Lung abscess: an update on the current knowledge and call for future investigations

PURPOSE OF REVIEW

Lung abscess is a severe and complex respiratory infection. The purpose of this review is to discuss recent publications on lung abscess, covering topics such as epidemiology, clinical presentation, diagnosis, and treatment and prevention.

RECENT FINDINGS

Risk factors associated with lung abscess include structural lung disease, poor dental hygiene, and ventilator-associated pneumonia, while concerns are now raised regarding the potential of electronic cigarettes use as a risk factor. The complexity of lung abscess is reflected by the relative high number of case reports describing rare and complex cases. Early transthoracic drainage could improve in-hospital outcomes, while next-generation sequencing could become an important tool in diagnostics and future clinical studies.

SUMMARY

High-quality evidence and guidelines to support treatment of lung abscess are lacking. Despite advancements, we call for prospective studies to evaluate the use of invasive procedures and antibiotic treatment regimens.

Thrombelastography and Conventional Coagulation Markers in Chronic Obstructive Pulmonary Disease: A Prospective Paired-Measurements Study Comparing Exacerbation and Stable Phases

Chronic Obstructive Pulmonary Disease (COPD) exacerbation is known for its substantial impact on morbidity and mortality among affected patients, creating a significant healthcare burden worldwide. Coagulation abnormalities have emerged as potential contributors to exacerbation pathogenesis, raising concerns about increased thrombotic events during exacerbation. The aim of this study was to explore the differences in thrombelastography (TEG) parameters and coagulation markers in COPD patients during admission with exacerbation and at a follow-up after discharge. This was a multi-center cohort study. COPD patients were enrolled within 72 h of hospitalization. The baseline assessments were Kaolin-TEG and blood samples. Statistical analysis involved using descriptive statistics; the main analysis was a paired t-test comparing coagulation parameters between exacerbation and follow-up. One hundred patients participated, 66% of whom were female, with a median age of 78.5 years and comorbidities including atrial fibrillation (18%) and essential arterial hypertension (45%), and sixty-five individuals completed a follow-up after discharge. No significant variations were observed in Kaolin-TEG or conventional coagulation markers between exacerbation and follow-up. The Activated Partial Thromboplastin Clotting Time (APTT) results were near-significant, with p = 0.08. In conclusion, TEG parameters displayed no significant alterations between exacerbation and follow-up.

Twelve-month follow-up after hospitalization for SARS-COV-2: Physiology improves, symptoms remain

OBJECTIVES

Persistent symptoms on short-term follow-up after infection with COVID-19 are common, but long-term consequences have been insufficiently studied. The aim of this study was to characterize pulmonary function and ongoing symptoms 12 months after hospitalization with COVID-19.

METHODS

This prospective multicenter study included 222 patients hospitalized with PCR-confirmed COVID-19 in the Central Denmark Region. Disease severity was stratified using WHO Clinical Progression Scale. Clinical characteristics, pulmonary function test (PFT), 6-minute walk test (6MWT), and patient-reported outcome measures were collected at follow-up 3 and 12 months after discharge. Outcome measures from follow-up 3 months after discharge have previously been published.

RESULTS

A total of 179 (81%) patients completed the 12-month follow-up. Median age was 60 years (IQR 51, 69) and 58% were male patients. At 12-month follow-up 49.7% had a normal diffusion capacity for carbon monoxide (DLCO), while 39.4% had DLCO < 80%. The 6MWT distance increased significantly (29 m 95% CI 19, 40; p < 0.01). An mMRC score of 0 was reported by 51% and an mMRC ≥ 2 by 20%. The frequency and severity of fatigue, depression, and anxiety did not improve over time.

CONCLUSIONS

The study found that impaired DLCO percentage is common 12 months after hospitalization with SARS-CoV-2 and reduction in DLCO percentage is associated to dyspnea.

Lung abscess: Clinical characteristics of 222 Danish patients diagnosed from 2016 to 2021

INTRODUCTION

Lung abscess (LA) is a serious respiratory infection often followed by several weeks of antibiotic treatment. This study described the clinical presentation of LA, treatment duration and mortality in a contemporary Danish population.

METHODS

In a retrospective multicenter cohort study at four Danish hospitals, patients diagnosed with LA were identified using the International Classification of Diseases and Related Health Problems 10th revision (ICD-10) between 2016 and 2021. A predefined data collection tool was used to extract data on demographics, symptoms, clinical findings and treatment.

