One-year follow-up of COVID-19 recoverees with impaired pulmonary function: A prospective cohort study

Decreased diffusion capacity for carbon monoxide (DLCO) is the most prevalent pulmonary testing abnormality among COVID-19 recoverees. We prospectively followed 51 individuals with impaired DLCO at an average of ∼3 months following COVID-19 and re-examined them at one year. At follow-up, mean DLCO increased from 68.0 % to 72.6 % (p = 0.002); while 33 % of the cohort experienced a clinically significant rise (>10 points) in DLCO, only 29 % normalized their values. While DLCO change did not correlate with symptoms, lack of improvement was more prevalent among individuals with obesity. Regardless of COVID-19 severity, a substantial proportion continued to exhibit DLCO impairment at 1-year.

Long COVID sexual dysfunction among both genders: Evaluation of a cohort of COVID-19 recoverees

OBJECTIVES

We aimed to assess Long COVID sexual dysfunction among both sexes.

PATIENTS AND METHODS

A cross-sectional study at a multidisciplinary COVID clinic. Consecutive patients answered a symptom-based questionnaire, which included sexual dysfunction. Individuals reporting any degree of sexual dysfunction were compared with those who denied. A multivariable logistic regression was conducted to identify risk factors. A principal component analysis was implemented to explore other symptoms associated with sexual dysfunction.

RESULTS

All in all, 391 individuals recovering from COVID-19 completed the questionnaire, 211 women and 180 men. Mean age was 45.2 (SD 15.4) years. Most (280, 85.9%) had mild COVID-19, assessed at a median of 3.8 (IQR 2.0) months from diagnosis. Sexual dysfunction was reported by 55 (36%) of the men and 48 (28%) of the women. Increased age [per year; men OR 1.05 (95% CI 1.02-1.08)], long COVID cough [men 2.58 (1.05-6.32)], chest pain [women 3.54 (1.28-9.80)], irritability [women 3.45 (1.28-9.29)], paresthesia [men 4.23 (1.55-10.44); women 3.08 (1.14-8.32)], and emotional distress [men 3.26 (1.36-7.82); women 4.29 (1.65-11.18)] were significantly associated with sexual dysfunction. In women, sexual dysfunction was part of the emotional pattern, while among men, it was part of the emotional and pulmonary patterns.

CONCLUSION

Sexual dysfunction is a common manifestation of long COVID in both men and women. Presence of other long COVID symptoms, and older age, are associated with this phenomenon. Further studies should explore the mechanisms for long COVID sexual dysfunction in both men and women, as well as strategies for prevention and treatment.

Immunogenicity and Safety of Modified Vaccinia Ankara (MVA) Vaccine-A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Prevention of mpox has become an important public health interest. We aimed to evaluate the safety and immunogenicity of the Modified Vaccinia Ankara (MVA) vaccine. We conducted a systematic review and meta-analysis of randomized-controlled trials (RCTs) comparing MVA versus no intervention, placebo, or another vaccine. Outcomes included safety and immunogenicity outcomes. We also performed a systematic review of RCTs evaluating various MVA regimens. Fifteen publications were included in the quantitative meta-analysis. All but one (ACAM2000) compared MVA with placebo. We found that cardiovascular adverse events following two MVA doses were significantly more common compared to placebo (relative risk [RR] 4.07, 95% confidence interval [CI] 1.10-15.10), though serious adverse events (SAEs) were not significantly different. Following a single MVA dose, no difference was demonstrated in any adverse event outcomes. Seroconversion rates were significantly higher compared with placebo after a single or two doses. None of the RCTs evaluated clinical effectiveness in preventing mpox. This meta-analysis provides reassuring results concerning the immunogenicity and safety of MVA. Further studies are needed to confirm the immunogenicity of a single dose and its clinical effectiveness. A single vaccine dose may be considered according to vaccine availability, with preference for two doses.

Duration of antibiotic treatment for Gram-negative bacteremia - Systematic review and individual participant data (IPD) meta-analysis

BACKGROUND

We aim to compare the effect of short versus long treatment duration in Gram-negative bacteremia on all-cause mortality in pre-specified sub-groups.

