Effect of in vitro treatment with reducing drugs on structure and function of human secretory immunoglobulin A

Samples of unstimulated whole saliva from 15 healthy children with 0.5--6 mg/100 ml of secretory IgA and from 10 healthy adults with 4--18 mg/100 ml of secretory IgA were pooled and treated in vitro with dithiothreitol and alpha-mercaptopropionylglycine. The effect of these reducing drugs on the immunochemical properties of secretory IgA was evaluated. Dithiothreitol induced depolymerization of secretory IgA and splitting of the secretory piece from the IgA molecule; furthermore it strongly reduced the titer of secretory antibodies to Escherichia coli antigens. The drug alpha-mercaptopropionylglycine apparently did not affect either the polymeric structure of secretory IgA or the titer of secretory anti-E. coli antibodies; however it induced splitting of the secretory piece. On the whole it appers that drugs with reducing properties, currently employed for liquifying mucous secretions in clinical practice, should be carefully evaluated for possible depressive side-effects on local immunity.

Antibacterial activity of co-trimazine in vitro and in vivo

Co-trimazine is a new drug combination especially designed for the treatment of urinary tract infections. It consists of trimethoprim (90 mg) and sulphadiazine (410 mg). When combined in vitro, the components show high activity and a high frequency of synergy against urinary tract pathogens. After oral absorption sulphadiazine has a serum half-life similar to that of trimethoprim and is excreted in active form into the urine to a much higher degree than sulphamethoxazole. The ratio of the concentrations of trimethoprim and sulphadiazine in the urine following co-trimazine is favourable for a strong synergistic action between the compounds. In cross-over studies in volunteers receiving repeated daily doses of co-trimazine, either 500 mg twice daily or 1000 mg once daily, it was found that antibacterial activity in the urine was at least as high as that provided by co-trimoxazole (2 x 960 mg) and considerably higher and more uniform than that given by nitrofurantion (3 x 50 mg).

Comparative clinical pharmacology of bacampicillin and high oral doses of ampicillin

Ampicillin is often used in high oral doses due to its incomplete absorption. The objective of this study was to compare the bioavailability of bacampicillin, a new prodrug of ampicillin which is nearly completely absorbed, to that of high doses of oral ampicillin. Single oral doses of bacampicillin 400 mg or 800 mg and ampicillin 500 mg, 1 g, or 2 g were given to 12 male subjects according to a cross-over design after overnight fasting. The median time after administration till the peak serum level was 0.75 and 1.0 hour with bacampicillin 400 mg and 800 mg respectively, as compared to 1.5, 2.0 and 1.5 hours for the ampicillin doses. The mean of the individual peak serum level after bacampicillin 400 mg, was 7.7 mg/l, which is higher than that after ampicillin 500 mg, 5.2 mg/l, and about the same as that after ampicillin 1 g, 7.6 mg/l. A slightly higher mean peak level was seen after bacampicillin 800 mg, 12.2 mg/l, as compared to ampicillin 2 g, 10.5 mg/l. The absorption rate was highest with bacampicillin, for which 90% of the absorption had occurred 1 hour after administration as compared to 2.5 hours after administration of ampicillin. The relative bioavailability was about 2--3 times higher after bacampicillin as compared to ampicillin. The data imply dose-dependent absorption of oral ampicillin in high doses as there seems to be a less than proportional increase in AUC. The urinary recovery after bacampicillin was 68--75% as compared to 25--41% after ampicillin. Higher doses gave a lower percentage recovery and this phenomenon was more pronounced with ampicillin.

Pharmacokinetics of bacampicillin compared with those of ampicillin, pivampicillin, and amoxycillin

Bacampicillin, a new oral prodrug which in vivo is rapidly transformed to ampicillin, was compared with ampicillin, pivampicillin, and amoxycillin in a randomized cross-over study on 11 healthy volunteers. All drugs were given in oral doses equimolar to 400 mg of bacampicillin (800 mumol). The mean of the individual peak concentrations in serum was 8.3 mug/ml for bacampicillin, 7.1 mug/ml for pivampicillin, 7.7 mug/ml for amoxycillin, and 3.7 mug/ml for ampicillin. Furthermore, bacampicillin had a higher absorption rate than all the other drugs, although there were statistically significant differences only versus ampicillin. The peak serum levels of the individual subjects were more dispersed with ampicillin and amoxycillin, suggesting a more uniform absorption of bacampicillin and pivampicillin. The relative bioavailability of bacampicillin and pivampicillin was comparable, whereas ampicillin was only 2/3 that of the others.

Bacampicillin: a new orally well-absorbed derivative of ampicillin

Bacampicillin (proposed international nonproprietary name), 1'-ethoxycarbonyloxyethyl 6-(d-alpha-aminophenylacetamido)penicillanate, is a new orally well-absorbed penicillin, highly active in vivo due to rapid transformation into ampicillin. The compound is stable in vitro at gastric pH and hydrolyzed slowly to ampicillin at neutral pH but very rapidly in the presence of biological fluids, e.g., tissue homogenates or serum. In vivo the transformation into ampicillin is so rapid that no unchanged compound could be detected in the blood after oral administration of bacampicillin to rats, dogs, and humans. On oral administration to mice, rats, and dogs, bacampicillin was found to be better absorbed than ampicillin, giving higher and earlier peak blood levels of ampicillin. The bioavailability of bacampicillin in rats and dogs was three to four times higher than that of an equimolar amount of ampicillin. On oral administration to rats, bacampicillin was found to give higher levels of ampicillin in organs such as the kidney, liver, and spleen than ampicillin itself. In "tissue cages" in rats, higher transudate levels of antibiotic were found after oral administration of bacampicillin than after ampicillin. On oral treatment of experimentally infected mice, bacampicillin was found to be more active than ampicillin.