[Updated recommendations for vaccination in adults with respiratory diseases. Argentine Association of Respiratory Medicine, 2023]

Adult smokers, those with comorbidities, and the elderly, are at greater risk of contracting infections and their complications. Community acquired respiratory infections due to viruses, pneumococcus and other bacteria, affect both healthy and sick adults. There are vaccines that the pulmonologist must know and prescribe. The target strains of the influenza vaccine are defined by the WHO for the Southern hemisphere considering those involved in the previous influenza season in the Northern hemisphere. Its effectiveness depends on virulence, concordance between circulating and vaccine strains, and population coverage. The anti-pneumococcal polysaccharide vaccine available since 1983 is being replaced by more effective conjugate vaccines to prevent infections related to serotypes present in them. Immunization against SARS-CoV-2 reduced the contagion, severity, and lethality of COVID-19. The acellular vaccine against Bordetella pertussis for adults is present for specific situations in the adult calendar; vaccinating them strengthens the control of childhood contagion. The double (diphtheria + tetanus), and triple (double + pertussis) bacterial vaccines, and the vaccines against measles, chickenpox, rubella, human papillomavirus, Haemophilus influenzae, meningococcus, herpes zoster, Argentine hemorrhagic fever and yellow fever, are of a more limited use. Soon we will have new vaccines such as the one recently approved by the FDA against respiratory syncytial virus. Through a consensus of experts in respiratory infections, we review the new evidence regarding the immunization of adults who consult a pulmonologist, and thus update the recommendations on vaccination made eight years ago.

Qualitative cultures in ventilator-associated pneumonia - can they be used with confidence?

The sensitivity and specificity of the radiographic and clinical evidence used to diagnose ventilator-associated pneumonia vary depending on the number of clinical criteria present. Bacteriological confirmation that rules out other diseases can be achieved by quantitative or qualitative cultures of tracheal aspirate. The rate of tracheal colonization in ventilated patients reduces the usefulness of qualitative cultures, but the absence of multiresistant micro-organisms in cultures from patients on prior antibiotics or a sterile culture in patients without prior antimicrobials may provide sufficient justification to stop or de-escalate antibiotics. However, more accurate guidance regarding whether antibiotics are unnecessary and should be stopped is provided by quantitative culture.

Correlation between the 1.6 A crystal structure and mutational analysis of keratinocyte growth factor

A comprehensive deletion, mutational, and structural analysis of the native recombinant keratinocyte growth factor (KGF) polypeptide has resulted in the identification of the amino acids responsible for its biological activity. One of these KGF mutants (delta23KGF-R144Q) has biological activity comparable to the native protein, and its crystal structure was determined by the multiple isomorphous replacement plus anomalous scattering method (MIRAS). The structure of KGF reveals that it folds into a beta-trefoil motif similar to other members of fibroblast growth factor (FGF) family whose structures have been resolved. This fold consists of 12 anti-parallel beta-strands in which three pairs of the strands form a six-stranded beta-barrel structure and the other three pairs of beta-strands cap the barrel with hairpin triplets forming a triangular array. KGF has 10 well-defined beta strands, which form five double-stranded anti-parallel beta-sheets. A sixth poorly defined beta-strand pair is in the loop between residues 133 and 144, and is defined by only a single hydrogen bond between the two strands. The KGF mutant has 10 additional ordered amino terminus residues (24-33) compared to the other FGF structures, which are important for biological activity. Based on mutagenesis, thermal stability, and structural data we postulate that residues TRP125, THR126, and His127 predominantly confer receptor binding specificity to KGF. Additionally, residues GLN152, GLN138, and THR42 are implicated in heparin binding. The increased thermal stability of delta23KGF-R144Q can structurally be explained by the additional formation of hydrogen bonds between the GLN side chain and a main-chain carbonyl on an adjoining loop. The correlation of the structure and biochemistry of KGF provides a framework for a rational design of this potentially important human therapeutic.

Three-dimensional structures of acidic and basic fibroblast growth factors

Members of the fibroblast growth factor (FGF) family of proteins stimulate the proliferation and differentiation of a variety of cell types through receptor-mediated pathways. The three-dimensional structures of two members of this family, bovine acidic FGF and human basic FGF, have been crystallographically determined. These structures contain 12 antiparallel beta strands organized into a folding pattern with approximate threefold internal symmetry. Topologically equivalent folds have been previously observed for soybean trypsin inhibitor and interleukins-1 beta and -1 alpha. The locations of sequences implicated in receptor and heparin binding by FGF are presented. These sites include beta-sheet strand 10, which is adjacent to the site of an extended sequence insertion in several oncogene proteins of the FGF family, and which shows sequence conservation among the FGF family and interleukin-1 beta.

Color Doppler imaging of intracranial vessels in the neonate

This study was performed to examine the effectiveness of color Doppler imaging (CDI) in demonstrating the neonatal intracranial vessels and altered intracranial flow patterns and to determine the optimal approach in imaging and intracranial vasculature. The study was conducted in two parts. First, 14 neonates were examined with CDI by using a standard approach through the anterior fontanel. Whenever possible, views through the posterior fontanel and the temporal bone were obtained also. The anterior cerebral, M1 segment of the middle cerebral, distal internal carotid, and basilar arteries were demonstrated consistently. Portions of the vertebral distal middle cerebral, and posterior cerebral arteries were frequently visualized. In the second part of the study, we examined 10 neonates who had undergone extracorporeal membrane oxygenation. In this group of patients, CDI was able to demonstrate occlusion of the right internal carotid artery and the reversal of flow through the ipsilateral A1 segment. Increased flow on the contralateral side and in the basilar artery was observed in several patients. The anterior fontanel approach was shown to be the most useful in identifying most of the major intracranial arteries and veins with CDI. In addition, the body weights and gestational ages of the neonates were found to significantly influence the success rate in visualizing the intracranial vasculature.

Structure of the reaction center from Rhodobacter sphaeroides R-26 and 2.4.1: protein-cofactor (bacteriochlorophyll, bacteriopheophytin, and carotenoid) interactions

The three-dimensional structures of the cofactors and protein subunits of the reaction center (RC) from the carotenoidless mutant strain of Rhodobacter sphaeroides R-26 and the wild-type strain 2.4.1 have been determined by x-ray diffraction to resolutions of 2.8 A and 3.0 A with R values of 24% and 26%, respectively. The bacteriochlorophyll dimer (D), bacteriochlorophyll monomers (B), and bacteriopheophytin monomers (phi) form two branches, A and B, that are approximately related by a twofold symmetry axis. The cofactors are located in hydrophobic environments formed by the L and M subunits. Differences in the cofactor-protein interactions between the A and B cofactors, as well as between the corresponding cofactors of Rb, sphaeroides and Rhodopseudomonas viridis [Michel, H., Epp, O. & Deisenhofer, J. (1986) EMBO J. 3, 2445-2451], are delineated. The roles of several structural features in the preferential electron transfer along the A branch are discussed. Two bound detergent molecules of beta-octyl glucoside have been located near BA and BB. The environment of the carotenoid, C, that is present in RCs from Rb. sphaeroides 2.4.1 consists largely of aromatic residues of the M subunit. A role of BB in the triplet energy transfer from D to C and the reason for the preferential ease of removal of BB from the RC is proposed.