METHODS

Individual participant data meta-analysis of randomized controlled trials (RCTs) comparing short (≤7) versus longer (>7 days) antibiotic treatment for Gram-negative bacteremia. Participants were adults (≥18 years), with Gram-negative bacteremia during hospital stay. We searched PubMed, Cochrane Central Register of Controlled Trials, and Web of Science to identify trials conducted up to May 2022. Primary outcome was 90-day all-cause mortality. Secondary outcomes were 30-day mortality, relapse of bacteremia, length of hospital stay, readmission, local or distant infection complications, adverse events, and resistance emergence.Outcomes were assessed in pre-specified subgroups: women vs men; non-urinary vs urinary source; presence vs absence of hypotension on initial presentation; immunocompromised patients versus non-immunocompromised patients, and age (above/below 65). Fixed-effect meta-analysis model was used to estimate pooled odds ratio (OR) and 95% confidence interval (CI). All three trials had low risk of bias for allocation generation and concealment.

FINDINGS

Three RCTs (1186 patients) were included; 1121 with enterobacterales bacteremia. No significant difference in mortality was demonstrated between 7- and 14-days treatment (90-day mortality: OR 1.08, 95% CI 0.73-1.58; 30-day mortality: 1.08, 0.62-1.91). Relapse (1.00, 0.50-1.97); length of hospital stay (P = 0.78); readmission (0.96, 0.80-1.22); and infection complications (local: 1.62 0.76-3.47; distant: 2.00, 0.18-22.08), were without significant difference, and so were adverse events or resistance emergence.No significant difference in clinical outcomes between 7 and 14 days of antibiotics was demonstrated in the subgroups of gender, age, hemodynamic status, immune status, and source of infection.

INTERPRETATION

For patients hemodynamically stable and afebrile at 48 h prior to discontinuation, seven days of antibiotic therapy for enterobacterales bacteremia result in similar outcomes as 14 days, in terms of mortality, relapse, length of hospital stay, complications of infection, resistance emergence, and adverse events. These results apply for any adult age group, gender, source of infection, immune status, and hemodynamic status on presentation.

FUNDING

There was no funding source for this study.

Assessment of Adult Patients with Long COVID Manifestations Suspected as Cardiovascular: A Single-Center Experience

Background: Persistent symptoms affect a subset of coronavirus disease 2019 (COVID-19) survivors. Some of these may be cardiovascular (CV)-related. Objective: To assess the burden of objective CV morbidity among, and to explore the short-term course experienced by, COVID-19 patients with post-infectious symptomatology suspected as CV. Methods: This was a single-center, retrospective analysis of consecutive adult patients with new-onset symptoms believed to be CV following recovery from COVID-19, who had been assessed at a dedicated ‘Cardio’-COVID clinic between June 2020 and June 2021. All participants were followed for 1 year for symptomatic course and the occurrence of new CV diagnoses and major adverse cardiovascular events (MACE). Results: A total of 96 patients (median age 54 (IQR, 44–64) years, 52 (54%) females) were included in the final analysis. Initial visits occurred within a median of 142 days after the diagnosis of acute COVID. Nearly all (99%) patients experienced a symptomatic acute illness, which was graded as severe in 26 (27%) cases according to the National Institutes of Health (NIH) criteria. Long-COVID symptoms included mainly dyspnea and fatigue. While the initial work-up was mostly normal, 45% of the 11 cardiac magnetic resonance studies performed revealed pathologies. New CV diagnoses were made in nine (9%) patients and mainly included myocarditis that later resolved. An abnormal spirometry was the only variable associated with these. No MACE were recorded. Fifty-two (54%) participants felt that their symptoms improved. No association was found between CV morbidity and symptomatic course. Conclusions: In our experience, long-COVID symptoms of presumed CV origin signified actual CV disease in a minority of patients who, irrespective of the final diagnosis, faced a fair 1-year prognosis.

Characteristics of long-COVID among older adults: a cross-sectional study

OBJECTIVES

To describe long-COVID symptoms among older adults and to assess the risk factors for two common long-COVID symptoms: fatigue and dyspnea.

METHODS

This is a multicenter, prospective cohort study conducted in Israel, Switzerland, Spain, and Italy. Individuals were included at least 30 days after their COVID-19 diagnosis. We compared long-COVID symptoms between elderly (aged >65 years) and younger individuals (aged 18-65 years) and conducted univariate and multivariable analyses for the predictors of long-COVID fatigue and dyspnea.

RESULTS

A total of 2333 individuals were evaluated at an average of 5 months (146 days [95% confidence interval 142-150]) after COVID-19 onset. The mean age was 51 years, and 20.5% were aged >65 years. Older adults were more likely to be symptomatic, with the most common symptoms being fatigue (38%) and dyspnea (30%); they were more likely to complain of cough and arthralgia and have abnormal chest imaging and pulmonary function tests. Independent risk factors for long-COVID fatigue and dyspnea included female gender, obesity, and closer proximity to COVID-19 diagnosis; older age was not an independent predictor.

