Purification and sequencing of the active site tryptic peptide from penicillin-binding protein 5 from the dacA mutant strain of Escherichia coli (TMRL 1222)

The localization of the active site of penicillin-binding protein 5 from the dacA mutant of Escherichia coli strain TMRL 1222 has been determined. The protein was purified to homogeneity and labeled with [14C] penicillin G. The labeled protein was digested with trypsin, and the active site tryptic peptide was purified by a combination of gel filtration and high-pressure liquid chromatography. Sequencing of the purified [14C]penicilloyl peptide yielded the sequence Arg-Asp-Pro-Ala-Ser-Leu-Thr-Lys, which corresponds to residues 40-47 of the gene sequence (Broome-Smith, J., Edelman, A., and Spratt, B. G. (1983) in The Target of Penicillin (Hakenbeck, R., Holtje, J.-V., and Labischinski, H., eds) pp. 403-408, Walter de Gruyter, Berlin). The catalytic amino acid residue that forms a covalent bond with penicillin was identified by treating the purified [14C]penicilloyl peptide with a mixture of proteases and then separating the radioactive products using high-pressure liquid chromatography. Analysis of the radioactive peaks by amino acid analysis confirmed that it is the serine residue that reacts with the beta-lactam ring of penicillin.

[Fat utilization in newborn infants with and without heparin administration. Comparative study with the 13C-triolein breath test]

The elimination of parenterally administered lipids from the bloodstream of premature infants can be accelerated by activation of the lipoprotein-lipase using heparin. We have no evidence that the free fatty acids increasing under enhanced lipolytical activity are utilized for energy production. For this reason, the oxidation rates of intravenously administered lipids in premature infants are examined both with and without heparin. Triolein marked with 13C and processed in soybean oil is administered intravenously at a dosage of 10 mg/kg. 13CO2 results from fatty acid oxidation and is exhaled through the lungs, whereafter it is collected in separate breath samples over a period of 6 hours and determined by mass spectrometry. The examination was performed in 5 premature infants, first without heparin, then after heparin injection (10 U/kg). The extent of 13CO2 exhalation was not significantly influenced by heparin. Without heparin supply we measured a fatty acid oxidation of 32.0 +/- 2.57% which was the same (31.6 +/- 2.34%) after heparin injection. Single intravenous administration of 10 U heparin/kg does not cause increased fatty acid oxidation in premature infants.

The affinity of imipenem (N-formimidoylthienamycin) for the penicillin-binding proteins of Staphylococcus aureus--binding and release

Penicillin-binding proteins 1, 2 and 3 in Staphylococcus aureus were found to possess common properties. All have very strong affinities for both benzylpenicillin and imipenem (N-formimidoylthienamycin), and all have an activity which releases bound imipenem, but not bound benzylpenicillin. Lower molecular weight penicillin-binding protein 4, which has a rather weak affinity for benzylpenicillin and also weak penicillinase activity showed an extraordinarily high affinity for imipenem but no antibiotic-releasing activity.

Measurement of fatty acid oxidation in premature newborn infants with the 13C-triolein breath test

The 13C-triolein breath test is a method giving evidence of extent and rate of fatty acid oxidation in newborn infants on parenteral nutrition. The test has the special advantage of being non-invasive. Triolein labeled with the stable carbon isotope 13C and emulsified in soybean-oil is used as a tracer. 10 mg of 13C triolein per kg body weight are administered intravenously. The 13CO2 resulting from the fatty acid oxidation is analysed in expired breath by ratio-mass-spectrometry. The calculated 13C elimination is representative of the rate of fatty acid oxidation during the examination period. First studies on 15 premature infants have shown that an average of 27.0 +/- 1.8% of the dose administered is oxidized within 4 h. The present results suggest that the oxidation rate may be related to the maturity of the prematurely born infants.