RESULTS

Of 302 patients, 222 with LA were included after review of patient records (76%). Mean age was 65 years (54-74), 62.9% was male and 74.9% were ever-smokers. Chronic obstructive pulmonary disease (COPD) (35.1%), use of sedatives (29.3%) and alcohol abuse (21.8%) were common risk factors. Dental status was reported in 51.4%, whereof 41.6% had poor dental status. Patients presented with cough (78.8%), malaise (61.3%) and fever (56.8%) Patients were hospitalized for a median of 14 days (interquartile ranges, IQR 7-21) and median duration of antibiotic treatment was 38 days (IQR 30-51). All-cause mortality after 1, 3 and 12 months was 2.7%, 7.7% and 15.8%, respectively.

CONCLUSION

Risk factors for LA include COPD and use of sedatives, alcohol abuse, and poor dental status. Despite long-term antibiotic treatment, long-term mortality is markedly high.

Fatigue Is a Major Symptom at COVID-19 Hospitalization Follow-Up

Persistent symptoms after hospitalization with COVID-19 are common, but the frequency and severity of these symptoms are insufficiently understood. We aimed to describe symptoms and pulmonary function after hospitalization with COVID-19. Patients hospitalized with COVID-19 in Central Denmark Region were invited for follow-up 3 months after discharge. Clinical characteristics, patient reported outcomes (Fatigue Assessment Scale (FAS), anxiety and depression (HADS)), symptoms, pulmonary function test and 6-min walk test were collected. We included 218 patients (mean age 59.9 (95% CI: 58.2, 61.7), 59% males). Fatigue, dyspnea and impaired concentration were the most prevalent symptoms at follow-up. Using FAS, 47% reported mild-to-moderate fatigue and 18% severe fatigue. Mean HADS was 7.9 (95% CI: 6.9, 8.9). FAS was correlated to HADS (β = 0.52 (95% CI: 0.44, 0.59, p < 0.001)). Mean DLCO was 80.4% (95% CI: 77.8, 83.0) and 45% had DLCO ˂ 80%. Mean DLCO was significantly reduced in patients treated in the ICU (70.46% (95% CI 65.13, 75.79)). The highest FAS and HADS were seen in patients with the shortest period of hospitalization (2.1 days (95% CI: 1.4, 2.7)) with no need for oxygen. In conclusion, fatigue is a common symptom after hospitalization for COVID-19 and ICU treatment is associated to decreased diffusion capacity.

[Bacterial lung abscesses]

A lung abscess is a necrotising infection leading to loss of healthy lung tissue. It develops over several weeks, and the typical presentation includes cough, fever, and general deterioration. The clinical work-up includes contrast-enhanced CT-scans, and frequently flexible bronchoscopy with broncho-alveolar lavage as described in this review. The infection commonly represents aspiration of oral bacterial flora, including anaerobic microbes. Penicillin resistance is common. A lung abscess generally requires long-term, tailored antibiotic treatment. The patient should consult a dentist to identify possible dental foci.

Rare nocardiosis in danish patient with diabetes

We herein report a rare case that describes and visualizes nocardiosis in a patient with diabetes. The patient presented with recurring fever, gout, leg pain, frailty and muscular pain through nine months, before a core needle biopsi, from an abscess in the abdominal musculature, revealed Nocardia Paucivorans. A PET-CT-scan showed multiple muscular FDG-positive sites. Furthermore, he experienced serious side effects to Sulfametoxazole and Trimethoprim, the antibiotic of choice for this type of infection. He was then switched to Moxifloxacin and Ampicillin. Nocardia often presents as opportunistic infections, typically in patients with severe immunodeficiencies, such as HIV, use of high-dose corticosteroids, hematologic malignancies or immunosuppression following organ transplantation. This case illustrates how a patient with only relative immunodeficiency gets rare nocardiosis. Our sparse knowledge on clinical presentation is based on case-reports and treatment is empirical. Hence, a better understanding of the clinical presentation and treatment is important. Especially given the prospect, that the health care system faces a greater load of patients with diabetes and other immunodeficiencies in the future.