CONCLUSION

Older individuals with long-COVID have different persisting symptoms, with more pronounced pulmonary impairment. Women and individuals with obesity are at risk. Further research is warranted to investigate the natural history of long-COVID among the elderly population and to assess possible interventions aimed at promoting rehabilitation and well-being.

Risk factors and multidimensional assessment of long COVID fatigue: a nested case-control study

BACKGROUND

Fatigue is the most prevalent and debilitating long COVID symptom, however risk factors and pathophysiology of this condition remain unknown.We assessed risk factors for long COVID fatigue and explored its possible pathophysiology.

METHODS

Nested case-control study in a COVID recovery clinic. Individuals with (cases) and without (controls) significant fatigue were included. We performed a multidimensional assessment evaluating various parameters, including pulmonary function tests and cardiopulmonary exercise testing, and implemented multivariable logistic regression to assess risk factors for significant long COVID fatigue.

RESULTS

Total of 141 individuals were included. Mean age was 47 (SD 13) years; 115 (82%) were recovering from mild COVID-19. Mean time for evaluation was 8 months following COVID-19. Sixty-six (47%) individuals were classified with significant long COVID fatigue. They had significantly higher number of children, lower proportion of hypothyroidism, higher proportion of sore throat during acute illness and long COVID symptoms, and of physical limitation in daily activities.Individuals with fatigue had poorer sleep quality and higher degree of depression. They had significantly lower heart rate [153.52 (22.64) vs 163.52 (18.53), p=0.038] and oxygen consumption per Kg [27.69 (7.52) vs 30.71 (7.52), p=0.036] at peak exercise.The two independent risk factors for fatigue identified in multivariable analysis were peak exercise heart rate (odds ratio [OR] 0.79 per 10 beats/minute, 95% confidence interval [CI] 0.65-0.96, p=0.019); and long COVID memory impairment (OR 3.76, 95% CI 1.57-9.01, p=0.003).

CONCLUSIONS

Long COVID fatigue may be related to autonomic dysfunction, impaired cognition and decreased mood. This may suggest a limbic-vagal pathophysiology. Clinical Trial registration: NCT04851561.

ESCMID rapid guidelines for assessment and management of long COVID

Scope

The aim of these guidelines is to provide evidence-based recommendations for the assessment and management of individuals with persistent symptoms after acute COVID-19 infection and to provide a definition for this entity, termed ‘long COVID’.

Methods

We performed a search of the literature on studies addressing epidemiology, symptoms, assessment, and treatment of long COVID. The recommendations were grouped by these headings and by organ systems for assessment and treatment. An expert opinion definition of long COVID is provided. Symptoms were reviewed by a search of the available literature. For assessment recommendations, we aimed to perform a diagnostic meta-analysis, but no studies provided relevant results. For treatment recommendations we performed a systematic review of the literature in accordance with the PRISMA statement. We aimed to evaluate patient-related outcomes, including quality of life, return to baseline physical activity, and return to work. Quality assessment of studies included in the systematic review is provided according to study design.

Recommendations

Evidence was insufficient to provide any recommendation other than conditional guidance. The panel recommends considering routine blood tests, chest imaging, and pulmonary functions tests for patients with persistent respiratory symptoms at 3 months. Other tests should be performed mainly to exclude other conditions according to symptoms. For management, no evidence-based recommendations could be provided. Physical and respiratory rehabilitation should be considered. On the basis of limited evidence, the panel suggests designing high-quality prospective clinical studies/trials, including a control group, to further evaluate the assessment and management of individuals with persistent symptoms of COVID-19.

Challenges and Management of Long COVID in Individuals with Hematological Illnesses

COVID-19 has impacted hundreds of millions of people globally, a relatively large proportion of whom continue to suffer from ongoing, sometime debilitating symptoms. This phenomenon, termed “long COVID,” is difficult to diagnose and manage because of a paucity of objective findings and despite the abundance of descriptive data published so far. In this review, we aimed to describe the common manifestations of long COVID, diagnostic and management challenges, and address specific aspects in hematologic patients.

