Pharyngeal-Cervical-Brachial Variant of Guillain-Barré Syndrome in a Patient of COVID-19 Infection

Guillain-Barré syndrome (GBS) has an annual incidence rate ranging from 0.4 to 1.7 cases per 1,00,000 population. Pharyngeal-cervical-brachial (PCB) variant is an extremely rare variant of GBS (3%), which presents with muscle weakness initially involving the neck, oropharynx, and upper extremities.

GBS often has an infectious inciting event leading to an autoimmune response. There has been an increase in the incidence of GBS during the COVID-19 pandemic, and several case studies have shown an association between the development of GBS and COVID-19 infection. High clinical suspicion is needed to reach a diagnosis. As PCB variant of GBS can have fatal outcomes, a good clinical knowledge of its presentation can allow timely life-saving interventions.

Here, we report a case of GBS with acute onset of neck and respiratory muscle weakness that progressed to upper limb weakness. The patient developed these symptoms two weeks after the onset of cough, fever, and malaise. PCB variant of GBS should always be considered as an important differential diagnosis in any patient presenting with limb weakness and bulbar palsy.

Human long-term bone marrow culture

Major advances in our understanding of human hematopoiesis have come from the development of semisolid in vitro culture techniques for the detection of progenitor cells capable of colony formation (see Chapter 28 , this volume). However, colony assays select for hematopoietic precursors committed to a specific lineage(s) and, therefore, are of limited value in the assessment of very early progenitor cells. Also, they do not provide a means of assessing the influence of microenvironmental cells deemed essential for maintaining hematopoiesis in vivo (1). Furthermore, for the assays to be valid, cells must be plated at a sufficiently low concentration to ensure clonality (a condition in which each colony has arisen from a single progenitor cell). Consequently, cell-cell interactions that may be important in exerting regulatory effects on hematopoiesis are likely to be minimal.

In vitro clonal culture of human hematopoietic progenitor cells

Human hematopoietic tissue represents a complex developmental system that is closely regulated to ensure the maintenance of appropriate levels of circulating blood cells. At least nine distinct lineages of cells at various stages of maturation have been described (1). Substantial progress in the study of hematopoietic stem cell ontogeny has resulted from the development of semisolid culture methods for the detection of committed progenitor cells. The assays define specific individual precursor cells indirectly by the ability of these cells to form colonies consisting of clonally expanded progeny at varying stages of differentiation. In turn, these methods have led to the identification, characterization, and synthesis by recombinant DNA techniques of some of the growth factors capable of stimulating colony formation and infer to an in vivo regulatory role for such factors in hematopoiesis.

Ketoconazole: a possible direct cytotoxic effect on prostate carcinoma cells

Ketoconazole has been recently used in the treatment of advanced prostatic cancer and is believed to exert its effect by inhibition of androgen production. In order to determine whether ketoconazole exerts an additional direct cytotoxic effect on prostate cancer cells, we studied its effect on human hormone-independent prostate cancer cell lines (PC-3 and DU-145) in an in vitro clonogenic tumor assay. We showed that clinically achievable doses of ketoconazole caused greater than 90% suppression of tumor colony growth.

Immunoreactive parathyroid hormone and in vitro inhibition of erythropoiesis by uremic serum in patients on continuous ambulatory peritoneal dialysis

Inhibition of erythropoiesis in vitro by uremic serum is well established. The role of parathyroid hormone (PTH) as inhibitor of erythropoiesis is uncertain. To further elucidate this effect we correlated the in vitro growth of red cell progenitors (BFU-E) in the presence of uremic serum from 26 patients on continuous ambulatory peritoneal dialysis with levels of immunoreactive PTH in the serum. The patients had a mean hemoglobin level of 100 +/- 20.1 g/l. The BFU-E growth was 98.8 +/- 28.3% of control. No correlation between BFU-E growth and hemoglobin was found. A significant negative correlation between levels of immunoreactive PTH and BFU-E growth was found (p = 0.05). These results support the notion that PTH or PTH fragment(s) might be responsible for the in vitro inhibition of erythropoiesis by uremic serum in patients on continuous ambulatory peritoneal dialysis.