Revisiting adult neurogenesis and the role of erythropoietin for neuronal and oligodendroglial differentiation in the hippocampus

Recombinant human erythropoietin (EPO) improves cognitive performance in neuropsychiatric diseases ranging from schizophrenia and multiple sclerosis to major depression and bipolar disease. This consistent EPO effect on cognition is independent of its role in hematopoiesis. The cellular mechanisms of action in brain, however, have remained unclear. Here we studied healthy young mice and observed that 3-week EPO administration was associated with an increased number of pyramidal neurons and oligodendrocytes in the hippocampus of ~20%. Under constant cognitive challenge, neuron numbers remained elevated until >6 months of age. Surprisingly, this increase occurred in absence of altered cell proliferation or apoptosis. After feeding a ¹⁵N-leucine diet, we used nanoscopic secondary ion mass spectrometry, and found that in EPO-treated mice, an equivalent number of neurons was defined by elevated ¹⁵N-leucine incorporation. In EPO-treated NG2-Cre-ERT2 mice, we confirmed enhanced differentiation of preexisting oligodendrocyte precursors in the absence of elevated DNA synthesis. A corresponding analysis of the neuronal lineage awaits the identification of suitable neuronal markers. In cultured neurospheres, EPO reduced Sox9 and stimulated miR124, associated with advanced neuronal differentiation. We are discussing a resulting working model in which EPO drives the differentiation of non-dividing precursors in both (NG2+) oligodendroglial and neuronal lineages. As endogenous EPO expression is induced by brain injury, such a mechanism of adult neurogenesis may be relevant for central nervous system regeneration.

Abstract P4-10-17: Changes of bone turnover markers during perioperative anthracycline- and/or taxane-based chemotherapy in pre- and postmenopausal patients with primary breast cancer

Background: Loss of bone mineral density (BMD) is among the well known sequelae of pharmacological therapy of patients (pts) with primary breast cancer (PBC). Cancer therapy induced bone loss (CTIBL) progresses more rapidly as compared to normal age-related changes of BMD and is best known to be associated with aromatase inhibitors in postmenopausal pts. Chemotherapy (Ctx) may also lead to a deterioration of BMD but in contast to endocrine Tx, this phenomenon is by far less elucidated and, at least in younger pts, mostly interpreted as a secondary effect following Ctx induced ovarian failure. Previous investigations focused on the classical CMF scheme, whereas conclusive data regarding direct effects of more recent Ctx protocols on the bone metabolism of PBC pts are still lacking. This translational project was initiated to gain detailed insights into the influence of anthracycline (A)- and/or taxane (T)-based Ctx on bone turnover of both pre- and postmenopausal PBC pts in the clinical routine. Methods: Data of 109 pts (premenopausal: 49; postmenopausal: 60) with non-metastatic Ctx-naïve PBC exposed to neoadjuvant or adjuvant Ctx were analyzed. 84 pts (75%) had estrogen receptor-positive (ER+) disease, HER2- overexpression was found in 18 pts (17%). 16 pts (15%) received A-based Ctx, 34 pts (31%) received T-based Ctx, and 59 pts (54%) received A/T-based Ctx. Trastuzumab was given to 17 pts (16%) with HER2-positive disease. Serum bone markers including the C-telopeptide of type I collagen (ICTP) indicating osteoclast activity, the N-propeptide of type I collagen (P1NP) measuring osteoblast activity, and alkaline phosphatase (AP) were determined at baseline and prior to each subsequent Ctx cycle (C) up to C6. Changes of ICTP, P1NP, and AP over time were analyzed by repeated-measure ANOVA. Results: 600 Ctx cycles were analyzed. Baseline levels of ICTP (p = 0.0027), P1NP (p = 0.0063), and AP (p = 0.0007) were significantly higher in post- versus premenopausal pts. AP levels remained largely unchanged during Ctx. Trends showing an increase of ICTP from baseline until C6 in premenopausal pts and a decrease in postmenopausal pts did not reach statistical significance. In contrast, P1NP significantly declined in postmenopausal pts from baseline to C6 (p = 0.0152). In premenopausal pts, P1NP declined from baseline to C3 and thereafter increased to C6. These changes were highly significant (p = 0.0024). Conclusions: Our study represents one of the first systematic evaluations of bone turnover in pts exposed to modern A- and/or T-based Ctx for PBC in the clinical routine. Postmenopausal pts presented with higher baseline levels of all three markers which may be attributable to an enhanced bone turnover related to the loss of ovarian function prior to the initiation of Ctx. In postmenopausal pts, Ctx was associated with a sustained suppression of osteoblast activity whereas osteoblast suppression recovered until the end of Ctx in premenopausal pts. Whether these effects will translate into an increased risk of CTIBL remains a matter of further investigations which should clearly focus on the individual menopausal status.