OUP accepted manuscript

Data regarding immunogenicity of mRNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines among kidney transplant recipients in the months following vaccination are lacking. We aimed to investigate humoral immune response at 3–4 months post-vaccination among a cohort of kidney transplant recipients, compared with a control group of dialysis patients. Anti-spike antibodies were tested at 1 and 3–4 months after vaccination. Of 259 kidney transplant recipients tested at a median time of 110 days from second vaccine dose, 99 (38%) were seropositive, compared with 83% (101/122) of control patients. Younger age, better renal function and lower immunosuppression levels were associated with seropositivity. A total of 14% (13/94) of participants seropositive at 1 month became seronegative at follow-up and 11% (18/165) became seropositive. The latter were mainly individuals with higher antibody levels at 1 month. Antibody levels at 3–4 months were significantly reduced in both study groups, although the decline was more pronounced in the control group. Kidney transplant recipients present poor antibody response to mRNA SARS-CoV-2 vaccination, with only 38% seropositive at 3–4 months. Nevertheless, the decay in antibody response over time is modest, and some patients may present delayed response, reaching adequate antibody levels at 3–4 months. Low seropositivity rates in this group call for investigating other immunization strategies.

Cardio-COVID clinic – a one-center experience

Background

Persistent symptoms affect a relatively large portion of coronavirus disease (COVID) survivors. Hence, specific clinics had been established in order to better characterize and manage this emerging entity of Post-COVID, among them our Cardio-COVID Clinic, which is dedicated to the cardiovascular (CV) aspects of the phenomenon.

Aim

To present the experience of our Cardio-COVID Clinic.

Methods

Included in this report are 76 adult patients seen at the clinic between June 2020 and March 2021, who have recovered from a polymerase chain reaction (PCR)-confirmed COVID, and who were suspected by their referring physicians to experience ongoing cardiac sequelae. All participants underwent a structured assessment by a single cardiologist, which consisted of history taking, physical examination (PE), electrocardiogram (ECG), trans-thoracic echocardiogram (TTE), and further tests as deemed appropriate, including any combination of Holter, ischemic provocation test, cardiopulmonary exercise test (CPET), cardiac magnetic resonance (CMR), and cardiac computed tomography (CCT).

Results

Initial visits occurred within a median of 131 days after diagnosis. Most participants (83%) were referred from our general Long-COVID Clinic. About half were males, and the mean age was 53 years. 18% of participants had prior CV conditions, and the majority (72%) had at least one CV risk factor, mostly dyslipidemia. Nearly all participants experienced a symptomatic acute illness, which was graded according to the National Institutes of Health (NIH) criteria as severe in 23% of the study cohort. As for Post-COVID, late symptoms were present in 97% of patients, the most common being dyspnea (57%). While PE was unremarkable in all but 3 patients who exhibited murmurs, ECG findings were revealed in 45% – mostly non-specific ST-T changes (31%) and conduction abnormalities (14%) – and TTE aberrations were discovered in 28% – including pericardial effusion (24%), reduced left ventricular ejection fraction (LVEF) (5%), grade 2 diastolic dysfunction (3%), moderate and up valvular dysfunction (1%), and systolic pulmonary hypertension (1%); right ventricular function was universally normal. Upon conclusion of the work-up, CV diagnoses were made in 8 (11%) patients – including myocarditis (4), myopericarditis (1), inappropriate sinus tachycardia (1), chronotropic incompetence (1), and an aberrant coronary (1). Of note, CPET and CMR had the highest diagnostic yield, in light of 57% positive results on each – followed by CCT, Holter, and provocation test. Interesting as well, among those with abnormal CMR findings, 40% had normal ECG's and TTE's. Also, none of the CV restraints on CPET translated to provocation test anomalies.

Conclusion

CV symptoms of Post-COVID are highly prevalent, but signify actual CV disease only in a minority of patients. Further research is needed that will help identify predictors for CV morbidity and define optimal clinical pathways.

Funding Acknowledgement

Type of funding sources: None.