Lipid infusion in premature infants suffering from sepsis

In as much as possible side effects attributing to insufficient fat clearance with hyperlipemia, parenteral lipid administration to septic premature infants is controversial. In this study serum triglyceride and free fatty acid concentrations of nine low birth weight infants with septicemia and 21 low birth weight infants without septicemia were measured. Acidosis, hypoxia, hyperglycemia, and cardiovascular insufficiency were treated before parenteral lipid infusion was started. There was no occurrence of septic shock. In the course of fat infusion with 3 g/kg body weight per day in low birth weight infants without systemic infection we only found triglyceride concentrations of 1.15 mmol/liter and free fatty acid levels of 1.05 mmol/liter. Premature infants with septicemia showed, under fat application of 2 g/kg body weight per day, mean triglyceride levels of 1.67 mmol/liter and free fatty acid values of 1.94 mmol/liter. The highest concentrations occurred at 3 g fat/kg body weight per day with triglycerides of 2.02 mmol/liter and free fatty acids of 2.06 mmol/liter. They indicate a reduced clearance and support earlier findings of reduced utilization of infused fat in premature infants with septicemia. Triglyceride concentrations more than 1.7 mmol/liter probably induce an increase of phagocytosis of the fat particles with the effect of a partial block of the reticuloendothelial system and an impairment of pulmonary diffusion capacity. Therefore, we suggest dosages no higher than 2 g fat/kg body weight per day to low birth weight infants and we advise to check the triglycerides daily. Hypertriglyceridemia implicates an immediate reduction or total interruption of the lipid infusion until normal triglyceride values are regained.

Staphylococcus aureus and Micrococcus luteus peptidoglycan transglycosylases that are not penicillin-binding proteins

Major peptidoglycan transglycosylase activities, which synthesize uncross-linked peptidoglycan from lipid-linked precursors, were solubilized from the membranes of Staphylococcus aureus and Micrococcus luteus and were partially purified. The transglycosylase activities were separated from penicillin-binding proteins by solubilization and by purification steps. Therefore, we concluded that these activities were not activities of the penicillin-binding proteins, which are the presumptive peptidoglycan transpeptidases in these gram-positive cocci. Unlike Escherichia coli, in which the network structure of peptidoglycan is synthesized by multiple two-headed penicillin-binding proteins with both transpeptidase and transglycosylase activities, these gram-positive cocci have cell wall peptidoglycan which seems to be synthesized by penicillin-binding protein transpeptidases and a separate transglycosylase.

Adducted thumb syndrome. Report of a new case and a diagnostic approach

We report on a female newborn baby with a "myopathic" stiff face, open mouth, high-arched palate, microgenia, generalized muscular hypotonia, limited extension of elbows, wrists and knees, flexed adducted thumbs, velopharyngeal insufficiency, and hypertrichosis. Death occurred at 3 months due to respiratory insufficiency. Muscular biopsy revealed myopathic abnormalities.

Fat elimination in parenterally fed low birth weight infants during the first two weeks of life

Eighteen low birth weight infants (27-34 wk gestation) were given supplementary parenteral nutrition via peripheral veins of a maximal dose of 8.5 g glucose, 2.5 g amino acids (Aminovenös päd 10%) and 2 g soybean oil egg lecithin emulsion (Intralipid 10%) kg body weight/24 hr. The fat emulsion was infused continuously at a rate of 0.084 g/kg body weight/hr. The elimination of Intralipid from the blood stream was controlled by enzymatic determination of serum triglyceride concentrations, and the fatty acid pattern of the serum lipids was determined by gas chromatography. The serum triglyceride concentrations were 0.60 +/- 0.16 mmol/liter on the 1st day, increased to 0.96 +/- 0.29 mmol/liter up to the 5th day, and approached a level around 0.90 mmol/liter in the further course. No hypertriglyceridemia was noted. The fatty acid pattern of the serum lipids showed a linoleic acid fraction of 8.1 +/- 4.0% in the beginning, which was followed by a continuous increase up to 27.8 +/- 4.8% on the 7th day. No significant changes were noticed thereafter. The levels were within the normal limits as found in 2-wk-old enterally fed preterm infants of comparative maturity (25.6 +/- 3.4%). We conclude that the preterm infants can eliminate Intralipid from the blood stream if maximal dosage and infusion rate, as described above, are applied.