Citation Format: Kurbacher CM, Rauschenbach N, Kurbacher AT, Sperling S, Herz S, Monreal K, Kurbacher JA. Changes of bone turnover markers during perioperative anthracycline- and/or taxane-based chemotherapy in pre- and postmenopausal patients with primary breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-10-17.

Positive and negative bioimprinted polymeric substrates: new platforms for cell culture

Bioimprinting, which involves capturing cell morphological details into a polymer matrix, provides a new class of patterned surfaces which opens an opportunity to investigate how cells respond to their own signatures and may introduce possibilities for regulating their behaviour. In this study, phenotypic details of human nasal chondrocytes (HNCs) were replicated in soft polydimethylsiloxane (PDMS) mould resulting in inverse replicas of cells, which have been termed here as 'negative bioimprint'. For the first time, the information from this negative bioimprint was then transferred into another PDMS layer resulting in surfaces which resemble cell morphology and were called 'positive bioimprints'. Soft lithography was used to transfer these details from PDMS into different polymers like polystyrene, tissue culture polystyrene and clinically used block co-polymer poly (ethylene glycol) terephthalate-poly (butylene terephthalate) (PEGT-PBT). Results obtained from surface characterization confirmed that fine details of cells were successfully replicated from cells to different polymer matrices without any significant loss of information during the different steps of pattern transfer. HNCs seeded on different polymer surfaces with positive and negative bioimprints exhibited distinct behaviour. Cells cultured on positive bioimprints were more spread out and displayed high levels of proliferation compared to those on negative bioimprints, where cells were more compact with lower proliferation.

Neuropsychiatric disease relevance of circulating anti-NMDA receptor autoantibodies depends on blood-brain barrier integrity

In 2007, a multifaceted syndrome, associated with anti-NMDA receptor autoantibodies (NMDAR-AB) of immunoglobulin-G isotype, has been described, which variably consists of psychosis, epilepsy, cognitive decline and extrapyramidal symptoms. Prevalence and significance of NMDAR-AB in complex neuropsychiatric disease versus health, however, have remained unclear. We tested sera of 2817 subjects (1325 healthy, 1081 schizophrenic, 263 Parkinson and 148 affective-disorder subjects) for presence of NMDAR-AB, conducted a genome-wide genetic association study, comparing AB carriers versus non-carriers, and assessed their influenza AB status. For mechanistic insight and documentation of AB functionality, in vivo experiments involving mice with deficient blood-brain barrier (ApoE(-/-)) and in vitro endocytosis assays in primary cortical neurons were performed. In 10.5% of subjects, NMDAR-AB (NR1 subunit) of any immunoglobulin isotype were detected, with no difference in seroprevalence, titer or in vitro functionality between patients and healthy controls. Administration of extracted human serum to mice influenced basal and MK-801-induced activity in the open field only in ApoE(-/-) mice injected with NMDAR-AB-positive serum but not in respective controls. Seropositive schizophrenic patients with a history of neurotrauma or birth complications, indicating an at least temporarily compromised blood-brain barrier, had more neurological abnormalities than seronegative patients with comparable history. A common genetic variant (rs524991, P=6.15E-08) as well as past influenza A (P=0.024) or B (P=0.006) infection were identified as predisposing factors for NMDAR-AB seropositivity. The >10% overall seroprevalence of NMDAR-AB of both healthy individuals and patients is unexpectedly high. Clinical significance, however, apparently depends on association with past or present perturbations of blood-brain barrier function.

A single gene defect causing claustrophobia

Claustrophobia, the well-known fear of being trapped in narrow/closed spaces, is often considered a conditioned response to traumatic experience. Surprisingly, we found that mutations affecting a single gene, encoding a stress-regulated neuronal protein, can cause claustrophobia. Gpm6a-deficient mice develop normally and lack obvious behavioral abnormalities. However, when mildly stressed by single-housing, these mice develop a striking claustrophobia-like phenotype, which is not inducible in wild-type controls, even by severe stress. The human GPM6A gene is located on chromosome 4q32-q34, a region linked to panic disorder. Sequence analysis of 115 claustrophobic and non-claustrophobic subjects identified nine variants in the noncoding region of the gene that are more frequent in affected individuals (P=0.028). One variant in the 3'untranslated region was linked to claustrophobia in two small pedigrees. This mutant mRNA is functional but cannot be silenced by neuronal miR124 derived itself from a stress-regulated transcript. We suggest that loosing dynamic regulation of neuronal GPM6A expression poses a genetic risk for claustrophobia.