Endocrinopathy-induced euvolemic hyponatremia

Euvolemic hyponatremia results from either the syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, or adrenal insufficiency. Furthermore, the criteria for diagnosis of SIADH entail the exclusion of hypothyroidism and hypoadrenalism. We aim to assess the yield of euvolemic hyponatremia workup focusing on underlying endocrinopathies in a real-world setting. A single-center retrospective study includes all patients diagnosed with euvolemic hyponatremia in a tertiary hospital between 1.1.2007 and 1.1.2013. Demographic, clinical, and laboratory data were collected from medical charts. Euvolemic hyponatremia was detected in 564 patients. Thyroid function was tested in 69% (391/564) and adrenal function was assessed in 29% (164/564) of cases. Endocrinopathy-induced euvolemic hyponatremia was diagnosed in nine (1.6%) patients: three patients were diagnosed with hypothyroidism-induced hyponatremia, three with adrenal insufficiency as an underlying cause, and three with central hypothyroidism and central hypoadrenalism. All nine had medical history and symptoms suggestive of endocrine deficiencies other than the hyponatremia, which resolved within 1-3 days after administration of hormone replacement therapy. Yield of performed workup for hypothyroidism and hypoadrenalism in euvolemic hyponatremia was low. However, in this real-world study, only a limited number of patients underwent a full ascertainment of hypoadrenalism and hypothyroidism, which was diagnosed only in patients with additional findings supportive of these endocrinopathies; a higher rate of undiagnosed endocrinopathies cannot be ruled out. As both hypoadrenalism and hypothyroidism are easily treatable, potentially life-threatening conditions, there are insufficient data to change current recommendation for their universal evaluation in patients with euvolemic hyponatremia.

Comparison of reporting phase III randomized controlled trials of antibiotic treatment for common bacterial infections in ClinicalTrials.gov and matched publications

OBJECTIVES

Discrepancies between ClinicalTrials.gov entries and matching publications were previously described in general medicine. We aimed to evaluate the consistency of reporting in trials addressing systemic antibiotic therapy.

METHODS

We searched ClinicalTrials.gov for completed phase III trials comparing antibiotic regimens until May 2017. Matched publications were identified in PubMed. Two independent reviewers extracted data and identified inconsistencies. Reporting was assessed among studies started before and after 1 July 2005, when the International Committee of Medical Journal Editors (ICMJE) required mandatory registration as a prerequisite for considering a trial for publication.

RESULTS

Matching publications were identified for 75 (70%) of 107 ClinicalTrials.gov entries. Median time from study completion to publication was 26 months (interquartile range 19-42). Primary outcome definition was inconsistent between ClinicalTrials.gov and publications in seven trials (7/72, 10%) and reporting of the primary outcome timeframe was inconsistent in 14 (14/71, 20%). Secondary outcomes definitions were inconsistent in 36 trials (36/66, 55%). Reporting of inclusion criteria and study timeline were inconsistent in 17% (13/65) and 3% (2/65), respectively. Trials started after July 2005 were significantly less likely to have reporting inconsistencies and were published in higher impact factor journals.

CONCLUSIONS

We found a lower inconsistency rate of outcome reporting compared with other medical disciplines. Reporting completeness and consistency were significantly better after July 2005. The ICMJE requirement for mandatory registration was associated with significant improvement in reporting quality in infectious diseases trials. Prolonged time lag to publication and missing data from unpublished trials should raise a discussion on current reporting and publishing procedures.

Chills During Hemodialysis: Prediction and Prevalence of Bacterial Infections - A Retrospective Cohort Study

INTRODUCTION

Chills are a complication of patients undergoing hemodialysis. The rate of infection among hemodialysis patients presenting with chills is not well established, and empirical broad-spectrum antibiotics are usually the rule.

METHODS

We performed a retrospective study aiming to assess the rates of infection and bacteremia in hemodialysis patients presenting with chills. We evaluated risk factors for infection and bacteremia and tested a prediction model for infection.

RESULTS

Overall, 269 hemodialysis patients with a first episode of chills were included. Ninety patients (33.5%) had bacteremia and 162 (60.2%) had an infection. Risk factors for bacteremia in multivariate analysis included fever (odds ratio [OR] 1.6; 95% confidence interval [CI], 1.1-2.3; P = .009) and vascular catheter as dialysis access (OR 6.2; 95% CI, 3.2-12.0, P <.001). Leukocytosis was an additional risk factor in multivariate analysis for any type of infection (OR 1.265; 95% CI, 1.113-1.438; P <.001). Using a prediction model to evaluate patients without obvious source of infection, we found that patients with fistula or graft as their access, without fever, abnormal leukocytes, or hypoalbuminemia, had a low rate (1/17, 6%) of bacteremia.

CONCLUSIONS

Hemodialysis patients presenting with chills during dialysis, with or without fever, have high rates (∼60%) of infection. Patients with no obvious source of infection, with fistula or graft as access, presenting without fever, leukocytosis, or hypoalbuminemia have low risk for bacteremia and may be investigated without prompt antibiotic treatment. All other patients should receive antibiotic coverage immediately following a chills episode.