[Current status of parenteral feeding with fat infusions. Clinical experiences with premature and newborn infants]

By administration of fat emulsion a well-balanced parenteral nutrition concerning calories is possible in newborn infants. Investigations with great amounts of fat during and after a short-time infusion have shown that the maximal fat clearance of very-low-birth-weight and small-for-gestational-age newborn infants is limited. Heparin can improve the lipid clearance and reduce hyperlipaemia occurring under lipid application. The fat oxidation is not affected by heparinization. Extent and velocity of the fatty acid utilization can be judged by the 13C-triolein breath test. Under the clinical conditions of a continuous long-term infusion with 2 g fat/kg BW/day a complete fat clearance is observed in low-birth-weight infants with respiratory distress syndrome and septicaemia and small-for-gestational-age newborn infants. The determination of serum triglycerides is considered to be a sufficient control of fat clearance in respect to clinical concerns. The fat emulsion is continuously applied for 24 h and is being increased stepwise up to a dosage of 2-3 g/kg BW/day. Before starting parenteral nutrition, acidosis, hypoxaemia, hyperglycaemia and insufficient circulation must have been treated. Contraindications to this are shock, disturbances of blood coagulation and of fat metabolism. Complications are avoided by using an adapted and standardized nutritional programme under sufficient clinical and laboratory control.

[Intravenous administration of lipids in parenteral nutrition of preterm and newborn infants]

Total or supplementary parenteral nutrition is a main part of therapy of sick preterm and newborn infants. It becomes necessary when oral feeding is not or not completely possible. Administration of lipids for parenteral feeding has the following advantages: 1. well-balanced nutrition concerning calories, 2. high energy density in low volume, 3. blood isotonicity, 4. infusion into peripheral veins is possible, 5. lack of essential fatty acids is avoided. Before starting parenteral nutrition, acidosis, hypoxaemia, hyperglycaemia and insufficient circulation must have been treated. The fat supply is being increased step-wise up to a dosage of 2--3 g/kg bwt/day whilst controlling the serum triglyceride concentration. The fat emulsion is continuously applied for 24 h. Contraindications to this are shock, disturbances of blood coagulation and of fat metabolism. Complications are avoided by an appropriate and standardized nutritional programme and sufficient clinical and laboratory control.

Unilateral spondylolysis

Five vertebrae with unilateral spondylolysis are presented. The associated asymmetry of the posterior elements supports the concept of a localised form of growth deficiency. The defect is difficult to demonstrate radiologically, and is perhaps present more frequently than is recognised. It should be suspected clinically from asymmetry of the neural arch and from unilateral wedging of the vertebral body, and may be demonstrated by further radiographic examination. The clinical significance is uncertain, but one patient is presented in whom unilateral spondylolysis was associated with intermittent sciatic pain.

An acute abdomen: spontaneous rupture of liver during pregnancy

Spontaneous rupture of liver during pregnancy is presented as an example of an acute abdomen admitted to a casualty department of a general hospital. The literature is reviewed and emphasis is placed on clinical awareness and earlier diagnosis as a means to reduce the high mortality.

Regulation of cell cycle stage-specific transcription of histone genes from chromatin by non-histone chromosomal proteins

RNA transcripts from chromatin of S phase but not G1 cells contain histone-specific sequences. Chromatin reconstituted with S phase non-histone chromosomal proteins transcribes histone messenger RNA sequences whereas chromatin reconstituted with G1 non-histone proteins does not. These results suggest that transcription of histone genes is regulated during the cell cycle and that non-histone proteins have a key role in this regulation.

Clinical choriomatosis

Images