The surface coat on human corneal endothelium

Scanning electron microscopy of human cadaver corneas revealed a selective binding of ruthenium red-osmium tetroxide to some substance coating the posterior endothelial surface. A coating material was not found on autolyzed cells, on denuded areas of the membrane of Descemet, or on the anterior surface of endothelial cells. Partial digestion of the coating material by urokinase and trypsin suggests the presence of at least three different structural or chemical elements.

Endothelial morphology related to disease activity in human corneas

Twenty normal and four groups of pathological corneas with the diagnoses aphakia, macula after herpetic keratitis. Fuchs' endothelial dystrophy and graft rejection were stained with trypane blue and alizarin red. The morphology of the endothelium was described in terms of cell density, coefficient of variation for cell area, percentage of hexagonal cells, percentage of joint meetings of more than three cells, nuclei per cell and nuclear shape. The groups of aphakia, keratitis, Fuchs' dystrophy and graft rejection were considered to represent increasing degrees of endothelial disease activity at the time of evaluation. The only parameter showing consistent variation with disease activity was the percentage of joint meetings of more than three cells.

The transcriptional landscape of the mammalian genome

This study describes comprehensive polling of transcription start and termination sites and analysis of previously unidentified full-length complementary DNAs derived from the mouse genome. We identify the 5' and 3' boundaries of 181,047 transcripts with extensive variation in transcripts arising from alternative promoter usage, splicing, and polyadenylation. There are 16,247 new mouse protein-coding transcripts, including 5154 encoding previously unidentified proteins. Genomic mapping of the transcriptome reveals transcriptional forests, with overlapping transcription on both strands, separated by deserts in which few transcripts are observed. The data provide a comprehensive platform for the comparative analysis of mammalian transcriptional regulation in differentiation and development.

Molar incisor hypomineralisation in a group of children and adolescents living in Dresden (Germany)

AIM

This was to determine the prevalence of Molar Incisor Hypomineralisation (MIH) and to evaluate possible causes of these enamel defects.

METHODS

The study group consisted of 2,408 10-17 year old children born during 1985-1992 and living in Dresden (Germany). Enamel defects were recorded using the modified DDE index. Children with enamel defects and their parents were invited for a re-examination to record the medical history of the children during the first 3 years of life; these children were matched by age with other children with apparently normal first molars (control group).

RESULTS

135 (5.6%) of the children had demarcated opacities in at least one first molar, i.e. MIH. A significantly higher prevalence of MIH was seen in children born between 1989 and 1991 compared with those born before and after that period (p<0.01). The number of children returning for the medical history questionnaire was low, 31 out of 135 responded (test group). Although there were no significant differences between the test and control groups in terms of peri and neonatal complications or other health problems, the low return precluded any definitive interpretation.

CONCLUSION

The overall prevalence of MIH in this study was low by comparison with other previous epidemiological reports.

Triple A syndrome is caused by mutations in AAAS, a new WD-repeat protein gene

The triple A syndrome (MIM 231550) is a rare autosomal recessive disorder characterized by adrenal insufficiency, achalasia and alacrima. The frequent association with a variety of neurological features may result in a severely disabling disease. We previously mapped the syndrome to a 6 cM interval on chromosome 12q13 and have now refined the critical region to 0 cM between KRT8 and D12S1651. Overlapping bacterial artificial chromosome (BAC) sequences of a high resolution BAC/P1-derived artificial chromosome (PAC) contig were screened for gene content and a novel gene encoding a 546 amino acid polypeptide was identified. In nine triple A syndrome patients eight different homozygous and compound heterozygous mutations were found in this gene, most of them leading to a truncated protein suggesting loss of function. RNA blotting experiments revealed marked expression in neuroendocrine and gastrointestinal structures, which are predominantly affected in triple A syndrome, supporting the hypothesis that mutations in this triple A syndrome gene (AAAS) are responsible for the disease. The predicted protein belongs to the family of WD repeat-containing proteins which exhibit a high degree of functional diversity including regulation of signal transduction, RNA processing and transcription.