Dose-dependent role of the cohesin complex in normal and malignant hematopoiesis

Cohesin complex members have recently been identified as putative tumor suppressors in hematologic and epithelial malignancies. The cohesin complex guides chromosome segregation; however, cohesin mutant leukemias do not show genomic instability. We hypothesized that reduced cohesin function alters chromatin structure and disrupts cis-regulatory architecture of hematopoietic progenitors. We investigated the consequences of Smc3 deletion in normal and malignant hematopoiesis. Biallelic Smc3 loss induced bone marrow aplasia with premature sister chromatid separation and revealed an absolute requirement for cohesin in hematopoietic stem cell (HSC) function. In contrast, Smc3 haploinsufficiency increased self-renewal in vitro and in vivo, including competitive transplantation. Smc3 haploinsufficiency reduced coordinated transcriptional output, including reduced expression of transcription factors and other genes associated with lineage commitment. Smc3 haploinsufficiency cooperated with Flt3-ITD to induce acute leukemia in vivo, with potentiated Stat5 signaling and altered nucleolar topology. These data establish a dose dependency for cohesin in regulating chromatin structure and HSC function.

Volumetric sub-surface imaging using spectrally encoded endoscopy

Endoscopic imaging below tissue surfaces and through turbid media may provide improved diagnostic capabilities and visibility in surgical settings. Spectrally encoded endoscopy (SEE) is a recently developed method that utilizes a single optical fiber, miniature optics and a diffractive grating for high-speed imaging through small diameter, flexible endoscopic probes. SEE has also been shown to provide three-dimensional topological imaging capabilities. In this paper, we have configured SEE to additionally image beneath tissue surfaces, by increasing the system's sensitivity and acquiring the complex spectral density for each spectrally resolved point on the sample. In order to demonstrate the capability of SEE to obtain subsurface information, we have utilized the system to image a resolution target through intralipid solution, and conduct volumetric imaging of a mouse embryo and excised human middle-ear ossicles. Our results demonstrate that real-time subsurface imaging is possible with this miniature endoscopy technique.

Large area confocal microscopy

Imaging large tissue areas with microscopic resolution in vivo may offer an alternative to random excisional biopsy. We present an approach for performing confocal imaging of large tissue surface areas using spectrally encoded confocal microscopy (SECM). We demonstrate a single-optical-fiber SECM apparatus, designed for imaging luminal organs, that is capable of imaging with a transverse resolution of 2.1 microm over a subsurface area of 16 cm2 in less than 1 min. Due to the unique probe configuration and scanning geometry, the speed and resolution of this new imaging technology are sufficient for comprehensively imaging large tissues areas at a microscopic scale in times that are appropriate for clinical use.

Three-dimensional imaging using spectral encoding heterodyne interferometry

We present a novel heterodyne approach for performing fast, three-dimensional spectrally encoded imaging. Volumetric data of a volunteer's finger and of coin surfaces were acquired at a rate of 5 volume sets per second with a depth resolution of 145 microm.

Double-clad fiber for endoscopy

Endoscopes employing a single optical fiber may have advantages over conventional fiber-bundle or CCD array imaging techniques, including the potential for greater flexibility and miniaturization. Although single-mode fibers can provide superior resolution compared with multimode fibers, they are prone to increased speckle noise and suffer from limited optical throughput and reduced depth of field. We demonstrate the use of a double-clad fiber for single-mode illumination and multimode detection to achieve high-resolution, reduced-speckle imaging with high optical throughput and a large depth of field.

Three-dimensional spectrally encoded imaging

A method for three-dimensional surface measurements with phase-sensitive spectrally encoded imaging is demonstrated. Both transverse and depth information is transmitted through a single-mode optical fiber, allowing this scheme to be incorporated into a miniature probe. This approach is demonstrated by measurement of the profile of a lens surface and by three-dimensional imaging of the face of a small doll.

Laser scanning third-harmonic-generation microscopy in biology

A laser scanning microscope using third-harmonic generation as a probe is shown to produce high-resolution images of transparent biological specimens. Third harmonic light is generated by a tightly focused short-pulse laser beam and collected point-by-point to form a digital image. Demonstrations with two biological samples are presented. Live neurons in a cell culture are imaged with clear and detailed images, including organelles at the threshold of optical resolution. Internal organelles of yeast cells are also imaged, demonstrating the ability of the technique for cellular and intracellular imaging.

Adaptive femtosecond pulse compression

A practical adaptive method for femtosecond optical pulse compression is demonstrated experimentally for the first time to our knowledge. The method is robust and capable of handling the general case of pulse compression, in which the input pulses are completely uncharacterized or partially characterized.