The swelling pressure of the human corneal stroma as determined by a new method

The swelling pressure of 115 human corneas was determined using a modified electronic balance modified to simultaneously record the swelling force and the thickness of the stroma. The swelling force was found to follow a straight-line dependence on the stromal thickness when plotted in a double logarithmic scale, which means that the swelling pressure of each cornea could be expressed by a power fit of the form SP = aTb, where SP is swelling pressure, T stromal thickness, and a and b are constants of the cornea. In 45 control corneas swollen in 0.9% NaCl, pH 7.4, 0.01 M Hepes buffer, the mean value (+/- S.D.) of 'a' and 'b' were 7.09 mmHg mm-1 (+/- 2.96) and -3.48 (+/- 0.20), respectively. This corresponded to a mean swelling pressure of 84.0 mmHg at a standard stromal thickness of 0.5 mm. In paired experiments, the swelling pressure was found to be influenced insignificantly (P greater than 0.05) by a number of conditions, including lowering the pH to 4.0, increasing the temperature to 37 degrees C, and increasing the NaCl concentration to 9%. A significant correlation was found between the swelling pressure and the dry weight of the specimen (P less than 0.05), indicating a considerable biological variation of the swelling pressure. It is shown, that this variation may explain the normal variation in human corneal thickness in vivo.

Evaluation of the endothelium of human donor corneas by induced dilation of intercellular spaces and trypan blue

The endothelium of 30 pairs of human cadaver corneas was stained by trypan blue and the intercellular spaces were visualized by induced dilation prior to corneal culture. Trypan blue staining and induced dilation of intercellular spaces by 0.9% and 0.45% NaCl were found to be atraumatic. Only a fraction of damaged cells were stained by trypan blue. Endothelial cell losses in culture did not correlate with the number of trypan-blue stained cells, the post-mortem time, or donor age.

Electron microscopy of cultured human corneas. Osmotic hydration and the use of a dextran fraction (dextran T 500) in organ culture

Human corneas were studied by means of electron microscopy after culture at 31 degrees C for two to 20 days in a medium containing 8% dextran T 500. Dextran T 500, a strong osmotic agent, was included in the culture medium to prevent excessive swelling of the cornea. In order to exclude the possibility that the observed effects were the result of osmotic changes during fixation, in each experiment, fixatives with different osmolalities were used (430, 574, 727, and 812 mOsm). After 8, 16, and 20 days of culture, vacuoles appeared that were filled with dextran; the cytoplasm was completely filled with these vacuoles. The vacuolization was not limited to the endothelium, but was also observed in stromal keratocytes and to a limited extent in the epithelium. It was concluded that the monolayer of endothelium was still intact after 20 days of culture in medium containing 8% dextran T 500, and, secondly, that the dextran might have been taken up by endocytosis. Whether or not the uptake of dextran has a long-term toxic effect on the corneal cells remains to be elucidated.

Ultrastructure of cryopreserved, functioning human corneal endothelium

The endothelium was studied by light- and electronmicroscopy in a cryopreserved cornea transplanted to a woman with herpetic keratitis and removed after 18 months because of wound dehiscence and epithelialization of the anterior chamber. The graft was perfectly transparent and of normal thickness. Light microscopy revealed the existence of a continuous layer of endothelial cells, showing pronounced pleomorphism when examined in flat preparation, with large multinuclear cells between smaller more normal looking mononuclear cells. The heterogeneous cell pattern resembled that observable in vitro after freezing and 24 h of culture. The cells therefore are not considered to be in a steady state. The ultrastructure of the majority of the cells was similar to that of non-cryopreserved endothelium. Cell cohesion took place by tight junctions, the intercellular spaces were of normal width. Ultrastructurally there was, however, a cellular heterogeneity, due to the occurrence of light cells with few organelles, but always with intact cell membranes. These cells probably represent slow death of endothelial cells, demonstrated by falling cell density during the 18 months between grafting and examination. We conclude from this study that cells surviving the freezing can maintain a clinically normal endothelial function for 18 months by forming a continuous quasistatic monolayer of tightly bound living cells.

Post-operative thickness and endothelial cell density in cultivated, cryopreserved human corneal grafts

Seventeen corneas obtained 2-72 h post mortem, from donors aged 17-78 years, were cultivated for 24 h, cryopreserved, thawed, cultivated for another 24 h and grafted. One year post-operatively 12 of the 17 grafts were clear. In 10 of these 12 cases the visual acuity was greater than or equal to 0.33. One primary graft failure occurred, while 4 primarily clear grafts became cloudy due to glaucoma (2), phthisis bulbi (1) and herpetic reinfection (1). One year after the transplantations the central thickness of the clear grafts was 0.51 mm, and the endothelial cell density was 1028 cells/mm2, corresponding to 32% of the cell density before cryopreservation. This endothelial cell loss was not correlated to donor age or to the time between the death of the donor and the primary cultivation.

Human corneal endothelial cell density after an in vitro imitation of elevated intraocular pressure

Normal human cadaver corneas were mounted in test chambers 10-52 h post mortem, regenerated for 24 h in a modified tissue culture medium, and exposed to a laboratory imitation of elevated intraocular pressure. The endothelial cell density was determined before application of the pressure and after 24 h of culture without a pressure difference between the anterior and the posterior corneal surfaces. Pressure differences of 160 and 80 mmHg maintained for 8 and 72 h did not lead to decreased endothelial cell densities.

Fresh and cultured corneal grafts compared by post-operative thickness and endothelial cell density

Thirty-nine corneas were removed within 6 h post mortem and stored in a moist chamber at 4 degrees C before grafting. The mean donor age was 33 years and the average time between death and grafting was 11 h. Thirty cadaver corneas were selected after trypane blue staining and cultured at 31 degrees C for 24 h before grafting. The mean donor age was 61 years and the mean time between death and culture was 18 h. During the first 10 postoperative days fresh grafts were thinner than cultured grafts. One year after the transplantation the two groups did not differ significantly in regard to the clinical result, corneal thickness, or endothelial cell loss. This indicates that corneas from old donors with extended post mortem time can be used for transplantation after individual evaluation and corneal culture.

A simple apparatus for controlled rate corneal freezing II

A corneal freezer without electrical or mechanical function is described. Cooling is achieved by partial immersion of the freezing unit in liquid nitrogen. The cooling rate is controlled by the heat content in the unit and the facility for heat removal from the unit. Corneas are frozen in aluminum vials. Corneas are thawed in less than 30 sec without risk of over heating, when the vials are placed on the metal core of another freezing unit at room temperature.

Cryopreservation of human cadaver corneas regenerated at 31 degrees C in a modified tissue culture medium

Human corneas were obtained 2-82 h post mortem, cultured for 20-28 h, in a modified tissue culture medium, frozen at a controlled rate, and thawed rapidly. The thawed corneas were subjected to 20-28 h of additional culture. Immediately after thawing, a mean endothelial cell damage of 11% was indicated by trypane blue staining. The mean endothelial cell loss during the subsequent culture was 34%. This cell loss was not related to post mortem time, to donor age, to cell loss during the primary culture, or to endothelial cell density.

Thymidine incorporation by human corneal endothelium during organ culture

Nine corneas from 5 human adult donors were obtained 11 to 31 h post mortem. In 4 corneas the endothelium was wounded by freezing and in 1 cornea by mechanical means. Care was taken to minimize endothelial damage in the remaining 4 corneas. The corneas were incubated at 31 degrees C for 6 days in a tissue culture medium containing 3H thymidine. Autoradiographs were made of the flat preparations of the endothelium. All corneas contained radioactive endothelial cell nuclei, with the highest concentration of labelled nuclei being in the wound areas. The greatest number of labelled cells was found in the cornea from the youngest donor, 19 years of age, but thymidine uptake also occurred in the oldest cornea, 89-years-old, which additionally had signs of endothelial dystrophy.

Decontamination of cadaver corneas

Bacterial contamination of human corneas, in vivo and post mortem, was investigated. Bacterial samples were obtained by pressing small concave agar plates directly against the corneas. More colony forming units (C.F.U.) occurred in samples obtained from patients in general anesthesia than in samples obtained from healthy persons in local anaesthesia. The largest number of C.F.U. occurred post mortem. The number of C.F.U. obtained from cadaver corneas was not correlated to post mortem time. Rinsing with water removed 86% of the C.F.U. on cadaver corneas. Rinsing with water for 30 sec followed by 2 min treatment with 0.5% polyvinylpyrrolidone-iodine (PVP-I) and repeated rinsing removed 98% of the C.F.U. Epithelial or stromal lesions were not found after 2 min of exposure to 0.5% PVP-I.

Endothelial cell density in donor corneas

In 68 pairs of donor corneas the endothelial cells were visualized by provoked swelling of the cell borders in isotonic saline. In cornea from donors below 50 years of age numerical cell density was correlated to age. This was not the case in corneas from older donors. The cell densities in paired corneas were correlated. The cell density in the second cornea of a pair was found to be within x +/- 10.97% (+/-1.98SD) of the first cornea. The precision of this estimate could only be improved insignificantly by correction for age, sex, mean cell density or variation of the mean.

Toxicity of dimethylsulfoxide (DMSO) to human corneal endothelium in vitro

Human cadaver corneas were obtained 10--12 h after clinical death, incubated in organ culture for 20--28 h and exposed 2, 4, 6, 8, 6, 4, and 2% DMSO successively for 10 min at each concentration. Endothelial cell damage was recognized by morphological alterations during reformation of a coherent cell sheat after expulsion of damaged cells. DMSO was found to cause latent cell damage at 31 degrees C. No cell damage was found at 4 degrees C when DMSO was dissolved in minimum essential medium (Eagle) plus Dextran or when DMSO was dissolved in human albumin plus sucrose. DMSO was found to be toxic at 4 degrees C in pure serum and in Dulbecco's medium.

Human corneal endothelium in organ culture. The influence of temperature and medium of incubation

Forty-four human corneas from patients between 21 and 86 years were incubated in Eagle's minimum essential medium with Earle's salts 10--46 h post mortem. The influence of incubation temperature and composition of the medium on endothelial survival was evaluated. Whole corneas were stained by alizarine red. Recent cell loss was indicated by morphological alterations in the endothelial pattern. After 20--28 h of incubation minimum cell loss was found at 31 degrees C when 8% Dextrane-250 and 20% serum or 8% Dextrane-500 and 10% serum was added to the medium.

Early morphological changes in organ cultured human corneal endothelium

Nineteen human cadaver corneas with few damaged endothelial cells were incubated under tissue culture conditions for time periods ranging from five min to 48 h. Morphological alterations of the endothelial cells were studied in whole wet mounts stained by alizarine red-alkohol-trypane blue and by scanning electron microscopy. Joint meetings of three cells are characteristic for normal corneal endothelium. After 15--60 min of incubation, damaged cells were expelled from the coherent cell sheet by expanding neighbouring cells. Joint meetings of 5--8 expanding cells were formed. After 24 h of incubation, joint meetings of four cells were the dominating morphological abnormality. Morphological changes during reduction of the numbers of cells in joint meetings are described.

The precision of unbiased estimates of numerical density of endothelial cells in donor cornea

The precision of estimates of central corneal endothelial density was studied in 16 human corneas stained by alizarine red and trypane blue. Estimates based on central counts and estimates based on peripheral counts were considered separately. The numerical density was estimated employing an unbiased sampling technique. From central counts estimates with an error of less than five per cent could be obtained. From peripheral counts a maximum precision of mean +/- 12.2 per cent could be obtained. The theoretical maximum precision was calculated by application of a variance component model. The precision of estimates was calculated for 1, 2 and 4 test areas of different sizes. Economy of sampling was evaluated by comparison of the actual precision to the theoretical maximum precision of estimates.

Indirect evaluation of corneal endothelial cell density

In 16 whole flat corneal mounts stained by alizarine red and trypane blue it was investigated whether estimates of central numerical endothelial cell density could be based on peripheral cell density, on age or on morphological cell characteristics. With certain precautions estimates of central cell density could be based on peripheral cell density, on age and on the occurrence of large central or peripheral cells. Estimates could not be based on the occurence of other cellular morphological characteristics.

Scanning electron microscopic observations of a mucopolysaccharide coating on human corneal endothelium

Scanning electron microscopic observations of human corneal endothelium revealed a binding of ruthenium red-osmium tetroxide to a material on the inner surface of the endothelial cells on the cornea and the trabecular meshwork. The coating material was partially digested by proteolytic enzymes.

Polysaccharide coating of human corneal endothelium

Electron microscopy revealed the presence of a 600-1500 A thick layer of polysaccharide on the surface of human corneal endothelial cells. The surface layer was visualized by combined fixation and staining in a mixture of ruthenium red and osmium tetroxide. The coating material was stable for at least 39 h post mortem and was retained on disintegrating cells.

A simple apparatus for controlled rate corneal freezing

The construction and operation of an apparatus for controlled rate corneal freezing is described. The cooling is obtained by close thermal contact between a vial holding the cornea and a metal core. A predetermined cooling rate is achieved by partial immersion of the core in a fixed amount of liquid nitrogen. In a preliminary series greater than or equal to 95% endothelial survival was obtained.